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A single-phase distributed generation system (DGS) is proposed for residential power generation. It is based on an utility-interactive asymmetrical cascaded multilevel inverter with 19 levels, which is supplied by asynchronous voltage sources. It is possible to operate continuously the proposed DGS during the grid-connected or the stand-alone modes. Details about its operation modes are presented. A prototype has been implemented on a fixed-point DSP TMS320F2812. An injection of only active power into the grid utility and an uninterrupted load supply have been pursued. Simulation and experimental results presents the performance of the proposed DGS operating under normal and abnormal conditions.

Este trabalho apresenta uma metodologia para a obtenção do circuito equivalente de um motor monofásico assíncrono com capacitor de partida e capacitor permanente para simulação dinâmica. Com a utilização do circuito equivalente, se busca obter uma tensão no enrolamento auxiliar mais próxima da medida experimentalmente, onde, ao invés da utilização da relação de espiras convencional, dada pela razão do número de espiras dos enrolamentos principal e auxiliar, é utilizada a relação de espiras equivalente do motor, dada pela relação entre as reatâncias dos enrolamentos principal e auxiliar. Se busca manter a precisão da tensão obtida no enrolamento auxiliar durante a partida e em regime permanente. Por fim, a partir dos resultados obtidos e pela análise teórica do circuito, se tem como objetivo obter informações para a lógica a ser implementada em um circuito para o chaveamento do capacitor de partida.

This work studies the use of single-phase high power factor PWM rectifiers in aircrafts with variable frequency (360 to 800 Hz) power generation. It also presents design guidelines for input and output filters, and discusses the modeling and design of the voltage and current controllers. A 1 kW system is simulated considering a variable frequency grid, verifying the compliance with the aircraft power quality standards. Experimental results from a prototype allows to verify the design procedures.

Diversas publicações têm abordado a questão das distorções na faixa entre 2 a 150 kHz devido à presença cada vez maior de conversores eletrônicos de potência e soluções similares em redes elétricas de distribuição. Este artigo apresenta um breve levantamento bibliográfico objetivando a disseminação de conhecimento junto a pesquisadores e concessionárias acerca de temas relacionados às "supraharmônicas".

Este artigo apresenta o Projeto "Pesquisas Interdisciplinares em Redes Elétrica Inteligentes", o qual visa a realização de pesquisas avançadas na área de redes inteligentes de eletricidade, com foco em redes de distribuição. Trata-se de tema de grande atualidade e importâncias econômica, tecnológica, ambiental e social, com intrínseca característica interdisciplinar. A efetiva realização de uma rede inteligente de energia elétrica depende da forte interação entre pesquisas na área de sistemas de potência, fontes alternativas de energia, eletrônica de potência, sistemas de controle em rede, otimização, redes de comunicação e informação. Descreve-se o ambiente laboratorial, formado pela Microrrede LabREI e demais equipamentos, os quais permitem realizar verificações experimentais que sucedem estudos teóricos e computacionais e antecedem aplicações de campo. Ao fim, apresentam-se algumas das atividades iniciais do projeto, focadas na capacitação de recursos humanos especializados.

Neste artigo, discute-se os principais objetivos e desafios do projeto de pesquisa e desenvolvimento (projeto P&D) chamado MERGE - Microgrids for Efficient, Reliable and Greener Energy. Durante o projeto MERGE, quatro microrredes com características e finalidades diferentes serão planejadas, implementadas e testadas, tanto no modo conectado à rede como no modo isolado: uma microrrede ao nível laboratorial que terá lugar no Laboratório de Pesquisas em Redes Elétricas Inteligentes – LabREI da UNICAMP, uma microrrede de alguns prédios do campus da UNICAMP, uma nanorrede DC com pontos de carregamento de veículos elétricos, e uma microrrede residencial fora da universidade. O projeto MERGE é um esforço multidisciplinar que combina pesquisa e engenharia aplicadas aos seguintes tópicos: dimensionamento, projeto e especificação das microrredes, sistemas de gerenciamento energético, eletrônica de potência, estimação de estado, previsão de demanda/geração renovável, estabilidade, segurança cibernética e regulação brasileira. No final, as microrredes do projeto MERGE serão as primeiras do seu tipo e tamanho no Brasil, gerando oportunidades para novos modelos de negócio, e eletricidade mais sustentável, flexível e confinável aos usuários finais.

