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Publicações

Publicações por CPES

2020

BESS modeling: Investigating the role of auxiliary system consumption in efficiency derating

Autores
Rancilio G.; Merlo M.; Lucas A.; Kotsakis E.; Delfanti M.;

Publicação
2020 International Symposium on Power Electronics Electrical Drives Automation and Motion Speedam 2020

Abstract
Large-scale Battery Energy Storage System (BESS) capacity installed for stationary applications is rising in the first decades of 21st century. Business models related to BESS highly depend on BESS lifetime. BESS lifetime can be preserved only if accurate thermal management of the assets allows to keep it at design temperature. Auxiliary systems' needs for cooling and heating the BESS cannot be disregarded while modeling the real-world operation of these facilities. In this paper we propose an improved protocol for organic modeling of large-scale BESS grid-connected. We assess the share of losses and the operational efficiency related to the provision of ancillary services to the network by BESS in different seasons and different working conditions. We highlight that BESS efficiency increases in case the system is constantly exploited, avoiding time idle or at low power. The model proposed, with respect to standard techniques, allows to better represent BESS performance. Indeed, just by disregarding the losses related to thermal management of the assets (as it is for standard modeling techniques), errors committed are up to 10%.

2020

The digital terrain model in the computational modelling of the flow over the Perdigao site: the appropriate grid size

Autores
Palma, JMLM; Silva, CAM; Gomes, VC; Lopes, AS; Simoes, T; Costa, P; Batista, VTP;

Publicação
WIND ENERGY SCIENCE

Abstract
The digital terrain model (DTM), the representation of earth's surface at regularly spaced intervals, is the first input in the computational modelling of atmospheric flows. The ability of computational meshes based on high- (2 m; airborne laser scanning, ASL), medium- (10 m; military maps, Mil) and low-resolution (30 m; Shuttle Radar Topography Mission, SRTM) DTMs to replicate the Perdigao experiment site was appraised in two ways: by their ability to replicate the two main terrain attributes, elevation and slope, and by their effect on the wind flow computational results. The effect on the flow modelling was evaluated by comparing the wind speed, wind direction and turbulent kinetic energy using VENTOS (R)/2 at three locations, representative of the wind flow in the region. It was found that the SRTM was not an accurate representation of the Perdigao site. A 40m mesh based on the highest-resolution data yielded an elevation error of less than 1.4m and an RMSE of less than 2.5m at five reference points compared to 5.0m in the case of military maps and 7.6m in the case of the SRTM. Mesh refinement beyond 40m yielded no or insignificant changes on the flow field variables, wind speed, wind direction and turbulent kinetic energy. At least 40m horizontal resolution - threshold resolution based on topography available from aerial surveys is recommended in computational modelling of the flow over Perdigao.

2020

APLICAÇÃO DE CONTORNOS ATIVOS NA EXTRAÇÃO DE FEIÇÕES EM IMAGENS LANDSAT 8 E CBERS 4

Autores
Reiz, C; Zanin, RB; Martins, EFdO; Filgueiras, JLD; Evaristo, JW;

Publicação
As Ciências Exatas e da Terra e a Interface com vários Saberes 2

Abstract

2020

Simulação Híbrida para Monitoramento de Tensão e Corrente em Redes de Distribuição com Geração Distribuída

Autores
Reiz, C; B. Leite, J;

Publicação
Anais do Congresso Brasileiro de Automática 2020

Abstract
O sistema de distribuição de energia elétrica é a parcela do sistema de potência mais vulnerável aos eventos de interrupção, originados por fatores naturais externos ou intrínsecos aos equipamentos elétricos. Na mitigação dos impactos desses eventos, simuladores digitais em tempo real são utilizados na obtenção dos transitórios do sistema elétrico, todavia, essa técnica demanda grande esforço computacional. Nesse contexto, propõe-se uma técnica híbrida para simulação do transitório em sistemas de distribuição, combinando a alta taxa de amostragem dos modelos no domínio do tempo para monitoramento de tensão e corrente com a velocidade de processamento dos algoritmos que operam os modelos fasoriais em regime quase-estacionário, ou permanente. A metodologia proposta também permite considerar diferentes tecnologias de geradores distribuídos acoplados na rede. Os resultados dos testes realizados indicam a consistência da metodologia proposta, representando o comportamento do transitório no sistema de distribuição de energia elétrica. Todas as simulações realizadas são comparadas com valores amostrais obtidos usando um software comercial especializado.

