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16th Seminar on Power Electronics and Control, SEPOC 2024

作者： De Santana Borges, Juliano Freitas, Cleiton M. Monteiro, Luis F. C. Rio de Janeiro State University Post-Graduate Prog. of Electronic Eng Rio de Janeiro Brazil Rio de Janeiro State University Post-Graduate Prog. of Electronic Eng Dept. of Electrical Engineering Rio de Janeiro Brazil

ISBN: (纸本)9798350379419

Technological advances in the field of power electronics have made direct current (DC) more viable, paving the way for the so-called DC microgrids. In microgrids, it is quite common to provide the power electronic converters with some kind of droop control to properly and automatically share the required load. With DC-DC converters, the simplest way to do that is using the concept of virtual resistance, but it does not provide any inertial response necessary to improve the voltage quality and guarantee the microgrid's stability. Alternatively, there is the concept of a virtual DC machine, which allows the load share and the desired inertial response. In this context, this paper adapts this idea in such a way that the control loops are cascaded and the similarities with the DC machine are clearer. The innermost loop controls the converter's output voltage, considering two possibilities for this part: one open-loop-based and another closed-loop-based. The cascaded outer loops implement the electromagnetic and electromechanical dynamics of the DC machine and the effect of the governor. A detailed methodology is provided for setting the machine parameters according to the desired dynamics. Simulations are carried out to compare the proposed virtual DC machine with a regular virtual-resistance-based droop approach. The results show smother dynamics for the proposed control, while maintaining the proper load share. © 2024 IEEE.

关键词： Microgrids

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Resonance Analysis on Inverter-Populated Power Grids 8

Resonance Analysis on Inverter-Populated Power Grids

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8th Southern Power Electronics Conference and the 17th Brazilian Power Electronics Conference, SPEC / COBEP 2023

作者： Freitas, Cleiton M. Monteiro, Luís F. C. Do Nascimento, Guilherme H. C. Rio de Janeiro State University Dept. of Electrical Engineering Post-Graduate Prog. of Electronic Eng. Rio de Janeiro Brazil Post-Graduate Prog. of Electronic Eng. Rio de Janeiro State University Rio de Janeiro Brazil

ISBN: (纸本)9798350321128

Inherently, power grids with multiple inverters have interactions that may lead to resonant phenomena, which is undesirable. Thus, this paper exploits the interaction between grid-following converters and the power grid. Generally, the idea is to use the representation of the electrical grid populated by converters to determine the resonant modes using a frequency- domain impedance-modeling approach and eigenvalue analysis. This knowledge will enable planners to predict the oscillatory phenomena caused by inverters and prevent them by proposing modifications to the control systems of the inverters. The paper presents a step-by-step discussion of how to organize the impedance models into a multibus power grid and how to conduct eigenvalue analysis in this aggregated model. For testing the models, it was considered a 10-bus grid in different scenarios, one stable and another unstable. Simulations were also carried out to validate the results of the analysis. © 2023 IEEE.

关键词： Grid-Following Converters Inverter-populated Grids Modal Analysis Resonance Analysis

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Nanoscale engineering of Sr-doped ZnO nanorods/CuO nanocomposites for the photocatalytic treatment of methylene blue pollutant

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Materials Chemistry and Physics 2025年 343卷

作者： Ali Tekin Raşit Aydın Ümmühan Akın Osman Kahveci Abdullah Akkaya Hüsnü Kara Bünyamin Şahin Department of Physics Faculty of Sciences Selcuk University Konya Turkey Department of Physics Faculty of Sciences Erciyes University Kayseri Turkey Mucur Technical Vocational Schools Tech. Prog. Department Kırşehir Ahi Evran University Kırşehir Turkey Department of Basic Sciences Faculty of Engineering Necmettin Erbakan University Konya Turkey Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

This study investigates the effect of Sr doping on the physical and photocatalytic properties of ZnO nanorods/CuO nanocomposites. Various techniques were applied to understand how Sr doping modifies these films. SEM analysis showed that ZnO and CuO formed structures such as nanorods or nanowires. Sr-doped samples exhibited increased aggregation compared to undoped composites, with Sr doping levels of 2.0 % and 4.0 % leading to more pronounced morphological changes. AFM measurements showed an increase in average roughness from 70.53 nm to 111.83 nm with higher Sr doping levels. XRD analysis showed that the crystallite sizes decreased from 36.20 nm for undoped samples to 31.55 nm and 29.90 nm with 2.0 % and 4.0 % Sr doping, respectively. FTIR Spectroscopy provided insights into the chemical bonding changes induced by Sr doping. The bandgap analysis revealed that Sr doping in the ZnO/CuO nanocomposites enhanced the bandgap energy, with the value increasing from 2.41 eV in the undoped sample to 3.61 eV at 4.0 % Sr doping. electrical conductivity measurements showed a decrease in total resistance values as the Sr doping ratio increased. The contact resistance values increased from 3.13 × 10 9 Ω in the un-doped samples to 3.22 × 10 8 Ω in the 4.0 % Sr-doped films. It was observed that 2.0 % Sr doping increased the photocatalytic degradation of the ZnO nanorods/CuO nanocomposite films, whereas 4.0 % Sr doping decreased this effect. Thus, the dynamic evaluation of the catalytic performance with TOF yields values of 0.176 and 0.184 for ZnO nanorods/CuO nanocomposites films and ZnO nanorods/CuO:Sr (2.0 %), respectively.