This paper reports several measurements performed at four installations sites of photovoltaic (PV) systems with a varying number of inverters (ranging from 1 to 5) and with a varying nominal power (ranging from 15 kW to 275 kW). The main aim is to observe non-intentional conducted emissions in the so-called “supraharmonics” frequency range (2 to 150 kHz). Besides confirming the presence of supraharmonics and the resulting voltage distortion, it was observed a 10-s periodic variation of magnitude of a 20-kHz distortion induced by a 4inverter 53.2-kW PV system. A simplified model is proposed and simulated to analyze and verify this phenomenon, and it is shown that small differences between the switching frequency of PV inverters due to their commutation are the most probable cause of this effect.

In this paper, MIMO space state models that represent the voltage influence in the SRF-PLL over its frequency estimations is obtained. Throughout the model development, two estimation alternatives were explored. The model accuracy was verified by simulations of the linear models and then compared with the nonlinear models. The SRF-PLL linear model represents well the behavior under single and three phase voltage sags.

This paper approaches an analysis maximum torque control distribution of an electric vehicle for induction machine with traction on the two front wheels. The comparison is based on control strategies between scalar control and direct torque control with space vector modulation (DTC-SVM) during decelerations.The strategies focus on critical braking where the combination of regenerative and mechanical braking is necessary to obtain a short distance and recovered energy. The work is simulated on Simulink/Matlab.

This paper analyses the use of PWM rectifier in variable frequency, three-phase, four-wire AC system as present in modern airplanes. The converter is analysed in terms of reliability for maintaining the correct operation of the symmetrical high-voltage DC bus and the power distribution among the phases of the AC source in case of fault. The paper discusses the standards for voltage and current quality and testing in aircraft environment. The PWM three-phase four-wire rectifier with double DC outputs is considered. Based on simulation, the topology is analysed regarding the stress on the circuits and the impact on the AC grid. It is shown the necessity of maintaining balanced DC load during the normal operation and also under fault in order to help preserving the AC power quality.

Nowadays, power electronics inverters are everywhere, from customer electronics to industry applications. In the heart of these converters there are discrete semiconductor switches. Most applications make use of Insulated Gate Bipolar Transistors (IGBTs), which are a first choice due to their switching capabilities (from several thousands of hertz to some tens of kilohertz’s) and power (from some tens of watts to megawatts). However, some applications may require faster switching frequencies, such as aeronautical and automotive electrical systems. In this scenario, FET-Based devices are a suitable choice due to their extremely fast switching characteristics. Yet, high speed switching creates problematic effects such as voltage and current oscillations which are disparately addressed in literature. Thus, this work incorporates various design advice to elaborate a methodology for the design of a 5kVA - 100kHz FET-Based full-bridge inverter. Recommendations are given for components selection, gate driver realization and layout of the power tracks. Simulations and experimental results are shown to validate the proposed methodology.

One application of the permanent magnetic motor is in the field of electric vehicles. The electric-powered wheelchair is one of its example.This paper will present a model, a simulation and analysis of a differential controlled electric-powered wheelchair using brushless DC motors. Bringing the theory of the electronics, mechanics and kinematcs, and the steps to simulate the wheelchair, including the driving and passive caster wheels. This article analyses the trajectory of the wheelchair in distinct situations as different slip surfaces, friction coefficient and gravity center over the wheelchair.

