2021
Authors
Reiz, C; Leite, JB;
Publication
IEEE TRANSACTIONS ON POWER DELIVERY
Abstract
The sustainable development of power distribution systems must evolve into smart grids, where advanced automation with fast communication channels is essential. The analysis of their behavior uses the Hardware-In-the-Loop simulation for studying normal and critical operating conditions. In this work, we propose a hybrid technique for transient simulation in distribution systems by combining the high sample rate of the time domain models for voltage profile and electrical current monitoring with the processing speed of algorithms that operate the quasi-stationary, or permanent, phasor models. The proposed simulation platform is also based on the state of the art of standardized communication protocols of the power system. Its evaluation is performed using the comparison with specialized commercial software to assess the transient simulation. The time overcurrent protection function and the verification of messages exchanged between the simulator and the tested device highlights the applicability of the proposed methodology.
2021
Authors
Reiz C.; Leite J.B.;
Publication
2021 IEEE PES Innovative Smart Grid Technologies Conference - Latin America, ISGT Latin America 2021
Abstract
Integration of distributed generation in power distribution networks provides many advantages and challenges to electric power system. Among challenges are the increase in levels of short-circuit currents and changes of power flow direction. These characteristics can interfere in the interruption capacity of protection devices, which are responsible for maintaining the integrity of distribution networks. Therefore, it is essential to understand the effects of distributed generation on protection systems to determine strategies that aim to solve the challenges imposed by this technology. The present work, first, proposes the mathematical formulation to coordinate overcurrent relays and fuse links, considering permanent and temporary faults. The solution is obtained through a dedicated genetic algorithm. Subsequently, this solution method is analyzed under different levels of penetration of distributed generators, allowing to identify points most susceptible to loss of coordination.
2021
Authors
Reyes Batlle, M; Gabriel, MF; Rodriguez Exposito, R; Felgueiras, F; Sifaoui, I; Mourao, Z; Fernandes, ED; Pinero, JE; Lorenzo Morales, J;
Publication
MICROBIOLOGYOPEN
Abstract
Recently, indoor swimming pool activities have increased to promote health-enhancing physical activities, which require establishing suitable protocols for disinfection and water quality control. Normally, the assessment of the microbial quality of the water in the pools only considers the presence of different bacteria. However, other less frequent but more resistant pathogens, such as free-living amoebas (FLA), are not contemplated in both existing recommendation and research activities. FLA represent a relevant human health risk, not only due to their pathogenicity but also due to the ability to act as vehicles of other pathogens, such as bacteria. Therefore, this work aimed to study the physicochemical characteristics and the occurrence of potentially pathogenic FLA and bacteria in water samples from 20 public indoor swimming facilities in Northern Portugal. Our results showed that some swimming pools presented levels of pH, free chlorine, and conductivity out of the recommended limits. Pathogenic FLA species were detected in two of the facilities under study, where we also report the presence of both, FLA and pathogenic bacteria. Our findings evidence the need to assess the occurrence of FLA and their existence in the same environmental niche as pathogenic bacteria in swimming pool facilities worldwide and to establish recommendations to safeguard the health of the users.
2021
Authors
Heinrichs, HU; Mourao, Z; Venghaus, S; Konadu, D; Gillessen, B; Vogele, S; Linssen, J; Allwood, J; Kuckshinrichs, W; Robinius, M; Stolten, D;
Publication
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
Abstract
While it is generally accepted that our fossil fuel-dominated energy systems must undergo a sustainable transition, researchers have often neglected the potential impacts of this on water and land systems. However, if unintended environmental impacts from this process are to be avoided, understanding its implications for land use and water demand is of crucial importance. Moreover, developed countries may induce environmental stress beyond their own borders, for instance through extensive imports of bioenergy. In this paper, Germany serves as an example of a developed country with ambitious energy transformation targets. Results show that in particular, the politically-driven aspiration for more organic farming in Germany results in a higher import quota of biomass, especially biofuels. These imports translate into land demand, which will exceed the area available in Germany for bioenergy by a factor of 3-6.5 by 2050. As this will likely bring about land stress in the respective exporting countries, this effect of the German energy transformation ought to be limited as much as possible. In contrast, domestic water demand for the German energy system is expected to decrease by over 80% through 2050 due to declining numbers of fossil-fuelled power plants. However, possible future irrigation needs for bioenergy may reduce or even counterbalance this decreasing effect. In addition, energy policy targets specific to the transport sector show a high sensitivity to biomass imports. In particular, the sector-specific target for greenhouse gas reductions will seemingly promote biomass imports, leading to the above-described challenges in the pursuit of sustainability.
2021
Authors
Cardoso, S; Mourao, Z; Pinho, C;
Publication
CASE STUDIES IN THERMAL ENGINEERING
Abstract
This is the study of the thermal efficiency performance of a possible 1-ha solar pond located at Caota beach, in Benguela, Angola. During the first year of operation there was no energy extraction from the pond and the water temperature in the lowest and denser layer reached 93 degrees C. From the second year onwards thermal energy was extracted. Two scenarios were adopted, water heating from 40 to 60 degrees C or water heating from 50 to 70 degrees C. Yearly 1600 MWh and 700 MWh could be extracted, in the first and or the second scenario. Operating regimes of 8, 12 or 24 h/day were considered. Based on the total pond incident solar energy, the overall energy efficiency of the pond is in the 2 to 5 % range, while the exergy efficiency is in the 0.4 to 2.6 % range. The repartition of the pond energy losses is also quantified.
2021
Authors
Gabriel, MF; Felgueiras, F; Batista, R; Ribeiro, C; Ramos, E; Mourao, Z; Fernandes, ED;
Publication
ENVIRONMENTAL RESEARCH
Abstract
Exposure to air pollution in early years can exacerbate the risk of noncommunicable diseases throughout childhood and the entire life course. This study aimed to assess temperature, relative humidity (RH), carbon dioxide (CO2) and monoxide (CO), particulate matter (PM2.5, PM10), ultrafine particles, nitrogen dioxide (NO2), ozone (O3), formaldehyde, acetaldehyde and volatile organic compounds (VOC) levels in the two rooms where infant twins spend more time at home (30 dwellings, Northern Portugal). Findings showed that, in general, the worst indoor environmental quality (IEQ) settings were found in bedrooms. In fact, although most of the bedrooms surveyed presented adequate comfort conditions in terms of temperature and RH, several children are sleeping in a bedroom with improper ventilation and/or with a significant degree of air pollution. In particular, mean concentrations higher than recommended limits were found for CO2, PM2.5, PM10 and total VOC. Additionally, terpenes and decamethylcyclopentasiloxane were identified as main components of emissions from indoor sources. Overall, findings revealed that factors related to behaviors of the occupants, namely related to a conscientious use of cleaning products, tobacco and other consumer products (air-fresheners, incenses/candles and insecticides) and promotion of ventilation are essential for the improvement of air quality in households and for the promotion of children's health.
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