Papers by SERGIO AUGUSTO OLIVEIRA DA SILVA
Conversor CC-CC Bidirecional Aplicado ao Controle de Carga de Baterias em um Sistema Fotovoltaico de Geração Distribuída
OBJETIVO: Desenvolver um conversor CC-CC bidirecional atuando como controlador de carga de bateri... more OBJETIVO: Desenvolver um conversor CC-CC bidirecional atuando como controlador de carga de baterias eletroquimicas em um sistema fotovoltaico de geracao distribuida. O conversor deve realizar o processo de carga das baterias de forma a nao reduzir a vida util das mesmas. Um adequado uso das baterias e importante devido ao seu vasto uso em sistemas fotovoltaicos autonomos, onde e necessario investir em baterias para realizar o armazenamento de energia na ausencia de luz solar. METODOS: A topologia em estudo e composta por um conversor CC-CC buck/boost bidirecional em corrente e baterias de chumbo-acido. Sao obtidas as funcoes de transferencia da malha de tensao e malha de corrente da etapa de carga, onde o conversor bidirecional atua como um conversor buck . Sao calculados os ganhos do controlador PI (proporcional-integral) utilizado na malha interna de corrente bem como na malha externa de tensao. A carga do banco de baterias e dividida em dois estagios, ou seja, os estagios de sobrecarga e flutuacao. RESULTADOS: Sao apresentados os graficos de tensao e corrente, assim como o estado de carga ao longo do tempo de carga das baterias. CONCLUSOES: A etapa de carga das baterias foi realizada de modo que os niveis de tensao e corrente se mantiveram dentro dos limites estabelecidos em projeto. Desta forma o processo de carga foi executado de maneira eficaz respeitando os limites de seguranca das baterias, assegurando a preservacao da vida util das mesmas.
Energies, Apr 22, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Analysis of a Multifunctional Inverter Active-Filtering Function Influence on the Small-Signal Stability of Inverter-Based Islanded AC Microgrids
IEEE Transactions on Industrial Electronics
Eletrônica de Potência
Resumo-Este trabalho apresenta uma nova topologia integrada de inversor monofásico para aplicaçõe... more Resumo-Este trabalho apresenta uma nova topologia integrada de inversor monofásico para aplicações autônomas em sistemas de geração de energia. A topologia proposta, nomeada como Inversor Integrado Zeta Monofásico (I2ZM), é projetada para fornecer uma tensão senoidal, regulada e com baixa distorção harmônica para cargas locais a partir de fontes de tensão CC, em um sistema de geração autônomo. O I2ZM é construído a partir da integração de conversores CC-CC Zeta, sendo este projetado para operar no modo de condução descontínua. Por ser uma estrutura de inversor integrado, o I2ZM apresenta vantagens como a de não precisar de um conversor de potência para realizar a elevação da tensão de entrada, ou da necessidade de possuir níveis elevados de tensão na entrada do inversor para realizar a conversão CC/CA. Neste sentido, é realizado um estudo completo do I2ZM, envolvendo análises quantitativa e qualitativa, bem como a análise de pequenos sinais. Por meio de resultados de simulação computacional e experimentais, a viabilidade e a funcionalidade do inversor I2ZM proposto são apresentadas e avaliadas.
Comparative static and dynamic analysis of single‐ and double‐stage multifunctional 3‐phase grid‐tied photovoltaic systems
IET Renewable Power Generation
Integrated Zeta Inverter Applied in a Single-Phase Grid-Connected Photovoltaic System
2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC)
This paper presents a novel integrated topology for step-up the photovoltaic array voltage, as we... more This paper presents a novel integrated topology for step-up the photovoltaic array voltage, as well as to inject all the extracted PV array energy into the single-phase AC utility grid. The topology is based on the Zeta converter, named as Zeta Inverter, and its output current is controlled using hysteresis current control. The maximum power point tracking is performed employing the perturb and observe algorithm. Besides the obtaining low total harmonic distortion in the grid-injected current, the proposed system is proposed to replace the traditional double stage photovoltaic system. This paper presents the converter operation, the control technique, and the main simulation results in order to demonstrate the feasibility of the proposed system.