A SRF-PLL model considering voltage influences is used to develop a state-space model of a current source converter operating on droop mode. The linear and non-linear models are simulated with two different frequency estimations. Due to the frequency estimation, an instability arises in the non-linear simulation and it is verified in the linear model. Comparisons are made between the linear and non-linear models.

The More Electric Aircraft (MEA) concept focuses on the replacement of pneumatic and hydraulic actuators by electromechanical actuators and increases the electric power demand in the aircraft. This article aims to the study and the implementation of a Power Electronic Conditioner (PEC) to mitigate the unwanted effects found in the dc aircraft internal feeders. The PEC must deal with the current unbalance between the positive and negative poles of the dc bus to comply with the standards. A mathematical dynamic model and control of PEC were simulated in the software PSIM®.

This paper presents some of the experimental activities of the Power Electronics discipline of the School of Electrical and Computer Engineering of the University of Campinas, in Brazil. Simulation is a powerful tool to help the analysis of real circuits since the simulation and experimental results have a strong correlation. The course proposes seven experimental setups, covering the four basic converters: ACDC, AC-AC, DC-DC and DC-AC. Together with the topologies analysis, typical applications are explored: DC and AC motor speed control, temperature control, UPS, etc. This scenario implies a close collaboration among other disciplines, as control, analog electronics, electric machines, etc. Two of the experiments are discussed to shown the basis of the course, integrating simulation and practical circuits and applications.

This work presents an alternative method to simulate an Utility Interface (UI) consisting of a Power Electronics Converter (PEC). The proposed method is based on an equivalent resistor-inductor-capacitor (RLC) passive network circuit that resembles the output impedance of the UI, taking into account the internal resonant control characteristics of the UI. Although a controllable voltage source may emulate an UI converter, introducing an RLC network leads to a more accurate approximation of the complete UI simulated system. Comparisons are made using the frequency response of the complete system and the RLC-network circuit, and simulations are carried out on PSIM software. Results show a satisfactory dynamic and steady-state performance with a notable reduction of the elapsed simulation time. Therefore, the RLC-network-based UI could be applicable to fasten and to simplify simulations when multiples PECs are being analyzed within a complex environment, such as a microgrid.

Made available in DSpace on 2021-06-26T06:17:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Static var Compensator (SVC) has a general topology and its operational principle allows its application with distinct compensation purposes, such as voltage regulation or load balancing. Thus, this paper presents the development of a SVC prototype that could be used to test and validate a variety of control strategies proposed for the SVC applications. These strategies may include distributed/cooperative approaches, since the designed prototype has two control units with independent metering hardware. The design of the analog signal conditioning boards developed for voltage and current measurement is also presented. Design and control methods for reactive compensation under unbalanced and/or distorted voltages or loads are described and validated using the presented prototype. (C) 2018 The Authors. Published by Elsevier Ltd. Univ Estadual Campinas, Sch Elect & Comp Engn, 400 Albert Einstein Av, Campinas, SP, Brazil Sao Paulo State Univ, Inst Sci & Technol, 511 Tres de Marco Av, Sorocaba, SP, Brazil Sao Paulo State Univ, Inst Sci & Technol, 511 Tres de Marco Av, Sorocaba, SP, Brazil CNPq: 302257/2015-2 CNPq: 487471/2012-1 FAPESP: 2014/11720-7 FAPESP: 2016/08645-9

This brief describes an astable multivibrator aimed to low voltage energy harvesting using inductive coupling and bipolar junction transistors. The topology needs a bias voltage at the bases, and we propose a circuit called starting block to generate this voltage from the supply. A proof-of-concept circuit with discrete devices was able to work with a voltage as low as 50 mV and deliver 3.3 mW from a 100 mV supply. To the authors’ knowledge, it is the energy harvesting circuit with highest power capacity. It has the additional advantage of using conventional devices, in contrast with other approaches that use special devices like junction field effect transistors and native metal–oxide-semiconductor field effect transistors (MOSFETs). The circuit also needs a smaller transformer when compared to its version using conventional MOSFETs.

