Experimental measurement system and neural network model to simulate photovoltaic modules

Para la simulación de la curva l-V de los módulos fotovoltaicos se ha propuesto la utilización de un perceptrón multicapa. Se han evaluado cómo contribuyen a esta simulación distintos parámetros de entrada, como son el ángulo de incidencia, el Índice de transparencia atmosférico y la distribución espectral de la radiación. Fecha de lectura de Tesis Doctoral: 30 de septiembre 2011.El objetivo de esta tesis es el desarrollo de una metodología de medida, caracterización y simulación de módulos fotovoltaicos que pueda ser de utilidad para los investigadores e ingenieros del campo de la tecnología solar fotovoltaica. Para la parte de medida se ha desarrollado un nuevo sistema de medida de curvas l-V para módulos fotovoltaicos. En la parte de caracterización y simulación, se ha propuesto un modelo basado en redes neuronales que permite extrapolar estas curvas a distintas condiciones reales de funcionamiento. El sistema de medida propuesto resuleve los problemas detectados en los métodos que se están utilizando en la actualidad. En concreto, y como más importante deficiencia a la que se da solución en esta tesis, está el problema de obtener los valores de los dos parámetros que configuran estas curvas, a saber, corriente y tensión, de manera simultánea. El sistema propuesto está basado en la utilización de una carga electrónica de cuatro cuadrantes y dos multimetros digitales sincronizados con un generador de ondas que crea una señal cuadrada para disparar ambos multímetros. Este método de sincronización asegura que las medidas de tensión y corriente se efectúan de manera simultánea: esto no se asegura con otros métodos previamente usados que utilizan una sincronización vía GPIB. Además, se hace una propuesta de utilizar esquemas XML para el formato de los datos registrados en laboratorios fotovoltaicos. Este formato puede contribuir a una estandarización de los datos que se utilizan para la caracterización de módulos fotovoltaicos por distintos laboratorios de medida. Esto facilitará el intercambio de información entre estos laboratorios

New software tool to characterize photovoltaic modules from commercial equipment

A software platform has been developed in order to unify the different measurements obtained from different manufacturers in the photovoltaic system laboratory of the University of Malaga, Spain. These measurements include the current-voltage curve of PV modules and several meteorological parameters such as global and direct irradiance, temperature and spectral distribution of solar irradiance. The measurements are performed in an automated way by a stand-alone application that is able to communicate with a pair of multimeters and a bipolar power supply that are controlled in order to obtain the current–voltage pairs. In addition, several magnitudes, that can be configured by the user, such as irradiance, module temperature or wind speed, are incorporated to register the conditions of each measurement. Moreover, it is possible to attach to each curve the spectral distribution of the solar radiation at each moment. Independently of the source of the information, all these measurements are stored in a uniform relational database. These data can be accessed through a public web site that can generate several graphics from the data.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Junta de Andalucía. Proyecto de Excelencia P11-RNM-711

Characterisation of hourly temperature of a thin-film module from weather conditions by artificial intelligence techniques

The aim of this paper is the use and validation of artificial intelligence techniques to predict the temperature of a thin-film module based on tandem CdS/CdTe technology. The cell temperature of a module is usually tens of degrees above the air temperature, so that the greater the intensity of the received radiation, the greater the difference between these two temperature values. In practice, directly measuring the cell temperature is very complicated, since cells are encapsulated between insulation materials that do not allow direct access. In the literature there are several equations to obtain the cell temperature from the external conditions. However, these models use some coefficients which do not appear in the specification sheets and must be estimated experimentally. In this work, a support vector machine and a multilayer perceptron are proposed as alternative models to predict the cell temperature of a module. These methods allow us to achieve an automatic way to learn only from the underlying information extracted from the measured data, without proposing any previous equation. These proposed methods were validated through an experimental campaign of measurements. From the obtained results, it can be concluded that the proposed models can predict the cell temperature of a module with an error less than 1.5 °C.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Photovoltaic module series resistance identification at its maximum power production

Analysis of measured current–voltage curves offers a cost-effective option for online condition monitoring of photovoltaic (PV) modules. The current–voltage curves of PV modules can be modeled accurately using the well-known electrical single-diode model. In practical applications, condition monitoring should be based on measurements performed near the maximum power point (MPP) by affecting PV power production negligibly. The series resistance is the most important single-diode model parameter in assessing the condition of PV modules; this paper proposes a novel method for its determination by using measurements acquired near the MPP only. The proposed method can be used with any series resistance identification procedure based on current–voltage curve measurements. The proposed method is experimentally validated using current–voltage curves of two PV modules measured in Malaga, Spain. This study allows to assess that the series resistance can be accurately determined from measurements performed near the MPP. Especially the results obtained with an ISOFOTON ISF-145 PV module are very promising: the scaled series resistances obtained from measurements done without lowering the PV power more than 2% of the maximum power differ on the average by no more than 2% of the series resistances obtained from the whole current–voltage curves.Peer reviewe

Analysis of the degradation of amorphous silicon-based modules after 11 years of exposure by means of IEC60891:2021 procedure 3

