Modeling of a Computer Using the Norton Model for Harmonic Analysis

The Norton model of a personal computer for harmonic analysis is presented in this paper. The parameters of the model are estimated from two experiments, in which the computer is powered by two different voltages. The model is simulated and the current and voltage waveforms are compared with the experimental waves. The results show that Norton model is valid to represent a personal computer because the error index of the current and voltage waveforms and harmonic spectrums is lower than 8.5%.The Norton model of a personal computer for harmonic analysis is presented in this paper. The parameters of the model are estimated from two experiments, in which the computer is powered by two different voltages. The model is simulated and the current and voltage waveforms are compared with the experimental waves. The results show that Norton model is valid to represent a personal computer because the error index of the current and voltage waveforms and harmonic spectrums is lower than 8.5%

Modeling of a Computer Using the Norton Model for Harmonic Analysis

The Norton model of a personal computer for harmonic analysis is presented in this paper. The parameters of the model are estimated from two experiments, in which the computer is powered by two different voltages. The model is simulated and the current and voltage waveforms are compared with the experimental waves. The results show that Norton model is valid to represent a personal computer because the error index of the current and voltage waveforms and harmonic spectrums is lower than 8.5%.The Norton model of a personal computer for harmonic analysis is presented in this paper. The parameters of the model are estimated from two experiments, in which the computer is powered by two different voltages. The model is simulated and the current and voltage waveforms are compared with the experimental waves. The results show that Norton model is valid to represent a personal computer because the error index of the current and voltage waveforms and harmonic spectrums is lower than 8.5%

Distributed maximum power point tracking with overvoltage protection for pv systems

This paper presents an integral solution of the overvoltage problem caused by mismatched conditions when DC-DC converter outputs of PV systems are connected in series, and a distributed maximum power point tracking architecture is implemented. The operating conditions that cause the overvoltage problem are discussed in detail and the consequences of the overvoltage problem are illustrated. The proposed solution is based on a structure that includes a non-linear controller, two linear controllers, and a maximum power point tracking algorithm. Such a solution makes it possible to regulate the PV voltage according to the MPPT controller commands and to limit the DC-DC converter output voltage to avoid damages. The non-linear control structure is experimentally validated with a boost converter and a BP585 PV panel. Simulation results show that the proposed integral solution allows the operation of PV panels in the feasible maximum power point and protects the integrity of the DC-DC converters, avoiding the overvoltage problem caused by mismatched conditions

Estimating the produced power by photovoltaic installations in shaded environments

A model to improve the estimation of the power and energy from photovoltaic installations under dynamic shading conditions is proposed in this paper. The model considers the shaded profile in each photovoltaic module and the temperature profile to update the model parameters of each photovoltaic module. The impact of dynamic shades on the power production is analyzed, illustrating the large errors introduced by classical prediction approaches, which consider non-shading at all or average shading.  Moreover, a procedure to model the shades profile in any environment is described and illustrated. Finally, experimental irradiance and environment temperature profiles are used to evaluate the performance of the proposed model in contrast with the classical approaches. The results illustrate that the classical approaches overestimate the power produced by the photovoltaic array, in contrast with the power produced by the proposed model

Modelo equivalente de un sistema trifásico de generación fotovoltaica para analizar variaciones de voltaje en un sistema de distribución radial

