Capability curve analysis of photovoltaic generation systems

The present article assesses the study of the PV generator capability curves for use in large scale photovoltaic power plants (LS-PVPPs). For this purpose, the article focuses on three main aspects: (i) the modelling of the main components of the PV generator, (ii) the operational limits analysis of the PV array together with the inverter, and (iii) the capability curve analysis considering variable solar irradiance and temperature. To validate this study a PVPP of 1 MW is designed, modelled and simulated in DIgSILENT PowerFactory®. The results for each case scenario shows that the capability curve and the limitations are directly affected by: the solar irradiance, temperature, dc voltage, and the modulation index.Peer ReviewedPostprint (author's final draft

Topologies for large scale photovoltaic power plants

© 2016 Elsevier Ltd. All rights reserved. The concern of increasing renewable energy penetration into the grid together with the reduction of prices of photovoltaic solar panels during the last decade have enabled the development of large scale solar power plants connected to the medium and high voltage grid. Photovoltaic generation components, the internal layout and the ac collection grid are being investigated for ensuring the best design, operation and control of these power plants. This paper addresses the review of components as photovoltaic panels, converters and transformers utilized in large scale photovoltaic power plants. In addition, the distribution of these components along this type of power plant and the collection grid topologies are also presented and discussed.Peer ReviewedPostprint (author's final draft

Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS II. The complete high resolution extinction map and implications for Bulge studies

We use the Vista Variables in the Via Lactea (VVV) ESO public survey data to measure extinction values in the complete area of the Galactic bulge covered by the survey at high resolution. We derive reddening values using the method described in Paper I. This is based on measuring the mean (J-Ks) color of red clump giants in small subfields of 2' to 6' in the following bulge area: -10.3<b<+5.1 and -10<l<+10.4. To determine the reddening values E(J-Ks) for each region, we measure the RC color and compare it to the (J-Ks) color of RC stars measured in Baade's window, for which we adopt E(B-V)=0.55. This allows us to construct a reddening map sensitive to small scale variations minimizing the problems arising from differential extinction. The significant reddening variations are clearly observed on spatial scales as small as 2'. We find a good agreement between our extinction measurements and Schlegel maps in the outer bulge, but, as already stated in the literature the Schlegel maps are not reliable for regions within |b| < 6. In the inner regions we compare our results with maps derived from DENIS and Spitzer surveys. While we find good agreement with other studies in the corresponding overlapping regions, our extinction map has better quality due to both higher resolution and a more complete spatial coverage in the Bulge. We investigate the importance of differential reddening and demonstrate the need for high resolution extinction maps for detailed studies of Bulge stellar populations and structure. The extinction variations on scales of up to 2'-6', must be taken into account when analysing the stellar populations of the Bulge.Comment: Accepted for publication in A&

Performance Evaluation of Half-Cut PV Market Modules in Outdoor Conditions

Photo Voltaic (PV) technology continues to advance, seeking to optimize efficiency and performance. Half-cut and back contact PV modules have emerged as a promising innovation, aiming to enhance energy yield and durability. This study presents a comprehensive analysis of outdoor performance in normal operation considering four technologies of PV modules. The research focuses on evaluating the efficiency of these modules in real-world conditions. A dedicated outdoor test facility at SolarTechLAB exposed the modules to varying solar radiance and environmental factors. We measured the current-voltage (I-V) curves of each module, and we calculated the performance ratio using the lEC 61724-1 Standard. We determined that half- cut cells present a higher performance ratio than full-cell modules in a range between 3.7 to 7 %

Active and reactive power control of a PV generator for grid code compliance

As new grid codes have been created to permit the integration of large scale photovoltaic power plants into the transmission system, the enhancement of the local control of the photovoltaic (PV) generators is necessary. Thus, the objective of this paper is to present a local controller of active and reactive power to comply the new requirements asked by the transmission system operators despite the variation of ambient conditions without using extra devices. For this purpose, the control considers the instantaneous capability curves of the PV generator which vary due to the change of solar irradiance, temperature, dc voltage and modulation index. To validate the control, the PV generator is modeled in DIgSILENT PowerFactory® and tested under different ambient conditions. The results show that the control developed can modify the active and reactive power delivered to the desired value at different solar irradiance and temperature