2020

Comprehensive assessment of the indoor air quality in a chlorinated Olympic-size swimming pool

Autores
Felgueiras, F; Mourao, Z; Morais, C; Santos, H; Gabriel, MF; Fernandes, ED;

Publicação
ENVIRONMENT INTERNATIONAL

Abstract
Elite swimmers and swimming pool employees are likely to be at greater health risk due to their regular and intense exposure to air stressors in the indoor swimming pool environment. Since data on the real long-term exposure is limited, a long-term monitoring and sampling plan (22 non-consecutive days, from March to July 2017) was carried out in an indoor Olympic-size pool with a chlorine-based disinfection method to characterize indoor environments to which people involved in elite swimming and maintenance staff may be exposed to. A comprehensive set of parameters related with comfort and environmental conditions (temperature, relative humidity (RH), carbon dioxide (CO2) and monoxide and ultrafine particles (UFP)) were monitored both indoors and outdoors in order to determine indoor-to-outdoor (I/O) ratios. Additionally, an analysis of volatile organic compounds (VOC) concentration and its dynamics was implemented in three 1-hr periods: early morning, evening elite swimmers training session and late evening. Samplings were simultaneously carried out in the air layer above the water surface and in the air surrounding the pool, selected to be representative of swimmers and coaches/employees' breathing zones, respectively. The results of this work showed that the indoor climate was very stable in terms of air temperature, RH and CO 2 . In terms of the other measured parameters, mean indoor UFP number concentrations (5158 pt/cm(3)) were about 50% of those measured outdoors whereas chloroform was the predominant substance detected in all samples collected indoors (13.0-369.3 mu g/m(3)), among a varied list of chemical compounds. An I/O non-trihalomethanes (THM) VOC concentration ratio of 2.7 was also found, suggesting that, beyond THM, other potentially hazardous VOC have also their source(s) indoors. THM and non-THM VOC concentration were found to increase consistently during the evening training session and exhibited a significant seasonal pattern. Compared to their coaches, elite swimmers seemed to be exposed via inhalation to significantly higher total THM levels, but to similar concentrations of non-THM VOC, during routine training activities. Regarding swimming employees, the exposure to THM and other VOC appeared to be significantly minimized during the early morning period. The air/water temperature ratio and RH were identified as important parameters that are likely to trigger the transfer processes of volatile substances from water to air and of their accumulation in the indoor environment of the swimming pool, respectively.

2020

Assessment of indoor air conditions in households of Portuguese families with newborn children. Implementation of the HEALS IAQ checklist

Autores
Gabriel, MF; Felgueiras, F; Fernandes, M; Ribeiro, C; Ramos, E; Mourao, Z; Fernandes, ED;

Publicação
ENVIRONMENTAL RESEARCH

Abstract
Conducting epidemiological and risk assessment research that considers the exposome concept, as in the case of HEALS project, requires the acquisition of higher dimension data sets of an increased complexity. In this context, new methods that provide accurate and interpretable data summary on relevant environmental factors are of major importance. In this work, a questionnaire was developed to collect harmonized data on potential pollutant sources to air in the indoor environment where children spend an important part of their early life. The questionnaire was designed in a user friendly checklist format to be filled out at the maternity in ten European cities. This paper presents and discusses the rationale for the selection of the questionnaire contents and the results obtained from its application in the households of 309 HEALS-enrolled families with babies recently born in Porto, Portugal. The tool was very effective in providing data on the putative air pollution sources in homes, with special focus on the bedroom of the newborns. The data collected is part of a wider effort to build the databases and risk assessment models of the HEALS project. The results of the analysis of the collected data suggest that, for the population under study, the main concerns on early life exposures at home can be related to emissions from the use of household solid fuels, indoor tobacco, household cleaning products, fragranced consumer products (e.g. air fresheners, incense and candles), moisture-related pathologies and traffic-related outdoor pollution. Furthermore, it is anticipated that the tool can be a valuable means to empower citizens to actively participate in the control of their own exposures at home. Within this context, the application of the checklist will also allow local stakeholders to identify buildings presenting most evident IAQ problems for sampling or intervention as well as to guide them in preparing evidence-based educational/awareness campaigns to promote public health through creating healthy households.

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