In this paper, the modelling of a three-phase photovoltaic system, for analyzing voltage variation in a radial distribution system, is presented. The radial distribution system is represented by a benchmark which is widely used in the analysis of distribution systems with distributed generation, and electrical microgrids. The parameters estimation of this model is performed by selecting the aerial distribution of conductors and then calculating the sequence components. Moreover, a model of a three-phase photovoltaic generation system for analyzing voltage variations is proposed. The model represents an array of photovoltaic panels, a dc/dc converter with its control system, and a three-phase inverter. The software MATLAB/Simulink is chosen to simulate both the distribution and the photovoltaic systems. All the components of the three-phase photovoltaic system are parametrized with information of commercial equipment. To facilitate the implementation of the system model in the analysis program, reduced models of its components are selected. Finally, the proposed model of the three-phase photovoltaic system is validated by simulating single-phase faults along the feeder and changes of irradiance over the photovoltaic generators and observing the voltage behavior in one node of the distribution system. The results show that irradiance changes and single-phase faults affect the voltage behavior depending on the photovoltaic penetration level and the generators location.En este artículo se presenta el modelado de un sistema trifásico de generación fotovoltaica para analizar variaciones de voltaje sobre un sistema de distribución radial. El sistema de distribución radial se representa con un modelo de referencia, el cual se utiliza ampliamente en el análisis de sistemas de distribución con generación distribuida y microrredes eléctricas. La estimación de parámetros de este modelo se completa seleccionando la distribución aérea de los conductores y posteriormente calculando sus componentes de secuencia. También se propone el modelo de un sistema trifásico de generación fotovoltaica para analizar la variación del voltaje. El modelo representa un arreglo de paneles fotovoltaicos, un convertidor dc/dc con su sistema de control y un inversor trifásico. Se selecciona el software Simulink de MATLAB para simular el sistema de distribución y el sistema de fotovoltaico. Los componentes del sistema trifásico de generación fotovoltaica son parametrizados con información de equipos comerciales. Para facilitar la implementación del modelo del sistema trifásico de generación fotovoltaica en los softwares de análisis, se seleccionan modelos reducidos de los componentes. Finalmente, el modelo propuesto para el sistema trifásico de generación fotovoltaica se valida simulando fallas monofásicas a lo largo del alimentador y cambios de irradiación solar sobre los generadores fotovoltaicos y observando el comportamiento del voltaje en un nodo del sistema de distribución. Los resultados muestran que el cambio en la irradiación solar y las fallas monofásicas influyen sobre el comportamiento del voltaje dependiendo del nivel de penetración fotovoltaica y la ubicación de los generadores

DC-DC converters in wind systems for micro-generation: a systematic review

A literature review about wind systems for micro-generation is presented in this paper. The review is made analyzing four topics of the wind systems: wind system topologies, modeling, power converters design, and power converters control. The review results are presented in two matrices, which highlight research problems that should be addressed

Modelo equivalente de un sistema trifásico de generación fotovoltaica para analizar variaciones de voltaje en un sistema de distribución radial

In this paper, the modelling of a three-phase photovoltaic system, for analyzing voltage variation in a radial distribution system, is presented. The radial distribution system is represented by a benchmark which is widely used in the analysis of distribution systems with distributed generation, and electrical microgrids. The parameters estimation of this model is performed by selecting the aerial distribution of conductors and then calculating the sequence components. Moreover, a model of a three-phase photovoltaic generation system for analyzing voltage variations is proposed. The model represents an array of photovoltaic panels, a dc/dc converter with its control system, and a three-phase inverter. The software MATLAB/Simulink is chosen to simulate both the distribution and the photovoltaic systems. All the components of the three-phase photovoltaic system are parametrized with information of commercial equipment. To facilitate the implementation of the system model in the analysis program, reduced models of its components are selected. Finally, the proposed model of the three-phase photovoltaic system is validated by simulating single-phase faults along the feeder and changes of irradiance over the photovoltaic generators and observing the voltage behavior in one node of the distribution system. The results show that irradiance changes and single-phase faults affect the voltage behavior depending on the photovoltaic penetration level and the generators location.En este artículo se presenta el modelado de un sistema trifásico de generación fotovoltaica para analizar variaciones de voltaje sobre un sistema de distribución radial. El sistema de distribución radial se representa con un modelo de referencia, el cual se utiliza ampliamente en el análisis de sistemas de distribución con generación distribuida y microrredes eléctricas. La estimación de parámetros de este modelo se completa seleccionando la distribución aérea de los conductores y posteriormente calculando sus componentes de secuencia. También se propone el modelo de un sistema trifásico de generación fotovoltaica para analizar la variación del voltaje. El modelo representa un arreglo de paneles fotovoltaicos, un convertidor dc/dc con su sistema de control y un inversor trifásico. Se selecciona el software Simulink de MATLAB para simular el sistema de distribución y el sistema de fotovoltaico. Los componentes del sistema trifásico de generación fotovoltaica son parametrizados con información de equipos comerciales. Para facilitar la implementación del modelo del sistema trifásico de generación fotovoltaica en los softwares de análisis, se seleccionan modelos reducidos de los componentes. Finalmente, el modelo propuesto para el sistema trifásico de generación fotovoltaica se valida simulando fallas monofásicas a lo largo del alimentador y cambios de irradiación solar sobre los generadores fotovoltaicos y observando el comportamiento del voltaje en un nodo del sistema de distribución. Los resultados muestran que el cambio en la irradiación solar y las fallas monofásicas influyen sobre el comportamiento del voltaje dependiendo del nivel de penetración fotovoltaica y la ubicación de los generadores

