Diogo Salles

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Papers by Diogo Salles

Information extraction from PQ disturbances — An emerging direction of power quality research

2012 IEEE 15th International Conference on Harmonics and Quality of Power, 2012

Dynamic modeling of inverter-based distributed generators with voltage positive feedback anti-islanding protection

2010 IREP Symposium Bulk Power System Dynamics and Control - VIII (IREP), 2010

This paper presents three models for dynamic analysis of inverter-based distributed generators eq... more This paper presents three models for dynamic analysis of inverter-based distributed generators equipped with voltage positive-feedback anti-islanding protection. The models analyzed are: the switched model, where the switches are represented in details, the average model, where the switches and signal generators are replaced by controlled voltage sources, and the small-signal model, where the average model is linearized. This small-signal model

Investigation of the islanding detection of induction generators

2009 IEEE Power & Energy Society General Meeting, 2009

This paper provides an analysis of the performance of the under/over frequency and under/over vol... more This paper provides an analysis of the performance of the under/over frequency and under/over voltage relays for islanding detection of squirrel-cage induction generators. This analysis is based on the nondetection zones, which are determined by extensive dynamic simulations using PSCAD/EMTDC. The presented nondetection zones are constructed considering different reactive power compensation and different detection times. Analysis on the nondetection zones

A Practical Method for Estimation of Fault Ride-Through Capability of Wind Power Farms Based on Squirrel-Cage Rotor Induction Generators

by Diogo Salles and Carlos Murari

2007 IEEE Canada Electrical Power Conference, 2007

approach is based on the steady-state equivalent circuit of the Abstract-This paper presents a pr... more approach is based on the steady-state equivalent circuit of the Abstract-This paper presents a practical method for induction generator and on the concepts of stable and unstable estimation of fault ride-through capability of wind power farms electrical-mechanical equilibrium points represented in the composed by squirrel-cage rotor induction generators. The electrical and mechanical torque versus rotor speed space [4].

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Analysis of the Impact of Induction Generators on Distribution Systems Voltage Sags Due to Unbalanced Faults

by Diogo Salles and Carlos Murari

2007 Large Engineering Systems Conference on Power Engineering, 2007

This paper presents an analysis of the impact of induction generators on voltage sag in distribut... more This paper presents an analysis of the impact of induction generators on voltage sag in distribution systems caused by unbalanced faults. It was analyzed single line-toground faults (SLGF´s) and line-to-line faults (LLF´s). The analysis is conducted through electromagnetic transient simulations. Moreover, the impact of different connections of the transformer between the generator and the power system was also investigated. The results show that the voltage sags in different system buses are affected due to the presence of induction generators.

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Characteristics of voltage relays for embedded synchronous generators protection

IET Generation, Transmission & Distribution, 2007

Here, a comprehensive characterisation of the performance of voltage relays, focusing on their ca... more Here, a comprehensive characterisation of the performance of voltage relays, focusing on their capability to detect islanding of embedded synchronous generators is presented. Such characterisation is done by using the performance curves and the concept of critical reactive power imbalance, which allows a systematic analysis of voltage relays considering a wide range of system operating points. The impacts of important factors on the relay performance are evaluated, such as the presence of voltage-dependent loads and the generator exciter control mode. Moreover, a graphical approach that allows protection engineers to adjust voltage relays to reach two objectives simultaneously: (i) to be sensitive enough to detect islanding efficiently and (ii) to satisfy the protection requirements against abnormal voltage variation is proposed. Results can be quite attractive to understand voltage relays behaviour and limitations and thus, they can be adjusted more efficiently.

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Method to Assess the Power-Quality Impact of Plug-in Electric Vehicles

IEEE Transactions on Power Delivery, 2000

ABSTRACT This paper presents a probabilistic harmonic simulation method to study the power-qualit... more ABSTRACT This paper presents a probabilistic harmonic simulation method to study the power-quality impact of electric vehicles (EVs). The proposed method takes into account the random operating characteristics of the vehicles, such as random charging time, charging duration, and vehicle locations. A multiphase model of the primary and secondary systems is used to represent the study system. Extensive case studies have been conducted using the method and the measured EV data. The results reveal that the current versions of plug-in hybrid EVs have no significant harmonic impact on power systems. However, the Level 1 charger can increase the neutral-to-earth voltage at homes which could lead to increased stray voltage incidents.

