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Your search keyword '"Neves, Francisco A. S."' showing total 97 results
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97 results on '"Neves, Francisco A. S."'

18. Complex nk + m Repetitive Controller Applied to Space Vectors: Advantages and Stability Analysis.

Author

Neto, Rafael C., Neves, Francisco A. S., and de Souza, Helber E. P.

Subjects
*VECTOR spaces, *ELECTRIC power filters, *POWER electronics, *HARMONIC analysis (Mathematics), *STABILITY criterion, *REACTIVE power
Abstract

Repetitive controllers represent an attractive solution for systems having periodic reference or disturbance signals with high harmonic content. In order to obtain some performance improvements for three-phase plants, as grid-connected converters, complex repetitive controllers were proposed later in literature. In this article, the advantages of complex repetitive control systems over the real ones are analyzed. In addition, sufficient conditions for the input–output stability of complex repetitive control systems and modified complex repetitive control systems are obtained from the small gain theorem. These stability conditions are then used to derive the stability domains for complex repetitive control systems. Further, a relative stability analysis based on the sensitivity function is introduced. An experimental application based on an active power filter is used to exemplify the effectiveness of the proposed stability analysis. [ABSTRACT FROM AUTHOR]

Published
2021
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20. Revisão e comparação dos recentes requisitos de integração de fontes renováveis de energia.

Author

Gallego Landera, Yandi A., Neves, Francisco A. S., Neto, Rafael C., Benítez Alonso, Alejandro A., and León Viltre, Lesyani

Abstract

The growth of renewable energy generation and its integration to the electrical grid began to affect the safety and stability of the electrical system. Therefore, as renewable energy sources, such as wind and solar photovoltaic, slowly began to replace conventional plants, grid integration requirements became one of the main concerns of the researchers. As consequence, new technical requirements have been established to ensure the stability of the electrical system. In this scenario, this paper performs a review of the current requirements for the integration of renewable power plants to the electrical grid. The review is carried out by comparing the main requirements related to voltage stability, frequency stability, power quality, and active and reactive power regulations in relation to grid stability. The present study indicates that, although current integration requirements may improve stability, further improvements are still needed. [ABSTRACT FROM AUTHOR]

Published
2020

29. The SVFT-Based Control

Author

Neves, Francisco A. S., primary, Arcanjo, Maherbson A. C., additional, Azevedo, Gustavo M. S., additional, de Souza, Helber E. P., additional, and Viltre, Lesyani T. Leon, additional

Published
2014
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49. FPGA design methodology for DSP industrial applications - A case study of a three-phase positive-sequence detector.

Author

Nascimento, Paulo S.B., Neves, Francisco A. S., de Souza, Helder E. P., and Domingues, Marco A. O.

Abstract

Very important fields for utilization of FPGA technology are industrial applications such as power converters, renewable energy systems, uninterruptible power supplies, active power filters, dynamic voltage restorers and power systems protection. Many of these applications require the detection of three-phase signals characteristics. Generally, these techniques are implemented in DSP devices, with the execution time limited by sample rates of input signals. FPGA implementation results in several advantages. In this paper, an FPGA design flow for industrial digital signal processing is proposed. The first contribution is a metric for comparison between FPGA devices and DSP devices. This metric estimates the quality of implementations based on the efficiency of resources utilization in both technologies. A case study of a magnitude and phase angle detector of the fundamental-frequency positive-sequence component of a three-phase signal is presented. As a second contribution, a proposed FPGA-controller architecture is presented. For validation of the proposed metric, the advantages and possibilities of the use of FPGA in the case study are demonstrated in comparison with the DSP, in terms of the efficiency of resource usage metric, which is based on the capacity for increasing the application algorithms complexity and capacity of exploring the parallelism of operations, allowing for a much shorter execution time. [ABSTRACT FROM PUBLISHER]

Published
2012
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50. FPGA Implementation of the Generalized Delayed Signal Cancelation—Phase Locked Loop Method for Detecting Harmonic Sequence Components in Three-Phase Signals.

Author

Nascimento, Paulo S. B., de Souza, Helber E. P., Neves, Francisco A. S., and Limongi, Leonardo R.

Subjects
FIELD programmable gate arrays, PHASE-locked loops, DIGITAL electronics equipment, DIGITAL signal processing, UNINTERRUPTIBLE power supply, ALGORITHMS
Abstract

Fundamental-frequency and harmonic positive- and negative-sequence components detection is an important task for implementing power converters for renewable energy systems, uninterruptible power supplies, active power filters, dynamic voltage restorers, and also for power systems protection relays. Detection techniques of this kind are generally implemented in digital signal processor (DSP) with the execution time limited by the sampling period. The computational effort of the control algorithm can considerably increase the execution time, due to the sequential nature of processing in DSP. A promising technique for sequence components separation of three-phase signals is the so called the generalized delayed signal cancelation—phase locked loop (GDSC-PLL). Field programmable gate array's (FPGA's) capacity of exploring the parallelism of operations present in the GDSC-PLL is demonstrated in this paper through the mapping of this technique directly in hardware, allowing for a much shorter execution time than in DSP. The proposed architecture is presented, and the efficient detection of the fundamental-frequency positive-sequence with FPGA is demonstrated, with the obtained results compared with a traditional DSP implementation. In particular, the advantages and possibilities of the use of FPGA are demonstrated in comparison with the DSP. For this comparison, a metric for evaluating the capacity of complexity increase in application algorithms is proposed. [ABSTRACT FROM PUBLISHER]

Published
2013
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