Person: Blas Corral, María Ángeles de
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Blas Corral
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María Ángeles de
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Proyectos e Ingeniería Rural
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0000-0001-7860-921X
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1931
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Publication Open Access Proposal and evaluation of typical illuminance year (TIY) generation procedures from illuminance or irradiance data for daylight assessment in the long term(Elsevier, 2020) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Torres Escribano, José Luis; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaWhen assessing the long-term daylight availability or the performance of natural lighting systems in a given location, it is necessary to have representative data of local daylight conditions. The use of a daylight test reference year (TRY) becomes a good option in these cases. This paper proposes and evaluates a procedure for the generation of a typical illuminance year (TIY) considering illuminance as the only variable for selecting the typical periods that make up the reference year. Two versions of TIY are presented, one composed of 12 typical months selected from the series of observations and another composed of 365 typical days. Each of these versions is used to obtain a global illuminance TIY (TGIY) and a diffuse illuminance TIY (TDIY) from a 27-year dataset corresponding to the Vaulx-en-Velin station (France). Furthermore, 12 luminous efficacy models have been evaluated in order to obtain a TIY from a TRY generated from irradiance data when no illuminance data are available. Thus, a global luminous efficacy model and a diffuse model are selected after benchmarking different models, considering both their original coefficients and those adjusted to local conditions. The results reveal that the monthly version of the TGIY and the daily version of the TDIY show the best overall fit to the long-term dataset. TIYs obtained from illuminance data are also observed to be statistically indistinguishable from those obtained after applying a luminous efficacy model to an irradiance-based TRY.Publication Open Access Evaluation of two procedures for selecting the CIE standard sky type using high dynamic range images(International Solar Energy Society, 2019) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Torres Escribano, José Luis; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Ormazábal Pagola, Mikel; Ingeniería; Ingeniaritza; Ciencias; Zientziak; Gobierno de Navarra / Nafarroako GobernuaThe characterization of sky conditions according to the CIE Standard General Sky classification requires knowledge of diffuse luminance angular distribution in the sky vault. This variable is usually measured by sky scanners. However, commercial sky scanners have different drawbacks related to their resolution and measurement time. An alternative to these devices is the use of sky images captured with a digital camera equipped with a fisheye lens. The range of luminances that may occur in the sky makes it necessary to use high dynamic range (HDR) images obtained by the fusion of a series of low dynamic range (LDR) images. Two procedures for the characterization of sky conditions according to the CIE standard using HDR images have been applied and evaluated.Publication Open Access Evaluación de la aplicabilidad del año de referencia UNE-EN ISO 15927 ainstalaciones fotovoltaicas(Fundación General de la Universidad Politécnica de Madrid, 2014) Torres Escribano, José Luis; Blas Corral, María Ángeles de; García Gorostiaga, Almudena; García Ruiz, Ignacio; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta ProiektuakEl desarrollo y expansión de las tecnologías de aprovechamiento de la energía solar hace necesario disponer de datos meteorológicos representativos de un determinado lugar que permitan predecir el comportamiento energético de estos sistemas a largo plazo. Existen numerosos procedimientos para la composición de Años Meteorológicos Típicos (TMYs). No obstante, el único método normalizado para la construcción de años de referencia es el descrito en la norma UNE-EN ISO 15927-4. Este método está orientado a la construcción de años sintéticos para la estimación de cargas térmicas en la edificación. En este trabajo se evalúa la aplicabilidad del método UNE-EN ISO a instalaciones fotovoltaicas, comprobándose la bondad de los años de referencia obtenidos en la estimación de la energía eléctrica anual producida por un sistema fotovoltaico.Publication Open Access Evaluación comparativa de 19 modelos de estimación de irradiancia difusa sobre planos inclinados dependiendo del tipo de cielo estándar ISO/CIE(LNEG, 2020) García Ruiz, Ignacio; Torres Escribano, José Luis; Blas Corral, María Ángeles de; Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; Illanes, R.; Ingeniería; Ingeniaritza; Ciencias; ZientziakEn este trabajo se han evaluado 19 modelos de estimación de irradiancia difusa sobre el plano inclinado, que incluyen tanto modelos isotrópicos o pseudoisotrópicos como modelos anisotrópicos. Dicha evaluación se ha llevado a cabo a partir una serie de 5396 observaciones de irradiancia global, difusa y directa realizadas entre julio y diciembre de 2018 en la estación radiométrica de la Universidad Pública de Navarra (UPNA). El estado del cielo correspondiente a cada observación se ha caracterizado de acuerdo con el CIE Standard General Sky propuesto en la norma ISO 15469:2004(E)/CIE S 011/E:2003. Para esta clasificación se han utilizado las medidas de distribución angular de luminancia y radiancia proporcionadas por un escáner de cielo ubicado en la propia estación