Nondetection Index of Anti-Islanding Passive Protection of Synchronous Distributed Generators

IEEE Transactions on Power Delivery, 2000

Synchronous distributed generators are prone to operate islanded after contingencies, which is us... more Synchronous distributed generators are prone to operate islanded after contingencies, which is usually not allowed due to safety and power-quality issues. Thus, there are several anti-islanding techniques; however, most of them present technical limitations so that they are likely to fail in certain situations. Therefore, it is important to quantify and determine whether the scheme under study is adequate or

Power imbalance application region method for distributed synchronous generator anti-islanding protection design and evaluation

Electric Power Systems Research, 2011

This paper presents a novel graphical approach to adjust and evaluate frequency-based relays empl... more This paper presents a novel graphical approach to adjust and evaluate frequency-based relays employed in anti-islanding protection schemes of distributed synchronous generators, in order to meet the antiislanding and abnormal frequency variation requirements, simultaneously. The proposed method defines a region in the power mismatch space, inside which the relay non-detection zone should be located, if the above-mentioned requirements must be met. Such region is called power imbalance application region. Results show that this method can help protection engineers to adjust frequency-based relays to improve the anti-islanding capability and to minimize false operation occurrences, keeping the abnormal frequency variation utility requirements satisfied. Moreover, the proposed method can be employed to coordinate different types of frequency-based relays, aiming at improving overall performance of the distributed generator frequency protection scheme.

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Large-scale control of domestic refrigerators for demand peak reduction in distribution systems

by Diogo Salles and Márcio Alcântara

Electric Power Systems Research, 2013

ABSTRACT This paper presents a practical strategy for large-scale control of domestic refrigerato... more ABSTRACT This paper presents a practical strategy for large-scale control of domestic refrigerators for demand peak reduction in distribution systems. Due to thermodynamics particularities, the refrigerators can be flexibly disconnected from the network for short periods without impacting negatively on their delivered services. Besides, combined with the fact that these loads are present in almost every residential home, the potential for energy consumption reduction is considerable. In this context, the objective of this work is threefold: develop an adequate model for simulation of individual and group of refrigerators; implement practical strategies to manage the demand of refrigerators during peak time; and analyze the impact of such strategies in the operation of distribution systems. The simulation results confirmed that the proposed strategy can contribute not only for reducing peak demand, but also for improving losses and voltage profile of power distribution systems.

Um método prático para a definição dos ajustes de relés baseados em medidas de freqüência usados para detecção de ilhamento de geração distribuída

by André Luiz Morelato França and Diogo Salles

Sba: Controle & Automação Sociedade Brasileira de Automatica, 2008

Antes de se proceder com a instalação de geração distribuída em redes de distribuição de energia ... more Antes de se proceder com a instalação de geração distribuída em redes de distribuição de energia elétrica, engenheiros de proteção devem projetar e parametrizar sistemas de proteção de forma eficiente para desconectar os geradores distribuídos dentro de um tempo pré-determinado, no caso de ocorrência de situações de ilhamento. Tanto o projeto quanto a avaliação de sistemas de proteção anti-ilhamento confiáveis exigem um estudo detalhado envolvendo numerosas simulações dinâmicas, as quais podem demandar muito tempo por parte dos especialistas de proteção. Este artigo tem por objetivo propor um conjunto de fórmulas para reduzir esse número de simulações dinâmicas. Tais fórmulas são capazes de determinar diretamente o comportamento dinâmico dos dispositivos anti-ilhamento mais empregados em geradores síncronos distribuídos: os relés baseados em medidas de freqüência. Elas Artigo submetido em 31/07/2006 1a. Revisão em 11/10/2006 2a. Revisão em 16/05/2007 3a. Revisão em 24/01/2008 Aceito sob recomendação do Editor Associado Prof. Denis Vinicius Coury são obtidas da solução analítica da equação de oscilação da máquina síncrona, juntamente com a solução das equações dos relés. Além disso, as curvas que relacionam o tempo de detecção com o desbalanço de potência ativa, conhecidas como curvas de desempenho, são empregadas para avaliar a exatidão das fórmulas. Tais curvas são obtidas tanto por simulação dinâmica quanto pelas fórmulas propostas, assim uma comparação abrangente pode ser realizada. Os dispositivos de proteção contra ilhamentos analisados neste trabalho são o relé de sub/sobre freqüência, o relé de taxa de variação de freqüência (em inglês, ROCOF relay -Rate Of Change Of Frequency relay) e o relé de deslocamento de fase ou "salto de vetor" (em inglês Vector Surge, Vector Shift ou Voltage Jump relay). PALAVRAS-CHAVE: geração distribuída, detecção de ilhamento, máquinas síncronas, proteção.

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Diogo Salles

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