IET Renewable Power Generation
This study presents an improved extremum-seeking control (ESC) method, intended to optimise the m... more This study presents an improved extremum-seeking control (ESC) method, intended to optimise the maximum power point tracking (MPPT) in a photovoltaic (PV) generation system. More specifically, to overcome the problem associated with partial shading in PV systems that leads to multiple operating points, an adaptive loop based on the measured PV array power is added to the conventional ESC. This procedure creates a variable amplitude of the perturbation signal and is able to accurately reach and track the global maximum power point (GMPP). The perturbation signal amplitude changes only when a predetermined power variation value is exceeded. As a result, this MPPT algorithm provides an efficient extraction of solar energy, avoids large oscillations in output response, and ensures the proper operation and performance of the system. The ESC theory is described in detail and the feasibility and effectiveness of the proposed approach are proved through simulation and experimental results. Furthermore, comparative tests show the proposed method's performance improvement, compared to the conventional ESC, evaluated in terms of convergence time, power oscillation in steady state, and accuracy to track the GMPP. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Influence of the PLL phase-angle quality on the static and dynamic performance of grid-connected systems
2017 Brazilian Power Electronics Conference (COBEP), 2017
This paper presents some effects that contribute to performance degradation of grid-connected sys... more This paper presents some effects that contribute to performance degradation of grid-connected systems, when they are subjected to operate under distorted reference phase-angle signals. In many power electronics applications, grid-tied systems are developed on the synchronous reference frame (SRF) and make use of the synchronous unit vector coordinates to compute their control references. Usually, the unit vector coordinates are generated from the estimation of the utility phase-angle, which is obtained by means of phase-locked loop (PLL) schemes. Thus, static and dynamic disturbances present in the utility voltage can generate distorted phase-angle signals, and, hence, can affect the quality of the synchronous unit vector coordinates. In this paper, two single-phase SRF-based PLL schemes, which operate under distorted utility voltage conditions, as well as distinct bandwidth PI controllers, are used to generate the current control references of a single-phase shunt active power filter (S-APF). Experimental results based on digital signal controller are used to evaluate the problems that can interfere on the S-APF performance.
Inversores integrados baseados no conversor Zeta em sistemas fotovoltaicos
XXVI Seminário de Iniciação Científica e Tecnológica da UTFPR, Oct 11, 2021
Modified zeta inverter intended for single-phase grid-tied photovoltaic system
Sustainable Energy Technologies and Assessments, 2022
Enhanced Space-State Reduced-Order Microgrid Model in Common DQ-Reference Frame
2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC), 2019
Inverter-based droop-controlled microgrids systems are becoming attractive solutions to meet futu... more Inverter-based droop-controlled microgrids systems are becoming attractive solutions to meet future energy demand in a sustainable way. The development of accurate models is crucial for control loops design and performance assessment of the system. However, extracting essential information about the overall microgrid behavior from complete models can be a hard task, as well as can involve a high computational burden depending on the microgrid size. Therefore, the development of a reduced-order model that properly represents the dynamic performance of the microgrid in a computationally efficient way is mandatory. In this paper, an enhanced reduced-order model able to represent the influence of network dynamics on the performance of the droop-controlled microgrid is presented. By means of simulation results the fidelity improvement of the proposed microgrid model is confirmed.
Comparative Analysis of PSO techniques applied in a Single-Phase Grid-Tied PV System
2021 Brazilian Power Electronics Conference (COBEP), 2021
Due to the nonlinearities present in the PV array characteristic curves (current versus voltage a... more Due to the nonlinearities present in the PV array characteristic curves (current versus voltage and power versus voltage), it is mandatory the use of maximum power point tracking (MPPT) to ensure the maximum PV array power has been extracted. Furthermore, when the PV array is subjected to partial shading conditions, the MPPT algorithms must deal with problems associated with global and local maximum powers. Therefore, to deal with partial shading problems, this paper presents a comparative analysis between the particle swarm optimization technique and its variations, such as PSO Classic (PSO 1), PSO Non-linear (PSO 2) and PSO Improved-Chaos (PSO 3). By simulation results the PSO techniques are evaluated to each other taking into account the time to reach the global maximum power, the extracted PV array power, as well as the power oscillation in steady-state.
