Browsing by Author "Castillejo Cuberos, Armando"

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    Analyzing regional and local changes in irradiance during the 2019 total solar eclipse in Chile, using field observations and analytical modeling
    (MDPI, 2021) Castillejo Cuberos, Armando; Cardemil Iglesias, José Miguel; Escobar Moragas, Rodrigo
    Solar eclipses are astronomic phenomena in which the Earth’s moon transits between the planet and the Sun, projecting a shadow onto the planet’s surface. As solar power installed capacity increases, detailed studies of this region-wide phenomenon’s effect in irradiance is of interest; how-ever, the literature mainly reports its effects on localized scales. A measurement campaign spanning over 1400 km was pursued for the 2 July 2019 total solar eclipse in Chile, to register the event and establish a modeling framework to assess solar eclipse effects in irradiance over wide regional scales. This work describes the event and presents an estimation framework to decompose atmospheric and eclipse effects on irradiance. An analytical model was applied to study irradiance attenuation throughout the Chilean mainland territory, using satellite-derived and astronomical data as inputs compared to ground measurements in eight stations. Results showed good agreement between model and observations, with Mean Bias Errors of −0.008 to 0.98 W/m2 for Global Horizontal Irradiance and −0.004 to −4.664 W/m2 for Direct Normal Irradiance, with Normalized Root Mean Squared Errors of 0.7–5.8% and 1.4–12.2%, respectively. Energy losses due to obscuration corre-sponded between 20–40% for Global Horizontal Irradiance and 25–50% for Direct Normal Irradi-ance over Chilean territory.
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    Detection and characterization of cloud enhancement events for solar irradiance using a model-independent, statistically-driven approach
    (2020) Castillejo Cuberos, Armando; Escobar Moragas, Rodrigo
    Cloud enhancement events are instances in which the cloud pattern increases global horizontal irradiance on the ground above levels higher than would otherwise be expected during clear sky with cloudless conditions, and in general, these events are characterized by high irradiances occurring during highly changing transient conditions. Even though it is a well-known although infrequent phenomenon, currently no consensus exists as to its formal definition. However, several studies point out to a need for a better understanding of this phenomenon due to their effects on mathematical models or photovoltaic systems behavior during these instances, as results show significant deviations with respect to the expected results in normal conditions. Due to these issues, the present work intends to explore cloud enhancement definitions and detection methods, for which a novel model-independent, statistically-driven approach is proposed and compared to three other models found in the literature. Assessments are made regarding the main aspects of the phenomenon: frequency of occurrence, clearness index, diffuse fraction and its relationship with solar resource variability. Data from eight measurements sites throughout Chile, with different climatic characteristics is used. To further support the analysis made, monthly maximum expected clear sky irradiance for each site was estimated through satellite-based data as well as with estimation from ground measurements. Finally, the highest irradiances are presented for each measurement site reporting, the record irradiances for one-minute data thermopile and photodiode pyranometers.
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    Diffuse fraction estimation using the BRL model and relationship of predictors under Chilean, Costa Rican and Australian climatic conditions
    (2019) García Rojas, Redlich Javier; Alvarado, Natalia; Boland, John W.; Escobar Moragas, Rodrigo; Castillejo Cuberos, Armando
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    High-performance subambient radiative cooling enabled by optically selective and thermally insulating polyethylene aerogel
    (2019) Leroy, A.; Bhatia, B.; Kelsall, C. C.; Castillejo Cuberos, Armando; Di Capua Hidalgo, Mario Antonio; Zhao, L.; Zhang, L.; Guzmán Cuevas, Amador Miguel; Wang, E.N.
