David Velasco de la Fuente

Photovoltaic Power System With Battery Backup With Grid-Connection and Islanded Operation Capabilities

This paper presents the analysis, design, and experimentation results of a photovoltaic energy management system with battery backup. The proposed system is capable of both grid-connected and islanded operations. The main advantage of the proposed system is that, in grid-connected mode, the inverter works as a current source in phase with the grid voltage, injecting power to the grid and controlling the dc-link voltage. The dc/dc converter manages the battery charge. In islanded mode, the inverter control is reconfigured to work as a voltage source using droop schemes. The dc/dc converter controls the dc-link voltage to enable the maximum power point tracking reference to be followed. An operation protocol is proposed to ensure the quality of the energy supply and minimize energy loss. A battery bank is connected to the dc link as energy storage for islanded operation mode. The aim of this paper is to show that the proposed system performs correctly, without dangerous transients for the inverter or the loads. Simulation and experimental results on a 3-kW prototype show the feasibility of the proposed control strategy.

Reconfigurable Control Scheme for a PV Microinverter Working in Both Grid-Connected and Island Modes

In this paper, a photovoltaic (PV) microinverter capable of operating in both island mode and grid-connected mode by means of a reconfigurable control scheme is proposed. The main advantage of control reconfiguration is that in grid-connected mode, the microinverter works as a current source in phase with the grid voltage, injecting power to the grid. This is the operation mode of most commercial grid-connected PV microinverters. The idea is to provide those microinverters with the additional functionality of working in island mode without changing their control algorithms for grid-connected mode, which were developed and refined over time. It is proposed that in island mode, the microinverter control is reconfigured to work as a voltage source using droop schemes. These schemes consist in implementing P/Q strategies in the inverters, in order to properly share the power delivered to the loads. The aim of the paper is to show that the proposed control reconfiguration is possible without dangerous transients for the microinverter or the loads. Simulation and experimental results on an 180-W PV microinverter are provided to show the feasibility of the proposed control strategy.

Generation and Evaluation of a Genome-Scale Metabolic Network Model of Synechococcus elongatus PCC7942

The reconstruction of genome-scale metabolic models and their applications represent a great advantage of systems biology. Through their use as metabolic flux simulation models, production of industrially-interesting metabolites can be predicted. Due to the growing number of studies of metabolic models driven by the increasing genomic sequencing projects, it is important to conceptualize steps of reconstruction and analysis. We have focused our work in the cyanobacterium Synechococcus elongatus PCC7942, for which several analyses and insights are unveiled. A comprehensive approach has been used, which can be of interest to lead the process of manual curation and genome-scale metabolic analysis. The final model, iSyf715 includes 851 reactions and 838 metabolites. A biomass equation, which encompasses elementary building blocks to allow cell growth, is also included. The applicability of the model is finally demonstrated by simulating autotrophic growth conditions of Synechococcus elongatus PCC7942.

Automation on the Generation of Genome-Scale Metabolic Models

Nowadays, the reconstruction of genome-scale metabolic models is a nonautomatized and interactive process based on decision making. This lengthy process usually requires a full year of one persons work in order to satisfactory collect, analyze, and validate the list of all metabolic reactions present in a specific organism. In order to write this list, one manually has to go through a huge amount of genomic, metabolomic, and physiological information. Currently, there is no optimal algorithm that allows one to automatically go through all this information and generate the models taking into account probabilistic criteria of unicity and completeness that a biologist would consider. This work presents the automation of a methodology for the reconstruction of genome-scale metabolic models for any organism. The methodology that follows is the automatized version of the steps implemented manually for the reconstruction of the genome-scale metabolic model of a photosynthetic organism, Synechocystis sp. PCC6803. The steps for the reconstruction are implemented in a computational platform (COPABI) that generates the models from the probabilistic algorithms that have been developed. For validation of the developed algorithm robustness, the metabolic models of several organisms generated by the platform have been studied together with published models that have been manually curated. Network properties of the models, like connectivity and average shortest mean path of the different models, have been compared and analyzed.

Review of Anti-Islanding Methods: Analysis by Figures of Merit Tools for Controllers Reconfiguration in Microgrids

This paper presents the analysis and comparison of the main active techniques for islanding detection applied to microgrids. The perturbation produced in the system by the methods is studied when the islanding situation occurs. The aim of this study is to minimize the effects of the transition between islanded and grid-connected states. The algorithms mentioned in this paper were simulated in PSIMTM and compared to establish their advantages and disadvantages. The figure of merit tool is used to compare the systems.

Análisis de un método activo para la detección de isla basado en la perturbación de la fase en el pll y comparación con otros métodos activos

En este articulo se propone un metodo nuevo para la deteccion de isla en sistemas de generacion distribuida. Dicho procedimiento se basa en la introduccion de una perturbacion a la salida del inversor con el fin de observar el comportamiento de la tension en el punto de acople comun (PCC), la cual dependera de la impedancia conectada ⎯al PCC⎯ en la situacion de isla. Asi mismo, se efectuo un analisis comparativo entre las principales tecnicas activas residentes en el inversor para deteccion de isla y su similitud con la propuesta. Los algoritmos mencionados en este articulo fueron simulados en PSIMTM y comparados para establecer sus ventajas y desventajas (basados en estandares IEEE).