EOL - Comunicações em actas de encontros científicos internacionais
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- Uma abordagem espectral à geração de séries correlacionadas de ventoPublication . Aguiar, Ricardo; Estanqueiro, Ana; Saraiva, J. A. Gil
- An optimized probabilistic forecasting approach for hybridized wind power plantsPublication . Couto, António; Algarvio, Hugo; Estanqueiro, AnaABSTRACT: Accurate forecasts are essential for efficiently integrate variable renewable power plants into power systems and electricity markets. Since hybrid power plants are a new area of research, several key challenges need to be addressed. This work presents a probabilistic power forecast approach to hybridised wind power plants with solar power. The forecasting metho dology uses a sequential forward feature selection algorithm, employing distinct objective functions and an artificial neural network approach. The probabilistic power forecasts are obtained using a quantile spline regression technique. The approach supports the identification of the: i) optimal quantile and ii) exogenous features (e.g., meteorological input features from numerical weather prediction – NWP models) to increase the profitability of the hybrid power plants in an electricity market environment. As expected, hybridization increases the remuneration of the producer when compared to existing wind plants, regardless of complementarity levels. This increase in remuneration of hybrid plants is superior for the highest generation complementarity case. The use of quantiles to calibrate the forecast approach proves to be crucial for increasing the remuneration compared to the traditional deterministic approach based on the power forecast expected value.
- Assessment of Power Quality Characteristics of Wind FarmsPublication . Estanqueiro, Ana; Tande, John O.; Lopes, J. PeçasIn this paper the main parameters to assess the power quality of grid embedded wind farms are presented. International standards to assess and quantify the power quality of grid connected wind turbines exist for some years now, and are here extrapolated to wind farms aggregates when possible being the correspondent methodologies identified in the document. Recently, the grid code requirements posed a novel challenge to this technologic area, particularly since they were issued with national or local objectives and without particular normalized global concerns. The form how the international standards are evolving in order to cope both with the power systems industry local requirements, but also with the global wind turbine manufacturers principles is addressed in the paper.
- Assessment of PV and wind microgeneration's impact in the power quality of low and medium voltage distribution networksPublication . Bonifácio, Paulo; Viana, Susana; Rodrigues, L.; Estanqueiro, AnaElectric power systems face an ever-growing penetration (PV) and other microgeneration as well as non-linear loads such as electric vehicles. This is a common link between these : the extensive use of power electronics converters. These devices are a source of medium-to-high frequency harmonic distortion and their impact on the local distribution grid must be carefully assessed in order to evaluation possible network unbalances, demaging power line resonance conditions, transformer core saturation and overhearing.
- Assessment of the sustainable offshore wind potential in PortugalPublication . Costa, Paula Silva; Simões, Teresa; Estanqueiro, AnaThe sustainable offshore wind potential for the west and south coasts of Portugal is presented. Results were carried out using an atmospheric mesoscale model and GIS tools. Unlike previous common opinions, the preliminary results show the existence of interesting areas for the developing of offshore wind parks.
- Barriers (and Solutions...) to Very High Wind Penetration in Power SystemsPublication . Estanqueiro, Ana; Jesus, J.M. Ferreira; Ricardo, João; Santos, Amarante dos; Lopes, J. PeçasIn this paper the existing technical barriers that prevent the accomplishment of a very high wind generation penetration in a power system are presented. Since several countries and regions in Europe are already experiencing such high wind penetration or, as a minimum, planning their grids and operation strategies to cope with wind penetration from a high to a very high level, the solutions already identified for the most common constraints are also identified.
- Building a wind atlas for mainland Portugal using a weather type classificationPublication . Costa, Paula Silva; Estanqueiro, Ana; Miranda, PedroA weather type classification scheme was implemented for the construction of a wind atlas to mainland Portugal. This methodology produced 26 different weather types computed by geostrophic vorticity at mean sea level pressure. Applying a simple calculus scheme, it is possible to find the most likely representative day for each weather type if a meteorological database with wind data is available. Each selected day can be simulated by a mesoscale model (e.g.MM5) being possible to construct the final wind atlas through the sum of the simulated days, weighted by the respective frequency factor. In this paper, it is shown that the results obtained by the application of this classification scheme for mean wind and energy density fields are very similar to long term simulations.