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    Irradiance separation model parameter estimation from historical cloud cover statistical properties
    (2024) Castillejo Cuberos, Armando; Cardemil Iglesias, José Miguel; Boland, J.; Escobar Moragas, Rodrigo Alfonso
    Irradiance separation models allow the decomposition of Global Horizontal Irradiance into Diffuse Horizontal and Direct Normal Irradiances. These models need fitting to the irradiance characteristics of the location of interest using locally measured ground data. For locations that only measure Global Horizontal Irradiance, current state of the art establishes the use of parameters obtained for another location that measures the three components, with similar climate characteristics. Nevertheless, this results in a lack of localized character for estimates and requires fitting model parameters for all possible climates, which can be infeasible given data availability. This work presents a novel approach based on the hypothesis that the separation model's parameters are a function of the statistical properties of satellite-derived cloud cover estimates. The proposed methodology was evaluated in 23 sites covering all main Koppen-Geiger climatic types and different cloud coverage properties using the Boland-Ridley-Lauret diffuse fraction model. The model performs similarly as locally adjusting the model, with Root Mean Square Errors of 0.087-0.15 diffuse fraction units versus 0.077-0.127 for locally optimized parameters, and offers adequate performance across climates and cloud characteristics. These results encourage future research by generalizing parameter estimation for other diffuse fraction models. The main applications for this research are the estimation of irradiance components where no local data is available for model fitting and the enhancement or complementarity of satellite estimates of surface irradiance. Furthermore, it allows the estimation of missing irradiance components due to equipment failure in locations with insufficient data for a representative, locally adapted model.
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    Power system optimization and sub-hourly simulation of solar photovoltaic plants with battery energy storage systems considering ancillary services
    (2024) Ibarra Alemany, Martín Felipe; Lorca Gálvez, Álvaro Hugo; Castillejo Cuberos, Armando; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    La integracióon de fuentes de energía renovable variable en la red eléctrica presenta desafíos y oportunidades significativos. Entre las soluciones más prometedoras se encuentra el despliegue de Sistemas de Almacenamiento de Energía con Baterías, que pueden ofrecer múltiples servicios. Su instalación se ha visto obstaculizada por desafíos regulatorios y altos costos, los cuales están disminuyendo año tras año. Este trabajo examina los marcos regulatorios, los incentivos del mercado y las métricas operativas y financieras necesarias para hacer que las plantas de energía solar fotovoltaica con BESS sean económicamente viables. Se propone un modelo operativo en dos etapas de una red eléctrica que considera reservas, la instalación de baterías y la expansión de plantas PV existentes, utilizando también como entrada la carga y el estado de las baterías basado en un modelo de simulación PV+BESS usando el software System Advisor Model, para incorporar las no linealidades de BESS. El modelo se prueba con la red eléctrica chilena, con 26 nodos para la etapa de instalación de BESS y 212 para la etapa de operación. Al abordar estos factores, la investigación busca proporcionar información sobre cómo las plantas PV+BESS pueden integrarse efectivamente en el mercado energético, apoyando en última instancia la adopción más amplia de tecnologías de energía renovable. Los resultados muestran que, bajo los marcos regulatorios y de remuneración considerados, la ubicación no afecta significativamente la viabilidad económica, las soluciones favorecidas por el ISO pueden no ser adecuadas para los operadores de plantas, la degradación varía significativamente entre plantas y escenarios, y hay factores importantes a considerar al diseñar plantas PV+BESS en tales mercados, como la probabilidad de activación de reservas.
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    Short‐term deterministic solar irradiance forecasting considering a heuristics‐based, operational approach
    (MDPI, 2021) Castillejo Cuberos, Armando; Boland, John; Escobar Moragas, Rodrigo
    Solar energy is an economic and clean power source subject to natural variability, while energy storage might attenuate it, ultimately, effective and operationally feasible forecasting techniques for energy management are needed for better grid integration. This work presents a novel deterministic forecast method considering: irradiance pattern classification, Markov chains, fuzzy logic and an operational approach. The method developed was applied in a rolling manner for six years to a target location with no prior data to assess performance and its changes as new local data becomes available. Clearness index, diffuse fraction and irradiance hourly forecasts are analyzed on a yearly basis but also for 20 day types, and compared against smart persistence. Results show the proposed method outperforms smart persistence by ~10% for clearness index and diffuse fraction on the base case, but there are significant differences across the 20 day types analyzed, reaching up to +60% for clear days. Forecast lead time has the greatest impact in forecasting performance, which is important for any practical implementation. Seasonality in data gaps or rejected data can have a definite effect in performance assessment. A novel, comprehensive and detailed analysis framework was shown to present a better assessment of forecasters’ performance.
