http://hdl.handle.net/10174/37677 2026-05-08T01:53:50Z 2026-05-08T01:53:50Z Esposito, Marcelo Prestes Kunz, Matheus Mesquita Bruel, Gabriela Belén Cristóbal López, Ana Luis André Pereira Fialho, Luis Mesbahi, Oumaima http://hdl.handle.net/10174/41960 2026-05-06T13:43:40Z 2025-01-01T00:00:00Z

Title: Dry Transformer Specification for Photovoltaic Power Plants: Investigation Into the K-Factor and the Use of 800VAC Disconnectors Authors: Esposito, Marcelo; Prestes Kunz, Matheus; Mesquita Bruel, Gabriela; Belén Cristóbal López, Ana; Luis André Pereira Fialho, Luis; Mesbahi, Oumaima Abstract: Although there are several transformer manufacturers in Brazil dedicated to photovoltaic power generation, the connection between inverters with a nominal output voltage of 800VAC and the protection system installed before the step-up transformer is still complex. In this paper, issues related to design, installation and supply of equipment and preventive and corrective maintenance are explored. Operating data is presented for two photovoltaic plants (PV), one has a power of 444kWp and the other 406kWp, which share the same installation design. Both plants experienced faults including, in the worst case, a short circuit followed by a fire caused by the general disconnector. The transformers of 500kVA and K1 factor were assessed after the accidents and showed no faults in the measurements taken at the substations. The installation of disconnect switches with a nominal operating voltage (Ue) equal to 690VAC was identified as the cause of the short circuit. The quality of the equipment was investigated and an analysis of the operating temperature of the transformers was carried out. Possible causes and effects, such as the presence of harmonics and inverter failures, were explored. Given the high cost of circuit breakers for 800VAC/400A Ue and transformers with a K4 factor, the solution found was to repair them and replace the faulty cables and switch-disconnectors with products dedicated to photovoltaic systems. The use of fuses in the AC circuit made the disconnection difficult and impaired the safety in several aspects.

2025-01-01T00:00:00Z Couto, Flavio Tiago Santos, Filippe L. M. Campos, Cátia Purificação, Carolina Andrade, Nuno López-Vega, Juan Manuel Lacroix, Matthieu http://hdl.handle.net/10174/41952 2026-05-05T14:06:56Z 2025-08-19T23:00:00Z

Title: ANÁLISE EXPLORATÓRIA DO USO DA MODELAGEM ATMOSFÉRICA SOBRE OS INCÊNDIOS FLORESTAIS NO PANTANAL Authors: Couto, Flavio Tiago; Santos, Filippe L. M.; Campos, Cátia; Purificação, Carolina; Andrade, Nuno; López-Vega, Juan Manuel; Lacroix, Matthieu Abstract: O estudo discute de forma exploratória as condições atmosféricas favoráveis à evolução dos incêndios florestais no Pantanal em 12 de novembro de 2023. Esses episódios foram marcados por dois períodos de rápida expansão do fogo, primeiro no início da tarde e outro à noite. O estudo usa um conjunto de observações de satélite e estações meteorológicas, as quais ajudaram a identificar o fogo e algumas condições meteorológicas na superfície. Além disso, o Fire Weather Index (FWI) no Pantanal foi analisado para um período de 44 anos. No entanto, esse conjunto de dados não foi suficiente para explicar completamente o comportamento do fogo naquele dia. Nesse contexto, a modelagem atmosférica foi aplicada para encontrar as possíveis causas do comportamento do fogo em dois períodos. O modelo Meso-NH foi configurado com dois domínios aninhados e resoluções horizontais de 2500 m e 500 m. Os resultados mostraram uma tendência positiva do FWI nas últimas décadas, bem como uma clara sazonalidade para os valores máximos no ano de 2023. A simulação indicou condições favoráveis à ignição do fogo, e o campo de rajadas de vento mostrou ventos moderados em ambos os períodos, mas causados por diferentes forçantes. No início da tarde, a circulação em grande escala favoreceu a propagação do fogo, enquanto à noite uma frente de rajada foi observada. O estudo destaca o papel das condições meteorológicas na escala sub-diária, em particular para mudanças repentinas do vento à superfície ao longo do dia. Esse resultado deve ser considerado ao examinar o perigo de fogo e o planejamento das ações de combate aos incêndios na região.

