Fernando Cardoso Melo

Performance Analysis of the Computational Implementation of a Simplified PV Model and MPPT Algorithm

In many research centers around the world, had been researched models that accurately represent the PV modules operation. In this context, this paper presents a modeling of photovoltaic modules, which aims to simplify the simulation of photovoltaic systems in MATLAB®/Simulink. The model in question has not been very explored in the literature and, therefore, this paper has the purpose of evaluating its results connecting the model to a boost converter, being its main function the Maximum Power Point Tracking applying one of the most known methods, the P&O (Perturb & Observe). Furthermore, this converter elevates the voltage generated by the photovoltaic modules, in order to connect the PV array to the grid through an inverter. This paper also presents a good correlation between the theoretical and practical results from the modeling of the photovoltaic cell, and was observed a high efficiency of the implemented MPPT algorithm.

Harmonic Distortion Analysis in a Low Voltage Grid-Connected Photovoltaic System

After the approval of the Normative Resolution 482, in April 17th, 2012, ANEEL has established the general conditions for microgeneration (less than or equal to 100 kW) and minigeration (greater than 100 kW and less than or equal to 1 MW), accessing the electric power distribution systems. In addition, it is established the net metering compensation system of the electric power generated. Since then, several applications for grants for connecting PV systems to the low and medium voltage grid have been performed. In this context, this paper presents the design of a 6.58 kWp photovoltaic system in the city of Uberlândia, Minas Gerais, following the standards established by that Normative Resolution and in accordance with the CEMIG ND 5.30, which establishes the criteria for connecting new micro and mini distributed generation systems to the low-voltage grid. Design criteria and results of the assessments about harmonic distortions at the point of common coupling of the installation are presented in this work.

Novel transformeless single-stage 4-switches Buck-Boost Inverter

The development of static power converters capable of transforming DC energy obtained from alternative sources into AC has become one of the main challenges in renewable energy systems. In this context, this paper presents a novel topology of step-up/step-down single-stage DC-AC converter that works with fully controlled waveforms of output voltage and input inductor currents. It also promotes high voltage gain without using a pre-regulator circuit or a transformer, reducing the weight and size of the proposed inverter structure. Preliminary simulation analysis is presented in order to prove the effectiveness of the single-stage inverter to be applied in stand-alone photovoltaic or fuel cell systems. Experimental results are included for a 300 W prototype, as well as a full discussion concerning the DSP implementation of the proposed PWM control technique.

Design and modeling of a transformerless hybrid inverter system using a fuel cell as energy storage element for microgrids with sensitive loads

The development of static power converters capable of transforming DC energy obtained from alternative sources into AC has become one of the main challenges in renewable energy systems. In this context, this paper presents a Stand-Alone Transformerless Hybrid Single-Stage Inverter that works with fully controlled waveforms of output voltage and input inductor currents. It also promotes high voltage gain without using a pre-regulator circuit, reducing the weight and size of the inverter structure. Preliminary experimental results are presented in order to prove the effectiveness of the proposed hybrid inverter in a stand-alone photovoltaic system. An intelligent energy-management control strategy has been developed for purpose of providing conditions for saving the auxiliary power source energy through the extraction of maximum power from the PV array. As a result, an autonomous energy system has been achieved since it provides reduced dependence on weather conditions, leading to a high reliability system.

Proposal of a Photovoltaic AC-Module With a Single-Stage Transformerless Grid-Connected Boost Microinverter

Microinverters for photovoltaic (PV) modules can improve the energy generation by reducing the effects of shading, since the energy harvesting of each PV module can be controlled individually. In this context, this paper presents a topology of single-stage transformerless grid-connected boost microinverter. It promotes high voltage gain without using a preregulator circuit or a high/low-frequency transformer. A 500 W laboratory prototype was implemented and experimental tests were carried out so that the proposed microinverter was evaluated in a grid-connected PV system. Experimental analysis was performed in order to corroborate the theoretical approach and to verify the effectiveness of the proposed modified Perturb and Observe “Gama” maximum power point tracking technique and the proportional-resonant (P-Res) grid current controller under different irradiation conditions and under partial shading.

AVALIAÇÃO DE DESEMPENHO DE MODELOS COMPUTACIONAIS REPRESENTATIVOS DE PAINÉIS FOTOVOLTAICOS

Este trabalho tem como objetivo apresentar estudos investigativos correlatos a modelagem do principal elemento da geracao distribuida por fonte solar, o modulo fotovoltaico, por meio da utilizacao de programas computacionais no dominio do tempo. Serao avaliados dois modelos matematicos que representam o comportamento do modulo fotovoltaico na plataforma Matlab/Simulink, dos quais um deles e disponibilizado pela biblioteca deste software, fundamentado na modelagem tradicional, e o seguinte implementado de forma simplificada. Complementarmente ao estudo e analise computacional das distintas tecnicas de modelagens, tem-se a avaliacao de desempenho dos modelos por meio de ensaios reais em campo. Palavras-chave: Geracao Distribuida, Modelagem, Modulo Fotovoltaico, Redes Inteligentes. ABSTRACT This paper aims to present investigative studies related to modeling of the main component of solar distributed generation, the PV modules, by means of simulation software in the time domain. Two mathematical models will be evaluated that represent the behavior of the photovoltaic module in the Matlab/Simulink platform, one of them being available from the software library, based on traditional modeling, and the other one implemented by a simplified way. In addition to this study and computational analysis of different modeling techniques, the paper presents a real performance evaluation through practical results. Keywords: Distributed Generation, Modeling, Photovoltaic Module, Smart Grid.

Didactic platform for teaching of three-phase rectifier circuits in power electronics

With the aim of preventing an Electrical Engineering course from being predominantly theoretical, the didactic materials used in laboratory activities are essential to make the learning process easier and more stimulating for the student. In this context, this paper presents a didactic platform developed for teaching a.c.-d.c. converters in the subject of power electronics at the Federal University of Uberlândia (UFU), Brazil. The proposed platform consists of a three-phase controlled and/or uncontrolled rectifier. The IC TCA785 is used to control thyristor operation. In order to make teaching more dynamical, the didactic platform was designed to have various operating conditions, simulating, for example, breakdown components and mixed use of thyristors and diodes. A prototype of the proposed platform was built, evaluated experimentally in the laboratory and the results are shown in this paper.