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    State of the art and future prospects for solar PV development in Chile
    (2018) Zurita Villamizar, Adriana; Castillejo Cuberos, Armando; García, Maurianny; Mata Torres, Carlos Enrique; Simsek, Yeliz; García Rojas, Redlich Javier; Torres Antoñanzas, Fernando; Escobar Moragas, Rodrigo
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    Techno-economic assessment of photovoltaic plants considering high temporal resolution and non-linear dynamics of battery storage
    (Elsevier Ltd, 2023) Castillejo Cuberos, Armando; Cardemil, J.M.; Escobar, R.
    © 2023 Elsevier LtdThe addition of energy storage systems for photovoltaic plants in order to provide reliability and flexibility in their dispatch is a very active line of research, as it studies plant design configurations and different dispatch strategies to improve the coupling of variable renewable solar generation with conventional hydro/thermal electric grids to enable large-scale participation of renewables in these systems. Nevertheless, battery degradation is a critical parameter to assess the plant's lifetime performance as it depends upon the battery's operational principles, design and usage pattern, which coupled with their inherent non-linearities makes them a potential source of uncertainty in assessments, should the involved phenomena be overly simplified. In this work, we explore different photovoltaic plant configurations with batteries operating under a dispatch optimization algorithm that considers operational power forecasts, market pricing information and a series of constraints to improve their coupling with electric networks. The battery system is modelled considering the electrical, thermal and degradation phenomena occurring during its life cycle, as well as considering a variable charge/discharge efficiency and it's simulated at high temporal resolution to account for any sub-hourly non-linear dynamics. The results show that considering time steps over 30 min for battery simulation during dispatch can lead to noticeable differences in key performance indicators when compared to one-minute cases and it was found that 10-minutes offered the best compromise in accuracy and computational cost. Additionally, it was found that, depending on their design, effective yearly degradation rates for batteries are highly variable and can reach values that deviate substantially from commonly-used constant assumptions, demonstrating the value of degradation modeling for lifecycle assessment. Finally, it was observed that plant configurations suited for specific operational modes such as smoothing and peak shaving could be obtained by analyzing their dispatch characteristics under the dispatch optimization algorithm, instead of following the usual approach of setting the operational mode and tuning the plant for it. This finding suggests that a design philosophy that adapts the plant's design to the dynamic the market's dynamic could be highly suitable for electric systems in which no central agent determines the expansion of the system.
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    Temporal upscaling of solar radiation components using an analytical model for variability modeling
    (2024) Castillejo Cuberos, Armando; Cardemil Iglesias, José Miguel; Escobar Moragas, Rodrigo Alfonso
    To properly design systems that harness the solar resource, reliable measurements or estimates of its availability are needed. Often, this data is only available at temporal resolutions that are not sufficiently fine to capture the short-term fluctuations of the solar resource, creating uncertainty in the design and performance assessment of solar-powered systems. Synthetic irradiance generation techniques aim to create high temporal resolution estimates starting from lower resolution data, however, a literature review on the topic shows opportunities for improvement regarding the generality of the generation and evaluation approaches. This work proposes novel methods to estimate a quantifiable indicator of short-term variability from hourly data, a new temporal upscaling methodology for time series of arbitrary origin and destination temporal resolution, based on explicit mathematical functions and sufficient generality for application in different contexts, and an improved assessment methodology. The method was applied tor ground and satellite upscaling up to 1 min, resulting in time series with characteristics consistent with those of a higher temporal resolution and exhibit minimum deviations against the original time series characteristics. This method has applications not only for upscaling of low temporal resolution data, but also for gap-filling techniques and the upscaling of hourly solar radiation forecasts.