The degradation of two amorphous silicon-based photovoltaic (PV) modules, namely, of single junction amorphous silicon (a-Si) and of micromorph tandem (a-Si/μ-Si), after 11 years of exposure in the south of Spain is analyzed. Their I-V curves were measured outdoors to study the changes of the electrical parameters in the course of three different periods: during the initial days of exposure, during the first year, and in the subsequent 10-year period. The translation of the curves to an identical set of operating conditions, which enables a meaningful comparison, was done by the dif ferent correction procedures described in the standard IEC60891:2021, including the procedure 3, which does not require the knowledge of module parameters, whose values are typically not available. The annual power degradation rates over the entire 11-year period are 1.12% for the a-Si module, which is 3.02% for the first year, and 0.98% for the a-Si/μ-Si, which is 2.29% for the initial yearThis work is supported by Ministero dell'Istruzione, dell'Università e della Ricerca (Italy) (grant PRIN2020-HOTSPHOT 2020LB9TBC and grant PRIN2017-HEROGRIDS 2017WA5ZT3_003); Università degli Studi di Salerno (FARB funds); Ministerio de Ciencia, Innovacion y Universidades (Spain) (grant RTI2018-095097-B-I0)

A low-cost photovoltaic emulator for static and dynamic evaluation of photovoltaic power converters and facilities

In testing maximum power point tracking (MPPT) algorithms running on electronic power converters for photovoltaic (PV) applications, either a PV energy source (PV module or PV array) or a PV emulator is required. With a PV emulator, it is possible to control the testing conditions with accuracy so that it is the preferred option. The PV source is modeled as a current source; thus, the emulator has to work as a current source dependent on its output voltage. The proposed emulator is a buck converter with an average current mode control loop, which allows testing the static and dynamic performance of PV facilities up to 3 kW. To validate the concept, the emulator is used to evaluate the MPPT algorithm of a 230-W experimental microinverter working from a single PV module.This work is supported by the Spanish Ministry of Science and Innovation under grant ENE2009-13998-C02-02.González Medina, R.; Patrao Herrero, I.; Garcerá Sanfeliú, G.; Figueres Amorós, E. (2014). A low-cost photovoltaic emulator for static and dynamic evaluation of photovoltaic power converters and facilities. Progress in Photovoltaics. 22(2):227-241. https://doi.org/10.1002/pip.2243S227241222Prapanavarat, C., Barnes, M., & Jenkins, N. (2002). Investigation of the performance of a photovoltaic AC module. IEE Proceedings - Generation, Transmission and Distribution, 149(4), 472. doi:10.1049/ip-gtd:20020141Durán, E., Andújar, J. M., Galán, J., & Sidrach-de-Cardona, M. (2009). Methodology and experimental system for measuring and displayingIâ Vcharacteristic curves of PV facilities. Progress in Photovoltaics: Research and Applications, 17(8), 574-586. doi:10.1002/pip.909Piliougine, M., Carretero, J., Mora-López, L., & Sidrach-de-Cardona, M. (2011). Experimental system for current-voltage curve measurement of photovoltaic modules under outdoor conditions. Progress in Photovoltaics: Research and Applications, 19(5), 591-602. doi:10.1002/pip.1073Sanchis, P., López, J., Ursúa, A., Gubía, E., & Marroyo, L. (2007). On the testing, characterization, and evaluation of PV inverters and dynamic MPPT performance under real varying operating conditions. Progress in Photovoltaics: Research and Applications, 15(6), 541-556. doi:10.1002/pip.763Kjaer, S. B., Pedersen, J. K., & Blaabjerg, F. (2005). A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules. IEEE Transactions on Industry Applications, 41(5), 1292-1306. doi:10.1109/tia.2005.853371Kondrath, N., & Kazimierczuk, M. K. (2012). Comparison of Wide- and High-Frequency Duty-Ratio-to-Inductor-Current Transfer Functions of DC–DC PWM Buck Converter in CCM. IEEE Transactions on Industrial Electronics, 59(1), 641-643. doi:10.1109/tie.2011.2134053Tan, Y. T., Kirschen, D. S., & Jenkins, N. (2004). A Model of PV Generation Suitable for Stability Analysis. IEEE Transactions on Energy Conversion, 19(4), 748-755. doi:10.1109/tec.2004.827707Villalva, M. G., Gazoli, J. R., & Filho, E. R. (2009). Comprehensive Approach to Modeling and Simulation of Photovoltaic Arrays. IEEE Transactions on Power Electronics, 24(5), 1198-1208. doi:10.1109/tpel.2009.2013862Shengyi Liu, & Dougal, R. A. (2002). Dynamic multiphysics model for solar array. IEEE Transactions on Energy Conversion, 17(2), 285-294. doi:10.1109/tec.2002.1009482Mekki, H., Mellit, A., Kalogirou, S. A., Messai, A., & Furlan, G. (2010). FPGA-based implementation of a real time photovoltaic module simulator. Progress in Photovoltaics: Research and Applications, 18(2), 115-127. doi:10.1002/pip.950Mohan N Undeland T Robbins W Power electronics: converters, applications and design (3rd edn) 2003Garcera, G., Figueres, E., Pascual, M., & Benavent, J. M. (2004). Robust model following control of parallel buck converters. IEEE Transactions on Aerospace and Electronic Systems, 40(3), 983-997. doi:10.1109/taes.2004.1337469Vorperian, V. (1990). Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode. IEEE Transactions on Aerospace and Electronic Systems, 26(3), 490-496. doi:10.1109/7.106126Packiam, P., Jain, N. K., & Singh, I. P. (2011). Microcontroller-based simple maximum power point tracking controller for single-stage solar stand-alone water pumping system. Progress in Photovoltaics: Research and Applications, n/a-n/a. doi:10.1002/pip.1207Chuanzong F Shiping S Simulation studying of MPPT control by a new method for photovoltaic power system Electrical and Control Engineering (ICECE), 2011 International Conference on 2011 10.1109/ICECENG.2011.605791