Active and reactive power control of a PV generator for grid code compliance

As new grid codes have been created to permit the integration of large scale photovoltaic power plants into the transmission system, the enhancement of the local control of the photovoltaic (PV) generators is necessary. Thus, the objective of this paper is to present a local controller of active and reactive power to comply the new requirements asked by the transmission system operators despite the variation of ambient conditions without using extra devices. For this purpose, the control considers the instantaneous capability curves of the PV generator which vary due to the change of solar irradiance, temperature, dc voltage and modulation index. To validate the control, the PV generator is modeled in DIgSILENT PowerFactoryr and tested under different ambient conditions. The results show that the control developed can modify the active and reactive power delivered to the desired value at different solar irradiance and temperature.Postprint (published version

Energy Scheduling and Performance Evaluation of an e-Vehicle Charging Station

This paper proposes an energy management system (EMS) for a photovoltaic (PV) grid-connected charging station with a battery energy storage system (BESS). The main objective of this EMS is to manage the energy delivered to the electric vehicle (EV), considering the price and (Formula presented.) emissions due to the grid’s connection. Thus, we present a multi-objective two-stage optimization to reduce the impact of the charging station on the environment, as well as the costs. The first stage of the optimization provides an energy schedule, taking into account the PV forecast, the hourly grid’s (Formula presented.) emissions factor, the electricity price, and the initial state of charge of the BESS. The output from this first stage corresponds to the maximum power permitted to be delivered to the EV by the grid. Then, the second stage of the optimization is based on model predictive control that looks to manage the energy flow from the grid, the PV, and the BESS. The proposed EMS is validated using an actual PV/BESS charging station located at the University of Trieste, Italy. Then, this paper presents an analysis of the performance of the charging station under the new EMS considering three main aspects, economic, environmental, and energy, for one month of data. The results show that due to the proposed optimization, the new energy profile guarantees a reduction of 32% in emissions and 29% in energy costs

La participación política de colectivos estudiantiles en los centros de educación superior en el Ecuador : el caso de la Pontificia Universidad Católica del Ecuador

La participación política estudiantil en la Universidad Católica del Ecuador, en la sede Quito, se encuentra significativamente debilitada debido a dos tipos de factores, a saber: institucionales y sociales. La apatía política en los estudiantes caracteriza el ambiente político universitario del período de estudio 2011-2013. Si bien los factores institucionales son también sociales, esta distinción tiene una razón de tipo metodológica, para una mejor comprensión del problema de la apatía estudiantil. Los factores institucionales se refieren al conjunto de normas universitarias (estatutos y reglamentos) y prácticas del cuerpo administrativo universitario, que configuran las condiciones para amoldar la participación política y encapsularla en el derecho al voto. Como resultado, se producen y reproducen valores y percepciones de la participación política estudiantil en autoridades y estudiantes que minan su terreno y que delimita el poder de decisión efectivo de los estudiantes en las instancias de cogobierno. Los factores sociales se refieren al habitus de los estudiantes y de las autoridades, aquellos esquemas de percepción, pensamiento y acción, tanto de estudiantes como de autoridades, que reproducen y reafirman los valores y significados por los cuales se legitima la apatía y adquiere dimensiones objetivas en las acciones de los agentes y en las instituciones. Las relaciones entre los agentes y la institución universitaria configuran el campo político universitario, las reglas del juego y la estructura y volumen de capital por los cuales se ubican de forma jerárquica dentro del campo. Los esquemas de percepción desde los cuales se piensa y actúa en relación a la participación política estudiantil, desde la autoridad y desde los estudiantes, explica la forma específica que adquiere la apatía dentro de la universidad y las relaciones de dominación dentro del campo político universitario. De este modo, la dominación de las autoridades universitarias casi sin reacción estudiantil, puede no ser cómoda para los est