de la UPNA. De tal manera que, para cada combinación de orientación e inclinación del plano, se ha evaluado la bondad de los distintos modelos de acuerdo con los 15 tipos de cielo estándar propuestos por la norma ISO/CIE. Los resultados revelan que el modelo de Perez et al. 2 presenta los mejores resultados globales, así como en 5 de los 15 tipos de cielo ISO/CIE.Publication Open Access Diffuse irradiance on tilted planes in urban environments: evaluation of models modified with sky and circumsolar view factors(Elsevier, 2021) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Hernández Salueña, Begoña; Sáenz Gamasa, Carlos; Torres Escribano, José Luis; Ingeniaritza; Zientziak; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; CienciasNumerous studies have analyzed existing irradiance models for estimating sky diffuse irradiance on tilted planes. However, few have evaluated the suitability of these models for estimating irradiance in obstructed environments, specifically considering the effects of obstacles. In this study, three irradiance models —one of them with five variants— for estimating diffuse irradiance on tilted planes located in urban environments were evaluated. All models have been adapted to consider the effect of an urban canyon on the diffuse irradiance received on a tilted plane through the sky view factor and the circumsolar view factor. All the models were evaluated against the diffuse irradiance values obtained by the ISO 15469:2004(E)/CIE S 011/E:2003 angular distribution model. Therefore, it was necessary to determine the standard sky type corresponding to each record of the measurements performed by a sky scanner at the radiometric station of UPNA (Spain). A total of 4,864 scenarios were considered to occur from the combination of different orientations and inclinations of the plane, and different orientations and aspect ratios of the urban canyon. The results revealed that the Perez model considering a 35° half-angle circumsolar region has the best performance, followed by the Perez model considering a 45° half-angle circumsolar region.Publication Open Access Validation and calibration of models to estimate photosynthetically active radiation considering different time scales and sky conditions(Elsevier, 2022) Blas Corral, María Ángeles de; García-Rodríguez, Ana; García Ruiz, Ignacio; Torres Escribano, José Luis; Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaPhotosynthetically Active Radiation (PAR) is a fundamental parameter for developing plant productivity models. Nevertheless, instrumentation for measuring PAR and to record it is scarce at conventional meteorological stations. Several procedures have therefore been proposed for PAR estimation. In this work, 21 previously published analytical models that correlate PAR with easily available meteorological parameters are collected. Although longer time scales were considered in the original publications, a minute range was applied in this work to calibrate the PAR models. In total, more than 10 million input records were gathered from the SURFRAD station network from a 10-year long time series with data frequencies recorded every 1 min. The models were calibrated both globally, using data from all stations and locally, with data from each station. After calibration, the models were validated for minute, hourly and daily data, obtaining low fitting errors at the different stations in all cases, both when using the globally calibrated models and with the models calibrated for each location. Although the PAR results in general improved for locally calibrated models, the use of local models is not justified, since the global models presented offered very satisfactory PAR results for the different climatic conditions where the meteorological stations are located. Thus, PAR estimation model should then be selected, solely considering the meteorological variables available at the specific location. When applying the globally calibrated models to input data classified according to sky conditions (from clear to overcast), the PAR models continued to perform satisfactorily, although the error statistics of some models for overcast skies worsened.Publication Open Access The sky characterization according to the CIE Standard General Sky: comparative analysis of three classification methods(Elsevier, 2020) García Ruiz, Ignacio; Blas Corral, María Ángeles de; Torres Escribano, José Luis; Ingeniaritza; Institute of Smart Cities - ISC; IngenieríaSince the publication of the standard sky luminance distributions (SSLD) that was consolidated in the ISO 15469:2004(E)/CIE S 011/E:2003, numerous procedures have emerged for the characterization of the sky condition according to that standard. Precisely, the use of different procedures for the classification of the skies of a certain place according to the ISO/CIE standard can lead to obtain different frequencies of sky types. The existing uncertainties in the characterization of the sky condition according to the CIE Standard General Sky as a consequence of the classification procedure used are analyzed in this study. For this, three different classification procedures are used to characterize the sky radiance and luminance distribution measurements made by means of a sky-scanner in Pamplona (Spain) from 2007 to 2013. That is, (1) a method focused on determining the relative gradation and indicatrix functions, (2) a method based on the comparison of measured and standard luminances normalized against the horizontal diffuse illuminance, and (3) a new high-spatial-resolution approach that compares measured and standard luminances relative to zenith. In general terms, it is concluded that there is some uncertainty in the classification depending on the procedure used to characterize the sky.