Técnicas para modelar sistemas fotovoltaicos bajo sombreado parcial

Context: The energy produced by photovoltaic (PV) systems operating under partial shading conditions depends on the connections between the modules and the shading pattern. Several mathematical models have been proposed to address this topic exhibiting different compromises between accuracy, calculation speed and PV model complexity. However, it is not evident how to choose a model for a given application to ensure reliable results.Method: Several mathematical models of PV systems under shading conditions were analyzed to synthetize the characteristics, advantages and drawbacks of each one of them. Three main categories have been identified: analytical, simulation and experimental methods. Analytical and simulation methods require a basic PV model and mathematical analysis supported by computational tools; while experimental methods are based in data or measurements.Results: From the analysis of the published solutions, three representative modeling techniques with different characteristics were selected to perform a practical comparison. Those techniques were implemented and contrasted in realistic scenarios to identify the effects of the compromise between accuracy, calculation speed and PV model complexity.Conclusions: To select a mathematical model it must be taken into account the connection scheme, model of the PV unit, model of the bypass and blocking diodes, size of the system, programming complexity and simulation time. This paper provides some guidelines to choose the right model for a particular application depending on those characteristics.  Contexto: La energía producida por un sistema fotovoltaico (PV) operando en condiciones de sombreado parcial depende de las conexiones entre sus módulos y del perfil de sombra. En la literatura existen reportados múltiples modelos matemáticos en este tópico, los cuales presentan diferentes compromisos entre precisión, velocidad de cálculo y complejidad. No obstante, no es evidente como seleccionar uno de esos modelos para obtener resultados confiables en una aplicación particular.Método: Se analizaron múltiples modelos matemáticos de sistemas PV operando en condiciones de sombreado para sintetizar sus características, ventajas y desventajas. De ese análisis se detectaron tres categorías principales: métodos analíticos, de simulación y experimentales. Los métodos analíticos y de simulación requieren un modelo básico PV y análisis matemáticos soportados por herramientas de cómputo; en contraste los métodos experimentales se basan en datos y mediciones.Resultados: A partir de los análisis de los modelos reportados, se seleccionaron tres técnicas de modelado representativas para realizar una comparación práctica. Esas técnicas se implementaron y contrastaron en escenarios realistas para identificar los efectos del compromiso entre precision, velocidad de cálculo y complejidad del modelo PV.Conclusiones: Para seleccionar un modelo matemático se deben tener en cuenta el esquema de conexión, el modelo de la unidad PV, el modelo de los diodos de bloqueo y puente, el tamaño del sistema, la complejidad de programación y el tiempo de simulación. Este artículo provee algunas guías para seleccionar el modelo adecuado para una aplicación en particular dependiendo de esas características.