- Caracterização do potencial eólico em ambiente urbanoPublication . Simões, Teresa; Estanqueiro, AnaRESUMO: Nas últimas duas décadas, a capacidade eólica instalada no mundo cresceu de forma marcante. O desenvolvimento de projetos de energia eólica onshore e offshore foi recentemente seguida pelo interesse em integrar projetos eólicos em cidades inteligentes. Neste contexto surgiu a necessidade de desenvolver metodologias adequadas e menos onerosas de avaliação do recurso eólico urbano, e de planeamento da integração de turbinas eólicas nestes ambientes. Assim, apresenta-se uma metodologia para a avaliação do recurso eólico urbano baseada na construção de uma superfície de cotas envolvendo o edificado, transformando assim, a área urbana num terreno de orografia muito complexa, e uma metodologia de planeamento da integração de turbinas eólicas em contexto urbano recorrendo a sistemas de informação geográfica. Estas metodologias são validadas com dados experimentais e aplicadas a um caso de estudo.
- Caracterização do vento urbano com recurso a um modelo CFD open-source : aplicação a uma cidade portuguesaPublication . Costa, Paula Silva; Simões, Teresa; Estanqueiro, AnaRESUMO: Neste trabalho, é apresentado um estudo de avaliação preliminar do recurso eólico numa área urbana através do uso de um modelo digital de terreno urbano (DTM urbano) desenvolvido em trabalhos anteriores pelos autores, particularmente para aplicação em modelos comerciais CFD. Neste trabalho pretendeu-se utilizar um modelo comercial de referência do sector de energia eólica para o cálculo do recurso do vento, o modelo WaspEngineering bem como o modelo freeware CDF-OpenFoam, e avaliar o impacto das estimativas obtidas por ambos os modelos através do modelo digital de superfí-cie. Um mastro anemométrico equipado com anemômetro e cata-vento foi instalado no telhado de um edifício dentro da área urbana selecionada para fins de validação das estimativas de vento. O modelo digital de terreno urbano permite a introdução da descrição do tecido urbano acoplado à orografia da região como se fosse um terreno complexo. Os resulta-dos obtidos mostram que a metodologia do terreno digital urbano é adequada para estudar o comportamento do vento urbano em altíssima resolução espacial em áreas urbanas, uma vez que estão de acordo com as observações. Também a metodologia relacionada ao desenvolvimento do DTM urbano mostra-se adequada para uso em modelos de CFD comerci-ais ou freeware.
- Contribution of energy storage for large-scale integration of variable generationPublication . Estanqueiro, Ana; Ardal, Atle Rygg; O'Dwyer, Ciara; Flynn, Damian; Huertas-Hernando, Daniel; Lew, Debra; Gomez-Lázaro, E.; Carlini, Enrico Maria; Solvang, Eivind; Ela, Erik; Kiviluoma, Juha; Rodrigues, L.; Amelin, MikaelThe amount of wind power and other timevariable non-dispatchable renewable energy sources (VRES) such as photovoltaics (PV) is rapidly increasing in the world. Several power systems in Europe are already facing a very high penetration from variable renewables which is posing concerns on the operational stability limits that are being surpassed for extreme RES generation conditions. Most transmission system operators are defining VRES limits of penetration, thus, requiring the renewable energy excess to be curtailed, exported or stored. Energy storage may play a relevant role in maximizing the long term penetration of VRES if used as a technical mean to regulate the daily, weekly and annual profiles of variable generation (VG). This paper reviews the storage technologies that are available and may be used on a power system scale and performs a cost/benefit analysis discussing their advantages and disadvantages for the integration of fastgrowing renewables, such as wind power and PV.