Micro-inversores: principales topologías

Este trabajo presenta una revisión bibliográfica de las diferentes configuraciones para Sistemas Fotovoltaicos Conectados a Red (SFCR) y las diversas topologías utilizadas en el diseño de micro-inversores (MI). Las topologías para MI que se presentan se encuentran clasificadas en tres grupos: MI con vínculo de corriente continua, MI con pseudo vínculo de corriente continua y MI sin vínculo de corriente continua. Como parte del reporte, se expondrán las configuraciones circuitales que adoptan las etapas de potencia de las diferentes topologías así como también sus principales características

A review of grid-tied converter topologies used in photovoltaic systems

This study provides review of grid-tied architectures used in photovoltaic power systems, classified by the granularity level at which maximum power point tracking (MPPT) is applied. Grid-tied PV power systems can be divided into two main groups, namely centralized MPPT (CMPPT) and distributed MPPT (DMPPT). The DMPPT systems are further classified according to the levels at which MPPT can be applied, i.e. string, module, submodule, and cell level. Typical topologies for each category are also introduced, explained and analyzed. The classification is intended to help readers understand the latest developments of grid-tied PV power systems and inform research directions

Single Stage Flyback Micro-Inverter for Solar Energy Systems

ABSTRACT Solar energy systems based on photovoltaic (PV) cells have attracted considerable interest in recent years due to their promise of clear and seemingly limitless generated energy. Solar energy systems based on micro-inverter architectures are gaining in popularity as they are less prone to shading and PV cell malfunction since each solar panel in a system has its own low power inverter. A number of micro-inverters are single stage flyback inverters that are based on the DC-DC flyback topologies. There have been numerous papers on the topic of how to improve the efficiency of dc-dc flyback converters but as far as improving the efficiency of dc-ac flyback micro-inverter is concerned, comparatively less investigation on efficiency improvement has been performed. A low cost technique for improving the efficiency of a basic dc-ac flyback micro-inverter is proposed in the paper. The proposed efficiency improving technique is based on a simple snubber, consisting of just a few passive elements. In the thesis, the flyback micro-inverter with the passive snubber is presented; the modes of operation of the converter are discussed as well as the design of the converter with the passive snubber. Experimental results obtained from a lab prototype are presented as well. A second novel technique for improving the efficiency of a single stage flyback micro-inverter is also proposed. The technique is based on combining the simple passive snubber with a variable frequency control zero-voltage switching (ZVS) technique. In the thesis, the operation of the micro-inverter with both the passive snubber and the ZVS technique is explained and the design of the converter is discussed. Experimental results obtained from a lab prototype are presented to confirm the effectiveness of the both the techniques

Análisis del modelo de estado estable y transitorio de fuentes de generación eléctrica, para simulación de un sistema de prueba en media tensión

En el entorno de los sistemas eléctricos de potencia, la generación de energía eléctrica evolucionó en base a centrales hidroeléctricas, termoeléctricas y nucleares, las cuales, aprovechan la energía de una fuente primaria para suplir energía eléctrica a mediano o bajo costo. Este esquema o matriz de generación, aun es la principal fuente de energía eléctrica para la mayoría de países. Lo anterior, por tratarse de tecnologías funcionales y cuyo avance tecnológico ha permitido establecer un nivel elevado de seguridad y confiabilidad para generar energía. No obstante, las nuevas tecnologías también han hecho posible que sistemas de generación que en otra época se consideraban inviables, puedan ser estudiados e implementados con relativa facilidad. Así pues, los sistemas de generación están incursionando en la generación renovable, la cual, impulsada por la conciencia social sobre el cuidado del medio ambiente, el bajo costo de generación y la relativa facilidad en la implementación, ha escalado en importancia hasta volverse representativa en algunos países desarrollados. Como ejemplo, se tiene en [1], una breve descripción del mercado de energía en Alemania. Allí, se aprecia la importancia de la generación renovable en la bolsa de energía, pues es incluida en la regulación del mercado intradiario para integrar la generación solar al sistema de potencia. Así, la generación solar en Alemania contribuyó en el 2011 con 20 % de la energía transada en el mercado intradiario. También, se tiene en [2], el caso de España, cuya generación eólica es la segunda fuente de generación de energía eléctrica, teniendo una potencia eólica instalada de 23.026 GW Entonces, el mercado eléctrico, los entes reguladores y las entidades presentes en el proceso de generación, transmisión y distribución de energía eléctrica, están cada vez más interesados en la implementación y regulación de la generación renovable..

Photovoltaic generation with energy storage integrated into the electric grid: modelling, simulation and experimentation

Esta tese apresenta o trabalho e resultados da investigação desenvolvida sobre conversão fotovoltaica com armazenamento de energia integrado em rede elétrica. Começa por apresentar a modelação, simulação e validação da conversão fotovoltaica e inversores com injeção para a rede. Descreve também seguidamente o processo de conceção, construção, comissionamento e desenvolvimento experimental das infraestruturas hoje existentes na Cátedra Energias Renováveis da Universidade de Évora, no que diz respeito às duas microgrids desenvolvidas no âmbito do projeto europeu PVCROPS. Estas microgrids são compostas, de forma geral, por um elemento de produção fotovoltaica, um elemento de armazenamento de energia, uma ligação à rede e um sistema de controlo e datalogging. Relativamente ao armazenamento de energia, esta tese aborda e caracteriza ainda as duas tecnologias instaladas: a bateria de iões de lítio e a bateria de fluxo redox de vanádio. Estas microgrids servem assim para implementação e validação de uma estratégia de gestão de energia tendo como objetivo a maximização do autoconsumo, cujos conteúdos são apresentados no capítulo 4. Depois das conclusões, no último capítulo, apontam-se ainda as linhas de investigação futuras de maior potencial, na sequência do trabalho desenvolvido e apresentado nesta tese; Photovoltaic generation with energy storage integrated into the electric grid: Modelling, simulation and experimentation Abstract: This thesis presents the work and results of the research developed on photovoltaic conversion with energy storage integrated into the electric grid. It begins by presenting the modeling, simulation and validation of the photovoltaic conversion and inverters with injection into the electric grid. It also describes the process of design, construction, commissioning and experimental development of the existing infrastructures in the Renewable Energies Chair of the University of Évora, with respect to the two microgrids developed under the European project PVCROPS. These microgrids are generally composed by a photovoltaic production element, an energy storage element, a grid connection and a control and datalogging system. Regarding energy storage, this thesis also discusses and characterizes the two installed technologies: the lithium-ion battery and the redox-flow vanadium battery. These microgrids thus serve to implement and validate an energy management strategy with the objective of maximizing self-consumption, the contents of which are presented in Chapter 4. Following the conclusions, in the last chapter are pointed the future research lines of greater potential, following the work developed and presented in this thesis