Passive filters are widely used in electrical system for power quality improvements. Their first installations from 1940 s and their advantages make them an attractive and standard solution up to nowadays. However, passive filters have their filtering characteristics deteriorated due to parameter variation caused by aging or temperature. In addition, a capacitor bank for power factor correction is designed for specific loads and may not supply the right amount of reactive power when loads keep being added or changed. When these issues make the passive filter and the capacitor bank incapable to keep the system operating within acceptable level of power quality, an inconvenience arises and a solution must be provided. A common one is to replace both of them either by new elements or by active power compensators. However, replacing the passive filter and the capacitor bank may not be economically feasible, because they belong to a past investment. This paper presents a solution to overcome such inconvenience keeping the passive filter and the capacitor bank installed and unchanged. It consists of installing two shunt compensators specially designed for performing what the passive filter and the capacitor bank are incapable to do. The result is a reduced processed power in the compensators. The generation of the references is based on conservative power theory (CPT). A case study is presented to prove the compensators’ efficacy and the power quality improvement.

Made available in DSpace on 2018-11-26T16:18:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This paper presents a flexible control technique for power electronics converters, which can function as an active power filter, as a local power supply interface, or perform both functions simultaneously. Thus, it can compensate for current disturbances while simultaneously injecting active power into the electrical grid, transforming the power converter into a multifunctional device. The main objective is to use all the capacity available in the electronic power converter to maximize the benefits when it is installed in the electricity grid. This objective is achieved by using the orthogonal current decomposition of the conservative power theory. Each current component is weighted by compensation coefficients (k(i)), which are adjusted instantaneously and independently, in any percentage, by means of load conformity factors (lambda(i)), thus providing online flexibility with respect to the objectives of compensation and injection of active power. Finally, simulated and experimental results are presented to validate the effectiveness and performance of the proposed approach. Univ Tecnol Fed Parana, BR-87301006 Campo Mourao, Brazil Univ Estadual Paulista, Grp Automat & Integrated Syst, BR-18087180 Sorocaba, Brazil Univ Estadual Campinas, Dept Syst & Energy, BR-13083970 Campinas, SP, Brazil Univ Estadual Paulista, Grp Automat & Integrated Syst, BR-18087180 Sorocaba, Brazil FAPESP: 2011/15884-6 FAPESP: 2013/08545-6

This paper presents a design procedure for a digital Proportional-Resonant (PR) current controller in a Grid Connected Inverter (GCI). The procedure describes a systematic list of how to compute the proportional and resonant gains as well as the coefficients for the digital resonant path. The main contribution of the design procedure is to facilitate and to support researchers who are designing GCI with current control strategies in a digital environment. The paper also presents a frequency domain analysis of a designed digital PR controller. The fictitious w-domain is used in such analysis. A case study shows the efficacy of GCI with a digital PR current controller designed based on the proposed procedure. Later, the paper discusses that the proposed procedure is valid also for digital PR controller with multiple resonant paths.

This paper presents a balancer circuit to be used in a four wire three phase boost rectifier with split capacitor topology. The goal is to discuss the problems related to the injection of DC current on the grid when the rectifier feeds unbalanced loads. Since the converter uses four wires, it is suitable for use in UPS where the fourth wire is needed to keep fixed the neutral point. This work will analyze the converter's behavior when unbalanced loads are applied to the DC bus and how they impact on the AC line currents. A balancer circuit will be modeled and a control strategy is applied to overcome the problem.

This paper describes the use of a hybrid energy storage system composed of battery and supercapacitor as power sources and a multi-input bi-directional interleaved DC/DC converter to provide energy to an electric urban bus. Using a control strategy that divides in different cutoff frequencies for each power source, it is possible to use the supercapacitor for rapid changes on the load demands, while the battery is used for the constant load.