Convertidores de potencia para microrredes y sistemas de generación distribuidos

This paper presents an overview and critical discussion about the utilization of power converters in several microgrid configurations that incorporate non-conventional renewable energy sources and energy storage. The methodology is developed over 69 works published in this research topic. The papers are selected from databases in electrical engineering, e.g., IEEExplore, ScienceDirect, Springer, MDPI, etc. Then, the papers are classified depending on its focus, i.e., power converters in microgrids or power converters in distribution systems. At least, three classifications are proposed and one of them is made over more than 40 papers about power converters used in microgrids and electric distribution systems. Given the wide variety of microgrids and their configurations, the selection of appropriate power converters for every scenario is not trivial; therefore, this work also classifies the converters in their most common application, their advantages and disadvantages, and also point out the study domain, i.e., simulation or physical implementation. One of the main conclusions made from the overview is a gap identified in the study of direct current/ direct current microgrids despite being the simplest configuration among the three analyzed configurations. This is because hybrid and alternate current microgrids are more widely used since they allow taking advantage of the infrastructure of the current electrical systems.Este artículo presenta una visión general y una discusión crítica sobre la utilización de convertidores de potencia en varias configuraciones de microrredes que incorporan fuentes de energía renovable no convencionales y almacenamiento de energía. La metodología se desarrolla sobre 69 trabajos publicados en este tema de investigación. Los documentos se seleccionan de bases de datos en ingeniería eléctrica, p. ej. IEEExplore, ScienceDirect, Springer, MDPI, etc. Luego, los artículos se clasifican según su enfoque, es decir, convertidores de potencia en microrredes o convertidores de potencia en sistemas de distribución. Se proponen al menos tres clasificaciones y una de ellas se realiza sobre más de 40 artículos sobre convertidores de potencia utilizados en microrredes y sistemas de distribución eléctrica. Dada la gran variedad de microrredes y sus configuraciones, la selección de convertidores de potencia apropiados para cada escenario no es trivial; por lo tanto, este trabajo también clasifica a los convertidores en su aplicación más común, sus ventajas y desventajas, y también señala el dominio de estudio, es decir, simulación o implementación física. Una de las principales conclusiones extraídas de la visión general es una brecha identificada en el estudio de las microrredes de corriente continua / corriente continua a pesar de ser la configuración más simple entre las tres configuraciones analizadas. Esto se debe a que las microrredes híbridas y de corriente alterna son las más utilizadas ya que permiten aprovechar la infraestructura de los sistemas eléctricos actuales

Technical-economic feasibility analysis of micro grids integrating fuel cells in non-interconnected zones in Colombia

La necesidad de proveer soluciones energéticas sostenibles para las zonas no interconectadas de Colombia, dependiendo de los recursos renovables disponibles en cada zona, supone un desafío respecto al análisis de viabilidad técnico-económica de las alternativas de solución a través de las microrredes. Este documento tiene como objetivo analizar el impacto técnico-económico de introducir celdas de combustible en la reducción de costos a lo largo del tiempo de vida de una microrred para zonas no interconectadas, empleando el software HOMER. Dicho impacto se evalúa tanto en el diseño técnico de la microrred como en el Valor Presente Neto y en el Costo nivelado de Energía ($/kWh). El análisis se realiza a partir de la cuantificación de la demanda de un poblado prototipo, el dimensionamiento y costo de las tecnologías que conforman la microrred para atender la demanda, y la disponibilidad de los recursos renovables solar y eólico de dos zonas localizadas en diferentes latitudes no interconectadas de Colombia. Adicionalmente, se analiza el efecto de introducir las celdas de combustible en el mix energético, resaltando las ventajas obtenidas al comparar cada caso frente a una generación tradicional basada en consumo de Diésel.The sustainable power solutions provided to non-interconnected zones should be based on the renewable energy resources available in each area. This presents a challenge for the techno-economic feasibility of alternative solutions through micro grids. The objective of this work is to analyze, using HOMER software, the techno-economic impact of introducing fuel cells on cost reduction during the lifetime of micro grids in non-interconnected zones. Such impact is evaluated in the technical design of the micro grid as Present Value and Levelized Cost of Electricity ($/kWh). The analysis considers the calculation of the demand of a generic village, the size and cost of the technologies that constitute the micro grid to satisfy the demand, and the availability of solar and wind power in two areas located at different latitudes in Colombia. In addition, the effect of introducing fuel cells into the energy mix was examined. Finally, the advantages were highlighted by comparing each case with traditional generation alternatives based on diesel consumption