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Are folksonomies shared conceptualizations?

Are folksonomies shared conceptualizations?

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International Conference on computer Supported Cooperative Work in Design

作者： Josiane M. Pinheiro Cesar A. Tacla Emerson Cabrera Paraiso Graduate Prog. in Electrical and Computer Engineering Federal Technological University of Parana Curitiba-Pr Brazil Graduate Program in Informatics Pontificia Universidade Catolica do Parana Curitiba-Pr Brazil

This article presents a method to assess whether folksonomies are useful shared conceptualizations for conceptual modeling. A method based on the tripartite model (actors, concepts and instances) induces from social applications a folksonomy related to a domain of knowledge. The hypothesis of this paper is that if folksonomies are shared conceptualizations, then using them in conceptual modeling should reduce the number of divergences between actors when they elicit terms to be part of a model (a concept map in this article). A controlled experiment of conceptual modeling was performed with experimental groups who received tags inducted from data of categorizations from Delicious and control groups who received terms extracted from Web pages categorized on Delicious. The results show that the experimental groups obtained less divergences (on average) in elicitation of terms when compared to control groups.

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Grid-Forming MMC: A Comparison between Single- and Dual-Loop Control Approaches 16

Grid-Forming MMC: A Comparison between Single- and Dual-Loop...

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16th Brazilian Power Electronics Conference, COBEP 2021

作者： Freitas, Cleiton M. Watanabe, Edson H. Monteiro, Luis F. C. Rio de Janeiro State University Dept. of Electrical Engineering Rio de Janeiro Brazil Federal University of Rio de Janeiro Electrical Engineering Program - COPPE Rio de Janeiro Brazil Rio de Janeiro State University Post-Graduate Prog. of Electronic Eng. Rio de Janeiro Brazil

ISBN: (纸本)9781665421294

This work presents an analysis of the grid-forming Modular Multilevel Converter (MMC), in the frequency domain, when it is controlled through single or dual-loop implementation. The dual-loop approach presents an inner current-loop control gathered with the external voltage-loop control, whereas the single-loop only presents a voltage-loop control for the grid-forming capability. In both cases, the control algorithms were implanted in a natural reference frame, including resonant controllers. The paper follows an impedance-modeling approach for introducing the analytical representation of the MMC in the frequency domain. These representations are, in fact, the linearized Teéenin-equivalent models of the single- and dual-loop grid-forming MMC. The results showed that the inner current-loop control is a feasible approach for damping specific resonant peaks of the Thevenin-equivalent impedance. In other words, the current-control loop adds a resistive parcel in MMC impedance in the frequency range in which the resonant peaks appear. As a consequence, the LC resonance between this impedance and the capacitor bank in the main bus is damped. The article also contains some switching-level EMTDC/PSCAD simulations to validate the work. © 2021 IEEE.

关键词： Frequency domain analysis

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Control of DC-DC converters in DC microgrids: adaptation of virtual DC machine control

Control of DC-DC converters in DC microgrids: adaptation of ...

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Power Electronics and Control (SEPOC), Seminar on

作者： Juliano de Santana Borges Cleiton M. Freitas Luís F. C. Monteiro Post-Graduate Prog. of Electronic Eng Rio de Janeiro State University Rio de Janeiro Brazil Dept. of Electrical Engineering Post-Graduate Prog. of Electronic Eng Rio de Janeiro State University Rio de Janeiro Brazil

ISBN: (数字)9798350379419

ISBN: (纸本)9798350379426

Technological advances in the field of power electronics have made direct current (DC) more viable, paving the way for the so-called DC microgrids. In microgrids, it is quite common to provide the power electronic converters with some kind of droop control to properly and automatically share the required load. With DC-DC converters, the simplest way to do that is using the concept of virtual resistance, but it does not provide any inertial response necessary to improve the voltage quality and guarantee the microgrid’s stability. Alternatively, there is the concept of a virtual DC machine, which allows the load share and the desired inertial response. In this context, this paper adapts this idea in such a way that the control loops are cascaded and the similarities with the DC machine are clearer. The innermost loop controls the converter’s output voltage, considering two possibilities for this part: one open-loop-based and another closed-loop-based. The cascaded outer loops implement the electromagnetic and electromechanical dynamics of the DC machine and the effect of the governor. A detailed methodology is provided for setting the machine parameters according to the desired dynamics. Simulations are carried out to compare the proposed virtual DC machine with a regular virtual-resistance-based droop approach. The results show smother dynamics for the proposed control, while maintaining the proper load share.

