Explanipedia

Ester-based Dielectric Fluid for Power Transformers: Design and Test Experience under the GreenEst Project Open

Salvador Carvalhosa, Hélder Leite, Mário Soares, Fábio Branco, Carlos A. Sá , et al. · 2022

Ester-based dielectric fluids have now been on the market for several decades, providing fire-safe and environmentally friendly alternatives to mineral oils, which have traditionally been used in transformers and other electrical equipment…

A Survey of Islanding Detection Methods for Microgrids and Assessment of Non-Detection Zones in Comparison with Grid Codes Open

José Antonio Cebollero, D. Cañete, Susana Martín-Arroyo, M. García-Gracia, Hélder Leite · 2022

Detection of unintentional islanding is critical in microgrids in order to guarantee personal safety and avoid equipment damage. Most islanding detection techniques are based on monitoring and detecting abnormalities in magnitudes such as …

Optimal partitioning in distributed state estimation considering a modified convergence criterion Open

Sajjad Asefi, Elena Gryazina, Hélder Leite · 2021

Distributed state estimation (DSE) is considered as a more robust and reliable alternative for centralized state estimation (CSE) in power system. Especially, taking into account the future power grid, so called smart grid in which bi-dire…

Survey on the Advancements of Dielectric Fluids and Experiment Studies for Distribution Power Transformers Open

Salvador Carvalhosa, Hélder Leite, Fernando A. Branco, Carlos A. Sá, A. Machado e Moura , et al. · 2021

The main objective of this work is to summarize the most commonly used dielectric fluids in the power distribution transformers, as well as to discuss what are the latest and the rationale behind those trends. The favorable and unfavorable…

Integration of Voltage Source Converters in Steady-State RMS Short-Circuit Analysis Open

Carlos Coelho Teixeira, Hélder Leite · 2021

Voltage source converters (VSCs) are self-commutated converters able to generate AC voltages with or without the support of an AC connecting grid. VSCs allow fast control of active and reactive powers in an independent way. VSCs also have …

Optimal partitioning in distributed state estimation considering a\n modified convergence criterion Open

Sajjad Asefi, Elena Gryazina, Hélder Leite · 2021

Distributed state estimation (DSE) is considered as a more robust and\nreliable alternative for centralized state estimation (CSE) in power system.\nEspecially, taking into account the future power grid, so called smart grid in\nwhich bi-d…

Communication Requirements for a Hybrid VSC Based HVDC/AC Transmission Networks State Estimation Open

Motaz Ayiad, Emily Maggioli, Hélder Leite, Hugo Martins · 2021

The communication infrastructure of the modern Supervisory, Control and Data Acquisition (SCADA) system continues to enlarge, as hybrid High Voltage Direct Current (HVDC)/Alternating Current (AC) networks emerge. A centralized SCADA faces …

State Estimation for Hybrid VSC Based HVDC/AC: Unified Bad Data Detection Integrated With Gaussian Mixture Model Open

Motaz Ayiad, Hélder Leite, Hugo Martins · 2021

The High Voltage Direct Current (HVDC) is an emerging technology that transmits power over long distances and at a higher capacity than the traditional AC systems. Integration of HVDC into modern power networks requires vital modification …

State Estimation for Hybrid VSC Based HVDC/AC Transmission Networks Open

Motaz Ayiad, Hélder Leite, Hugo Martins · 2020

As the integration of High Voltage Direct Current (HVDC) systems on modern power networks continues to expand, challenges have appeared in different fields of the network architecture. In the Supervisory, Control and Data Acquisition (SCAD…

Performance of Composite Outdoor Insulator Under Superimposed Direct and Switching Impulse Voltages Open

Davide Pinzan, Fábio Cardinale Branco, A. Haddad, Mohammed El Amine Slama, Maurizio Albano , et al. · 2020

In High Voltage Direct Current (HVDC) systems, composite outdoor insulators play a critical role and focus is needed on the research of their failure. In the case of a pole to ground fault of a bipolar scheme, the healthy pole experiences …

Exploiting OLTC and BESS Operation Coordinated with Active Network Management in LV Networks Open

Konstantinos Kotsalos, Ismael Miranda, José Luís Domínguez‐García, Hélder Leite, Nuno Silva , et al. · 2020

The large number of small scale Distributed Energy Resources (DER) such as Electric Vehicles (EVs), rooftop photovoltaic installations and Battery Energy Storage Systems (BESS), installed along distribution networks, poses several challeng…

Integrating Hybrid Off-grid Systems with Battery Storage: Key Performance Indicators Open

Luís Miguel Costa, Marta Ribeiro, Ismael Miranda, Hélder Leite · 2019

A clear opportunity exists for the integration of Battery Energy Storage Systems (BESS) in hybrid off-grid applications, i.e., isolated grids with renewable sources (e.g. photovoltaic, wind) and small-scale diesel generators. In these appl…

A centralized control for the operation of low voltage distribution networks with multiple Distributed Energy Resources Open

Konstantinos Kotsalos, Ismael Miranda, Nuno A. Silva, Hélder Leite · 2019

This paper proposes a secondary substation centered control approach which deals with the effective coordination of multiple Distributed Energy Resources (DER) connected along the LV grid. The presented tool manages and schedules the flexi…

A Horizon Optimization Control Framework for the Coordinated Operation of Multiple Distributed Energy Resources in Low Voltage Distribution Networks Open

Konstantinos Kotsalos, Ismael Miranda, Nuno Silva, Hélder Leite · 2019

In recent years, the installation of residential Distributed Energy Resources (DER) that produce (mainly rooftop photovoltaics usually bundled with battery system) or consume (electric heat pumps, controllable loads, electric vehicles) ele…

Wavelet-based analysis and detection of traveling waves due to DC faults in LCC HVDC systems Open

Daniel Marques da Silva, Flávio B. Costa, Vladimiro Miranda, Hélder Leite · 2018

Scheduling of operation in Low Voltage distribution networks with multiple Distributed Energy Resources Open

Konstantinos Kotsalos, Nuno A. Silva, Ismael Miranda, Hélder Leite · 2018

The goal of this work is to propose a tool that optimizes the operational planning of the Low Voltage (LV) grid at the day-ahead stage. The multiple Distributed Energy Resources (DER) are incorporated within a three-phase Optimal Power Flo…

Optimal recloser deployment to leverage self-healing: a techno-economic robustness assessment Open

Eduardo Rodrigues, Ismael Miranda, Nuno Silva, Hélder Leite · 2017

This study presents a techno-economic robustness assessment over coordinated protection schemes using reclosers to leverage self-healing in distribution networks. A methodology to assess the optimal deployment of reclosers in overhead dist…

Unidirectional Protection Strategy for Multi-terminal HVDC Grids Open

Ataollah Mokhberdoran, Nuno A. Silva, Hélder Leite, Adriano Carvalho · 2016

Protection issue is identified as the main drawback of emerging multi-terminal HVDC grids. Multi-terminal HVDC grid demands fast short circuit fault current interruption. Fast DC circuit breakers as a promising solution can be implemented …

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