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    Towards flexible photovoltaic power, using energy storage and power forecasts : a thecno-economic assessment
    (2021) Castillejo Cuberos, Armando; Escobar Moragas, Rodrigo; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    El presente trabajo refiere al diseño y operación de centrales fotovoltaicas acopladas con sistemas de almacenamiento de energía en baterías, usando pronósticos de generación fotovoltaica e información del Mercado eléctrico para formular el despacho de la planta y proveer un nivel de cumplimiento técnico, analizando el efecto de la estructura de costos en la factibilidad económica de estos proyectos. El objetivo principal de este trabajo es desarrollar una metodología para el dimensionamiento apropiado de plantas fotovoltaicas acopladas a sistemas de almacenamiento de energía en baterías, considerando pronósticos de generación e información del mercado eléctrico. Para este efecto, cuatro objetivos específicos se definieron, relacionados con: un análisis detallado de las características del recurso solar, determinando el efecto de su variabilidad en los pronósticos de generación fotovoltaica; el desarrollo de un sistema de pronóstico de generación fotovoltaica y su aplicación para su despacho eléctrico considerando acople con un sistema de baterías, y la evaluación de su desempeño técnico y económico bajo distintos escenarios económicos. Esta tesis se compone de 6 capítulos, de los cuales 3 corresponden a artículos científicos en revistas indexadas. Metodológicamente, este estudio se divide en cuatro etapas. La primera (en los capítulos 2 y 3) se enfoca en las técnicas para la evaluación del recurso solar y su aplicación para la definición y análisis de sus características dinámicas en distintos contextos espaciotemporales, lo cual sirve como dato de entrada para la simulación de plantas y la formulación de los pronósticos (capítulo 4). La segunda etapa se enfoca en las técnicas de pronóstico de radiación solar y su estado del arte, con el propósito de desarrollar metodologías efectivas tanto para el pronóstico como la evaluación de su desempeño, caracterizándolo bajo distintas circunstancias y tomando en cuenta consideraciones operacionales relacionadas con la utilidad de los pronósticos como herramienta para la toma de decisiones. La tercera etapa refiere al modelado de la planta fotovoltaica y el sistema de baterías, la integración con el pronóstico meteorológico y el desarrollo del algoritmo de despacho, considerando tanto el pronóstico de generación como información del mercado eléctrico, restricciones operacionales y la compleja dinámica de las baterías en cuanto a los fenómenos eléctricos y térmicos y su relación con la degradación de las mismas. La etapa final (capítulo 5) se enfoca en la evaluación técnica de estas plantas, para determinar su cumplimiento con la planificación de despacho, pero también evaluando su costo nivelado de energía (LCOE). Esta evaluación se realiza considerando los precios actuales y proyectados para los componentes de la panta y, evalúa medidas adicionales para la reducción de los costos totales a lo largo del ciclo de vida de la planta, modificando ciertos parámetros de diseño. Los resultados de este trabajo demuestran que es necesario considerar las características dinámicas del recurso solar en su evaluación, ya que locaciones con niveles de energía similares pueden exhibir patrones dinámicos muy disímiles a través de distintas escalas temporales. Similarmente, las características del recurso solar tienen un efecto definitivo en el desempeño de los métodos de pronóstico y es necesario evaluarlos no solamente en los comúnmente reportados indicadores anuales o estacionales, sino para condiciones meteorológicas específicas, ya que los resultados pueden ser muy disímiles entre estos. La anticipación del pronóstico es una consideración operacional importante para la toma de decisiones, que tiene un efecto pronunciado en el desempeño de un método de pronóstico y por tanto es un parámetro clave a considerar en su evaluación. Para alcanzar un despacho confiable de plantas fotovoltaicas tanto en cantidad de energía como su tasa de cambio, es necesaria una combinación de sobredimensionamiento del campo solar y la adición de almacenamiento de energía (respectivamente). El sistema de baterías es el principal contribuyente (~60%) al costo total durante el ciclo de vida, con su degradación siendo un parámetro definitorio para la evaluación económica y por tanto requiere una evaluación cuidadosa, ya que depende mayormente del patrón de uso de las mismas. Así mismo, la selección del umbral de reemplazo de baterías tiene una influencia significativa en el costo durante el ciclo de vida, su valor apropiado es específico para el tamaño de planta y su selección cuidadosa tiene el potencial de disminuir el LCOE entre 10-20%. Finalmente, es posible lograr plantas con mayor a 90% de cumplimiento en planificación de despacho una vez que reducciones de costo substanciales en los componentes de la planta ocurran y técnicas apropiadas de dimensionamiento sean utilizadas, permitiendo alcanzar LCOEs menores a 70$/MWh para plantas con hasta 4 horas de almacenamiento de energía.
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    Understanding solar resource variability: An in-depth analysis, using Chile as a case of study
    (2020) Castillejo Cuberos, Armando; Escobar Moragas, Rodrigo