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International audience; There is a growing research interest in studying microgrids in rural areas as a means to promote energy access. These microgrids could be the key to energy access on a global scale because of their many advantages compared to classic grid expansion. Despite all these qualities, feedback from microgrids in rural areas shows that most fail to reach sustainability, but the reasons for their long-term failure are still not a consensus in the literature. This work intends to contribute to understanding microgrids' sustainability and their expansion by modelling them using a systemic vision approach. For this purpose, we propose a diagnosis tool that includes energy, financial, information and social aspects. A series of study cases are analyzed through this approach, showing it as a possible diagnostic tool for microgrids in the short and long term.

International audience; This work presents a contribution to the automatic design of modular power converters based on the associations of standardized conversion cells. All conversion cells studied in this work were fabricated, tested and characterized, and statistical models are derived to represent their behavior. These statistical models were based on experimental data to predict with precision the behavior of any power converter built from a large number of identical conversion cells in any type of association. This work focuses on the characterization methodology and the modeling method implemented for low power, air-cooled standard conversion cells along with further details of the automated design method.

International audience; More than a billion people still lack access to electricity inrural regions throughout the world. Rural electrification is thepart of the Development Engineering rearch field that studies thisissue. In theory, rural electrification is achieved through energytiers, going from low to high. In practice, low tier stand-alonesystems are very difficult to upgrade to higher-tiers micro-grids.This constitutes amissing linkthat locks millions in poverty. Inthis work, modular power electronics are analyzed as the potentialsolution to thismissing link. This paper proposes a theoreticalframework to analyze modular power converters for multi-tierrural micro-grids expansion.Five different tier scenarios areextracted from the literature and used to analyze two modularpower converter topologies. The results are summarized throughthe ”expansion signature” tool which can be used as a basis forfuture analysis

International audience

International audience; This paper presents a methodology to derive mathematical models of active power components based on statistical theory and datasheet parameter extraction. The models have the objective of providing reliable data of gate-to-drain voltage (VGD), gate-to-source voltage (VGS) and direct current (ID) for nominal operating temperature range using only datasheet points. For achieving that, statistical learning theory is used to fit models in a reliable and systematic way. Besides predicting accurately static operation points, the proposed model can be used to estimate dynamics and switching losses in power switches. The model is validated using static and dynamic data available in a datasheet. The model is used to analyze a MOSFET behavior in typical power electronics applications. Finally, it is discussed the data availability in datasheets in order to easily create accurate models.

International audience

International audience

La red WindEmpowerment (WE) es una organización civil internacional que fomenta el conocimiento compartido y la utilización de fuentes renovables (sobre todo eólica de baja escala) para resolver problemas de electrificación rural. Si bien se utilizan diseños electro-mecánicos abiertos (turbina Piggot y otros), los conversores de electrónica de potencia en general no lo son. El presente Proyecto busca desarrollar, a través de la implementación colaborativa, una alternativa de diseño abierta y pública que permita a grupos o individuos con algún conocimiento técnico implementar sus propias soluciones, sea para ONGs que buscan hacer llegar una solución energética en sitios aislados, como también a fabricantes que al adherir al concepto modular y estándar, provean alternativas compatibles. La iniciativa, en la que participan ONGs, Universidades y Empresas vinculadas a las energías renovables de Francia, Argentina, Perú, Austria e Inglaterra y que obtuvo financiamiento a inicios de 2016 a través de WISIONS, enfatiza la participación de becarios estudiantiles de ingeniería en pasantías. En el presente trabajo se describen los pasos iniciales y alcances previstos para el desarrollo conjunto de un estándar para la producción de conversores de electrónica de potencia modulares., This paper presents the preliminary advances of a project to develop open-source and open-hardware power modules for small-scale wind and photovoltaic rural electrification systems. Design criteria and expected solutions, as well as a series of implementation issues are discussed, together with the probable sequence of experiments required to establish a usable result in the near future., Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES)

Photovoltaic energy rates among the most mature renewable sources currently available in the market. However, its growing use in urban environment has met with an important obstacle: shadows. Their study present a two-fold challenge: understanding what they are and how they can be mitigated. While many authors have proposed different solutions for this problem, very few have tried to understand the shadow in its complexity. This thesis seeks, at the same time, a comprehensive view on the shadow itself while proposing a new solution to mitigate it. The comprehensive view of the shadow is proposed through an intermittency theory, where its optical properties and electrical consequences are taken into account. This theory provides the elements to review the current literature into a new perspective. The available solutions are, then, divided into two families: series and parallel. Series solutions employ several structures, each extracting the power of a reduced number of photovoltaic cells. As a consequence the impact of the shadow is restricted. Parallel solutions use few structures to redistribute the current between shaded and unshaded photovoltaic cells, thus sharing the impact of the shadow. The new solution proposed to mitigate the shadow is a parallel system called PV Equalizer. Inspired from its battery equivalent, it has a different topology with a high integration potential, easily scalable but seemingly difficult to control. To prove its concept, a study is conducted to determine its functions. It is found to be capable of not only mitigating but also detecting the shadow. These functions are characterized and their results used to conceive a control algorithm. Finally, this algorithm is tested and validated in a prototype under real operating conditions. The system detected the presence of the shadow, chose the best way to mitigate it and raised the power output by roughly 40 %., L'énergie photovoltaïque est à nos jours l'une des sources intermittentes les plus développée. Plusieurs années de recherche confèrent une importante maturité à la fois aux modules et aux systèmes de extraction et traitement de son électricité. Cependant, il lui reste encore un important obstacle à franchir avant son utilisation à large échelle : la présence des ombres. Alors que plusieurs solutions ont été déjà proposées pour ce problème, la recherche sur l'ombre en tel que phénomène complexe reste embryonnaire. Cette thèse a pour but de combler ce besoin à la fois en étudiant la présence d l'ombre et en y proposant une nouvelle réponse. L'étude de l'ombre comprend la proposition d'une théorie sur l'intermittence qui prend en compte des aspect à la fois électriques et optiques. A travers de cette théorie, une relecture de la littérature est aussi proposée et donne lieu à une classification des solutions existantes en séries ou parallèles. Les solutions séries utilisent plusieurs structures d'électronique de puissance pour extraire l'énergie d'un nombre plus restreint des cellules photovoltaïques et par conséquent y confinent l'impact de l'ombre. En contre partie, les solutions parallèles utilisent des structures spéciales pour redistribuer le courant parmi les cellules ombrées et illuminées, ce qui amène à lŠeffacement de l'ombre. La nouvelle réponse à l'ombre proposée dans ce travail s'agit d'une structure parallèle à forte potentiel d'intégration monolithique. Inspirée de son équivalent pour les batteries, cette nouvelle topologie est applicable à plusieurs échelles mais sa commande reste un aspect à maîtriser. Son concept de base est validé au niveau d'un seul module photovoltaïque par la création d'un prototype et une validation expérimentale. Sa commande y est ensuite développée, testée et validée. Le système est capable de détecter la présence de l'ombre, choisir la meilleure stratégie pour la mitiger et l'implémenter en toute autonomie. Le résultat final est une augmentation de la puissance de sortie d'environ 40% dans certains cas.