2025-08-19T23:00:00Z Couto, Flavio Tiago Campos, Cátia Purificação, Carolina Santos, Filippe Lemos Maia Andrade, Hugo Nunes Andrade, Nuno Nunes, André Becker Guiomar, Nuno Salgado, Rui http://hdl.handle.net/10174/41685 2026-03-13T11:13:47Z 2025-09-10T23:00:00Z

Title: Synoptic and Regional Meteorological Drivers of a Wildfire in the Wildland–Urban Interface of Faro (Portugal) Authors: Couto, Flavio Tiago; Campos, Cátia; Purificação, Carolina; Santos, Filippe Lemos Maia; Andrade, Hugo Nunes; Andrade, Nuno; Nunes, André Becker; Guiomar, Nuno; Salgado, Rui Abstract: A major fire occurred in the wildland–urban interface in southern Portugal, on 13 July 2022, becoming uncontrolled due to weather conditions. This study investigates how atmospheric dynamics increased fire danger in Mainland Portugal during early July 2022. The synoptic circulation from European Centre for Medium-Range Weather Forecasts (ECMWF) analysis and mesoscale conditions from Meso-NH model simulation at 1.5 km resolution revealed atmospheric conditions before and during the fire. Fire risk was assessed using the Fire Weather Index (FWI) from Meso-NH outputs. A blocking pattern was configured by an upper-level low-pressure system in early July, remaining semi-stationary west of Mainland Portugal until 18 July. The counter-clockwise circulation of the cut-off low resulted in dry, warm air advection from North Africa, enhancing fire danger over the Iberian Peninsula. In southern Portugal, a jet-like wind with strong east/southeasterly flow from Gibraltar Strait favored rapid fire spread. This circulation below 1 km altitude from the Mediterranean Sea enhanced fire danger through strong winds, independent of the large-scale blocking pattern. This study presents an atmospheric scenario for evaluating fire danger in Southern Portugal, important for pre-firefighting management that complemented previous studies for the region. Also, high-resolution FWI calculations using Meso-NH emphasized the importance of improved temporal and spatial resolution for fire danger assessment.

2025-09-10T23:00:00Z Couto, Flavio Tiago Santos, Filippe L. M. Campos, Cátia Purificação, Carolina Andrade, Nuno López-Vega, Juan Manuel Lacroix, Matthieu http://hdl.handle.net/10174/41684 2026-03-13T11:13:25Z 2025-08-19T23:00:00Z

Title: EXPLORATORY ANALYSIS OF ATMOSPHERIC MODELLING USE OVER PANTANAL WILDFIRES Authors: Couto, Flavio Tiago; Santos, Filippe L. M.; Campos, Cátia; Purificação, Carolina; Andrade, Nuno; López-Vega, Juan Manuel; Lacroix, Matthieu Abstract: The study discusses in an exploratory way the atmospheric conditions leading to several fires in the Pantanal on November 12, 2023. These episodes were marked by two periods of maximum fire expansion, first in the early afternoon and another in the evening. The study is based on a set of observations from satellites and weather stations, which helped to identify these fires and some meteorological conditions at the surface. In addition, the Fire Weather Index (FWI) in the Pantanal was analyzed for a 44-year period. However, this dataset was not enough to completely explain the fire behavior on that day. In this context, atmospheric modeling was applied to find the possible causes of fire behavior in these two periods. The Meso-NH model was run with two nested domains of horizontal resolutions of 2500 m and 500 m. The results showed a positive trend of FWI in the last decades and a clear seasonality for the maximum values in 2023. Also, the simulation indicated favorable weather conditions for fire ignition, given the high temperatures and low relative humidity. However, the wind gust field showed moderate gusty winds in both periods but caused by different forces. In the early afternoon, the larger scale circulation favored fire propagation, whereas in the evening fire spread by a gust front. Furthermore, the findings highlight the role of weather conditions on a sub-daily scale, with sudden changes in surface winds throughout the day, which is strongly recommended to be considered when examining fire danger and firefighting action plans in the region.

2025-08-19T23:00:00Z