Comparative Analysis of Alternatives for Virtual Impedance Representation in a Small-Signal Reduced-Order Model for Low-Voltage Islanded AC Microgrids
2021 Brazilian Power Electronics Conference (COBEP), 2021
The development of high-fidelity and computational-effective microgrid models is crucial to asses... more The development of high-fidelity and computational-effective microgrid models is crucial to assess the performance of microgrids in real-time applications. Therefore, the development of accurate reduced-order (R-O) microgrid models plays a fundamental role in the deployment of this concept. On the other hand, the virtual impedance techniques are essential for power decoupling and microgrid damping. However, the virtual impedance representation in R-O models has not been properly addressed in the literature. Hence, this paper explores two different alternatives for the virtual impedance representation in a reduced-order (R-O) microgrid model: i. the inclusion of virtual impedance inside the network model using Kron reduction; and ii. The inclusion of virtual impedance inside the grid-forming converter model. It was found that for low values of the voltage droop coefficient, both approaches provide similar results. However, as the voltage droop coefficient increases, the second alternative leads to more accurate results. Simulation and experimental results are presented in order to validate the analysis done.
Hybrid Energy Storage System Sizing for Smoothing Renewable Generation Intermittencies
2021 Brazilian Power Electronics Conference (COBEP), 2021
This paper presents a strategy for sizing the capacity of a lead-acid battery and the capacitance... more This paper presents a strategy for sizing the capacity of a lead-acid battery and the capacitance of an ultracapacitor that compose a passive hybrid energy storage system, useful for smoothing grid power steps caused by renewable generation sources. This analysis is based on the electrical model of the battery/ultracapacitor association, determining the settling time and the instantaneous power ratio absorbed by each one when subjected to current step input. Based on this study, the storage elements were dimensioned. The smoothing capability obtained by the hybrid storage system is analyzed in a DC-bus, in which the power balance can be analyzed. It is connected to the hybrid storage system, using two cascaded bidirectional buck-boost converters, to the generation source, and to the grid, where the last two are considered current sources. The theoretical development was validated, and the power balance in this DC-bus was analyzed by computational simulations.
Embedded System to Detect Bearing Faults in Line-Connected Induction Motors
2018 XIII International Conference on Electrical Machines (ICEM), 2018
Due to their prominent role in the production of electromotive force, three-phase induction motor... more Due to their prominent role in the production of electromotive force, three-phase induction motors are found in a wide variety of industrial applications. However, these motors are subject to a range of defects which can hinder them from functioning properly. Accordingly, this paper proposes the use of an artificial neural network method to detect and classify bearing faults in three-phase induction motors which are connected directly to the power grid. After embedding the proposed method in a digital signal processor, laboratory tests were conducted on the motors by employing practical conditions of unbalanced supply voltages and applying a wide range of load torque to the shaft. Analysis were performed in the time domain, based on acquiring the voltage and current amplitudes in the motor supply and by using a half-cycle of the voltage grid. For further validation of the proposed embedded system, field tests were conducted on factory where motors are used in the sugarcane ethanol industry.
Eletrônica de Potência, 2019
Resumo-Este trabalho apresenta o desenvolvimento de um emulador eólico eletrônico (EmEE), o qual ... more Resumo-Este trabalho apresenta o desenvolvimento de um emulador eólico eletrônico (EmEE), o qual envolve os modelos dinâmicos da turbina eólica, do gerador síncrono de ímã permanente e do acoplamento mecânico turbina-gerador. Tais modelos são empregados na geração das referências de tensão do EmEE, as quais são sintetizadas por um inversor de tensão trifásico a três fios, de forma que um aerogerador real possa ser emulado para diferentes velocidades do vento. O EmEE proposto apresenta como vantagens o seu baixo custo de implementação e sua versatilidade na emulação de diferentes modelos de aerogeradores comerciais, viabilizando a realização de diversas pesquisas em laboratório. Um retificador controlado trifásico é usado no estágio de entrada do EmEE para controlar a tensão do barramento CC do inversor, bem como drenar da rede elétrica correntes senoidais, de forma que uma efetiva correção do fator de potência seja alcançada. Tanto o modelo matemático do inversor quanto do retificador de entrada, são representados no referencial síncrono dq. No intuito de validar o estudo realizado, assim como avaliar os desempenhos estáticos e dinâmicos do EmEE proposto, resultados experimentais são apresentados considerando o sistema submetido a diferentes tipos de carga e perfis de vento. Palavras-chave-Emulador eólico eletrônico, Gerador síncrono, Turbina eólica.