Photovoltaic energy rates among the most mature renewable sources currently available in the market. However, its growing use in urban environment has met with an important obstacle: shadows. Their study present a two-fold challenge: understanding what they are and how they can be mitigated. While many authors have proposed different solutions for this problem, very few have tried to understand the shadow in its complexity. This thesis seeks, at the same time, a comprehensive view on the shadow itself while proposing a new solution to mitigate it. The comprehensive view of the shadow is proposed through an intermittency theory, where its optical properties and electrical consequences are taken into account. This theory provides the elements to review the current literature into a new perspective. The available solutions are, then, divided into two families: series and parallel. Series solutions employ several structures, each extracting the power of a reduced number of photovoltaic cells. As a consequence the impact of the shadow is restricted. Parallel solutions use few structures to redistribute the current between shaded and unshaded photovoltaic cells, thus sharing the impact of the shadow. The new solution proposed to mitigate the shadow is a parallel system called PV Equalizer. Inspired from its battery equivalent, it has a different topology with a high integration potential, easily scalable but seemingly difficult to control. To prove its concept, a study is conducted to determine its functions. It is found to be capable of not only mitigating but also detecting the shadow. These functions are characterized and their results used to conceive a control algorithm. Finally, this algorithm is tested and validated in a prototype under real operating conditions. The system detected the presence of the shadow, chose the best way to mitigate it and raised the power output by roughly 40 %., L'énergie photovoltaïque est à nos jours l'une des sources intermittentes les plus développée. Plusieurs années de recherche confèrent une importante maturité à la fois aux modules et aux systèmes de extraction et traitement de son électricité. Cependant, il lui reste encore un important obstacle à franchir avant son utilisation à large échelle : la présence des ombres. Alors que plusieurs solutions ont été déjà proposées pour ce problème, la recherche sur l'ombre en tel que phénomène complexe reste embryonnaire. Cette thèse a pour but de combler ce besoin à la fois en étudiant la présence d l'ombre et en y proposant une nouvelle réponse. L'étude de l'ombre comprend la proposition d'une théorie sur l'intermittence qui prend en compte des aspect à la fois électriques et optiques. A travers de cette théorie, une relecture de la littérature est aussi proposée et donne lieu à une classification des solutions existantes en séries ou parallèles. Les solutions séries utilisent plusieurs structures d'électronique de puissance pour extraire l'énergie d'un nombre plus restreint des cellules photovoltaïques et par conséquent y confinent l'impact de l'ombre. En contre partie, les solutions parallèles utilisent des structures spéciales pour redistribuer le courant parmi les cellules ombrées et illuminées, ce qui amène à l'effacement de l'ombre. La nouvelle réponse à l'ombre proposée dans ce travail s'agit d'une structure parallèle à forte potentiel d'intégration monolithique. Inspirée de son équivalent pour les batteries, cette nouvelle topologie est applicable à plusieurs échelles mais sa commande reste un aspect à maîtriser. Son concept de base est validé au niveau d'un seul module photovoltaïque par la création d'un prototype et une validation expérimentale. Sa commande y est ensuite développée, testée et validée. Le système est capable de détecter la présence de l'ombre, choisir la meilleure stratégie pour la mitiger et l'implémenter en toute autonomie. Le résultat final est une augmentation de la puissance de sortie d'environ 40% dans certains cas.

International audience

Almost 1 billion people still have no access to energy, many due to cost of expanding the electricity grid to rural areas. This PhD thesis analyses the barriers to renewable energy in rural areas and examines load management algorithms as means of cheaply improving power output from renewables. The thesis shows that many current obstacles stem from socioeconomic factors, and these along with technical aspects are tackled in a prototype installation of an energy system in an Indian village. Fast 1 Milliarde Menschen haben keinen Energiezugang, viele aufgrund der Aufbaukosten des Stromnetzes in ländlichen Gebieten. Diese Dissertation analysiert Hindernisse für erneuerbare Energien in ländlichen Gebieten und untersucht Lastmanagement-Algorithmen zur billigen Verbesserung derer Stromerzeugung. Die Arbeit zeigt, dass viele Hindernisse auf sozioökonomische Faktoren zurückzuführen sind. Diese werden zusammen mit technischen Aspekten in einer Prototypinstallation in Indien angegangen.