Made available in DSpace on 2018-12-11T17:35:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-10-01 This study discusses a centralized and coordinated control of distributed multifunctional inverters connected to an electric grid. The multifunctional operation is based on the conservative power theory, which makes it possible to identify undesired current components that can be compensated. The inverters that make up the microgrid are managed through a transmission control protocol/internet protocol (TCP/IP) communication network, allowing commands from a control center, while also allowing monitoring and gauging of electrical quantities of interest related to each of the inverters. Using the control center, it is possible to adjust the current necessary for compensation, which can be shared among inverters in a coordinated manner and according to their nominal capacities. Adjustments are made by sending references to certain indexes for desired power quality at the coupling point of each inverter. Experiment results explore some compensation alternatives, employing communication flexibility among the devices that comprise the microgrid. Institute of Science and Technology Sao Paulo State University (UNESP) Federal University of Technology-Parana School of Electrical and Computer Engineering University of Campinas Institute of Science and Technology Sao Paulo State University (UNESP)

Made available in DSpace on 2018-11-29T20:09:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-07-10 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This study presents a synergistic operation between a battery energy storage (BES) and a photovoltaic generator (PVG) system to assist management of microgrids. The BES and the PVG work synergistically in a virtual single agent. The single agent consists of a group containing the BES, the PVG, and the loads in a feeder. The single agent results in a virtual distributed energy resource, capable to obey orders imposed by the supervisory controller (SC). The loads within the single agent seem not existent anymore to the SC, but they kept fed all the time. This is convenient to the microgrid in terms of management because the SC interacts with only one element and not more with all elements within the single agent. The synergistic operation arises when the SC demands orders to the single agent. To make the single agent obey the SC, the BES and PVG need to decide their operation mode, working synergistically for each other. The conservative power theory is applied to quantify active power, reactive energy, and harmonic currents in points of interest along the microgrid. The efficacy of the synergistic operation is verified through experimental results. Univ Fed Santa Catarina, Dept Engn, Rua Pomerode 710, BR-89065300 Blumenau, SC, Brazil Sao Paulo State Univ, Inst Sci & Technol, Ave Tres Marco 511, BR-18087180 Sorocaba, SP, Brazil Univ Estadual Campinas, Sch Elect & Comp Engn, Ave Albert Einstein 400, BR-13083852 Campinas, SP, Brazil Colorado Sch Mines, Dept Elect Engn & Comp Sci, 1610 Illinois St,8400, Golden, CO 80401 USA Sao Paulo State Univ, Inst Sci & Technol, Ave Tres Marco 511, BR-18087180 Sorocaba, SP, Brazil FAPESP: 2012/23914-5 FAPESP: 2017/22629-9 FAPESP: 2016/08645-9 CNPq: 421281/2016-2 CNPq: 302257/2015-2

Anti-lock brake system (ABS) control is an important solution in a vehicle to act on cracks conditions, road bumps, and different surfaces to improve driver safety. Currently, several efficient strategies on control module are being enhanced to work with braking stability. This paper studies, based on the Simulink/Matlab, the braking control for maintaining a smooth torque to shortstops, mechanical ABS and on the cooperative regenerative and mechanical braking control system for electric vehicles (EV). These are fitted with supercapacitors to achieve a high-performance braking and energy storage.

Microgrid is some part of the electric grid that may disconnect and operate autonomously, therefore it is becoming a broadly discussed theme in the ecosystem of the distribution domain. In this context, distributed generation and distributed storage may function cooperatively towards balancing energy supply and demand, as well as managing system stability and power quality. Power electronics play a very special role in this evolution since several loads are turning to be powered by some sort of electronic circuitry. In this decentralized scenario, system reliability and stability turn to be very important subjects. The interconnection stability of inverters can be addressed via its input impedance characteristics, which can be shaped to be in equilibrium with the grid. This work explores a scenario where a microgrid first operates stably when connected to the main grid. However, when islanded, the system becomes oscillatory and stability is degraded. Finally, by means of simple controller adjustment obtained throughout impedance analysis, the microgrid stabilizes.