关键词： DC machines Seminars Resistance Simulation Microgrids DC-DC power converters Power electronics Stability analysis Voltage control Load modeling

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Resonance Analysis on Inverter-Populated Power Grids

Resonance Analysis on Inverter-Populated Power Grids

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IEEE Annual Southern Power Electronics Conference (SPEC)

作者： Cleiton M. Freitas Luís F. C. Monteiro Guilherme H. C. do Nascimento Dept. of Electrical Engineering / Post-Graduate Prog. of Electronic Eng. Rio de Janeiro State University Rio de Janeiro Brazil Post-Graduate Prog. of Electronic Eng. Rio de Janeiro State University Rio de Janeiro Brazil

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Implementation of a virtual environment for interacting with a coordinate measuring machine

Implementation of a virtual environment for interacting with...

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2004 IEEE Symposium on Virtual Environments, Human-computer Interfaces and Measurement Systems, VECIMS

作者： Calonego Jr., Nivaldi Kirner, Claudio Kirner, Tereza G. Abackerli, Álvaro José Graduate Program in Computer Science Methodist University Piracicaba Rodovia Açúcar Km 156 Piracicaba SP Brazil Grad. Prog. in Indust. Engineering Methodist University of Piracicaba Rod. Sta Barbara/Iracemapolis Km. 1 13450-000 - Sta Barbara d'Oeste SP Brazil

ISBN: (纸本)0780383397

This paper focuses on implementation issues of a virtual environment to support the interaction with a Coordinate Measuring Machine (CMM), which is used to measure dimensions and form of mechanical parts. First, it gives an overview of the implementation, presenting the software "Avalon" and the basic architecture of the developed application. Then, it describes the execution environment, including the description of equipments and devices, characteristics and constraints, and system execution. Finally, it presents the conclusions of the work.

关键词： Coordinate measuring machines

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A Comparative Analysis of Voltage Control Methods for Single-Phase Grid-Forming Inverters

A Comparative Analysis of Voltage Control Methods for Single...

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On-Line Conference (ONCON), Industrial Electronics Society Annual

作者： Vitor K. Nojima Marllon X. Barroso Cleiton M. Freitas Harold D. De Mello Luís F. C. Monteiro Dept. of Electrical Engineering Rio de Janeiro State University Rio de Janeiro Brazil Dept. of Electrical Engineering / Post-Graduate Prog. of Electronic Eng. Rio de Janeiro State University Rio de Janeiro Brazil Post-Graduate Prog. of Electronic Eng. Rio de Janeiro State University Rio de Janeiro Brazil

This work compares three types of control-loop implementation for single-phase grid-forming inverters. The first two follow a single-loop approach using proportional resonant (PR) controllers in the Natural Reference Frame and proportional integral controllers in the synchronous reference (SRF-PI). The third control loop is also based on an SRF-PI controller. However, it has two loops, where the innermost one is related to the current that passes through the filter capacitor, and the outermost one is related to the inverter voltage. The article employs a simulation methodology to analyze the dynamic behavior of the control loops. In the established environments, it was shown that systems in SRF present a better transient response to step changes in the reference value. Furthermore, all three systems achieve zero error at steady state conditions.

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A simple scheme of decomposition and reconstruction of continuous-time signals by B-splines

A simple scheme of decomposition and reconstruction of conti...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： K. Ichige M. Kamada R. Ishii Doctoral Prog. in Engineering University of Tsukuba Tsukuba Japan Department of Computer Information Science Ibaraki University Hitachi Japan Division of Electrical Compu. Engineering Yokohama National University Yokohama Japan

An approximate scheme is proposed for decomposing and reconstructing a continuous-time signal as a linear combination of the B-splines. It is an oversampling discrete-time implementation derived by substituting the multifold RRS functions for the B-splines. Its analysis yields conditions for the circuit parameters to avoid instability and overflow, and to meet required precision. A design example and its numerical simulation are also presented.

关键词： Spline Convolution Numerical simulation Wavelet domain Signal generators Analog circuits Costs Hardware Semiconductor device measurement Integrated circuit measurements

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