Controladores SRF Aplicados em Condicionadores Ativos de Potência em Sistemas Trifásicos a Quatro - Fios
Este artigo apresenta analise comparativa envolvendo quatro estrategias usadas para extrair as co... more Este artigo apresenta analise comparativa envolvendo quatro estrategias usadas para extrair as correntes trifasicas de compensacao, aplicadas a um sistema UPS (Uninterruptible Power Supply), baseado no sistema de eixos de referencia sincrona (SRF). Tais estrategias tambem podem ser usadas para gerar tensoes e correntes de compensacao em outras aplicacoes de condicionamento ativo de potencia. Com o objetivo de obter as correntes de compensacao, filtros passa-baixa (FPB) convencionais dos tipos Butterworth e de media-movel (FMM) sao usados nos controladores SRF de corrente. Os FPB convencionais sao implementados usando as estrategias: Estrategia de Compensacao Monofasica e Estrategia Aperfeicoada de Compensacao Monofasica. Os FMM tambem foram implementados usando s estrategias: Estrategia de Compensacao Monofasica e Estrategia Aperfeicoada de Compensacao Monofasica. Todos os algoritmos de compensacao sao testados em sistema UPS line-interactive trifasico com condicionamento ativo de p...
Application of PSO method for maximum power point extraction in photovoltaic systems under partial shading conditions
2015 IEEE 13th Brazilian Power Electronics Conference and 1st Southern Power Electronics Conference (COBEP/SPEC), 2015
This paper presents a maximum power point tracking (MPPT) technique based on particle swarm optim... more This paper presents a maximum power point tracking (MPPT) technique based on particle swarm optimization (PSO) method, which is applied to a photovoltaic (PV) system. It is well known that photovoltaic (PV) panel present a nonlinear relationship between its current and voltage quantities. Furthermore, when PV panels are under partial shading, the characteristic curve IpvxVpv can present, simultaneously, several local and global maximum power points. Therefore, the proposed MPPT-PSO algorithm deals to overcome the partial shading effects, tracking the global maximum power point in order to maximize the power extraction of the PV arrangements. Experimental and simulation results are presented to demonstrate the effectiveness of the proposed MPPT-PSO algorithm, when it is compared with the well-known Perturb and Observe (P&O) MPPT technique.
This paper presents an application of an active compensation method, applied to a three-phase lin... more This paper presents an application of an active compensation method, applied to a three-phase line-interactive uninterruptible power supply (UPS) system with series and parallel active power line conditioning capabilities. The control strategy, employed to achieve the reference currents for the UPS system, is based on the synchronous reference frame (SRF) method. The reference currents, obtained from the SRF algorithm, are used to compensate the reactive power and to eliminate harmonic currents generated from non-linear loads. The reference currents of the SRF-based controller does not have the task of compensating fundamental zero sequence component of the neutral current, due to unbalanced loads or unbalance source voltages conditions. Thus, the efficiency of the three-phase UPS system is increased when it is feeding unbalanced single-phase non-linear loads. Besides, a mode to control the active power flow through the series and parallel active power filters of the UPS system is p...
Este trabalho apresenta um sistema UPS (Uninterruptible Power Supply) line-interactive monofasico... more Este trabalho apresenta um sistema UPS (Uninterruptible Power Supply) line-interactive monofasico, destinado a aplicacoes de baixa potencia. Dois conversores Push-Pull operando com baixa tensao no barramento CC sao utilizados para executar o condicionamento ativo de potencia serie e paralelo, tal que o conversor serie controla a corrente de entrada, enquanto o conversor paralelo controla a tensao de saida. No modo de operacao standby (rede presente), o sistema UPS opera como um condicionador unificado de qualidade de energia (UPQC- Unified Power Quality Conditioner) ao realizar a supressao de harmonicos da tensao da rede e corrente de carga, a compensacao de afundamentos e elevacoes de tensao, assim como a compensacao da potencia reativa da carga. Uma estrategia de controle simplificada e apresentada, na qual as referencias senoidais do controle da tensao da carga e corrente da rede sao obtidas por meio de um sistema de deteccao de ângulo de fase (PLL- Phase-Locked Loop) operando em...
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Papers by SERGIO AUGUSTO OLIVEIRA DA SILVA