EOL - Comunicações em actas de encontros científicos internacionais
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- 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.
- 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.
- Quadro regulatório para energias renováveis em ambiente urbano em PortugalPublication . Simões, Teresa; Daniel, V.; Estanqueiro, AnaRESUMO: Nos últimos anos a preocupação das entidades governamentais com o aquecimento global conduziu ao lançamento de várias iniciativas europeias e nacionais visando a redução das emissões de gases de efeito de estufa e da dependência em combustíveis fósseis. A preocupação em tornar mais eficiente o consumo de energia, tem conduzido nos últimos anos à adoção de medidas de sensibilização das sociedades para a utilização eficiente de recursos energéticos. Assim, surgiram nos anos mais recentes conceitos como, Cidades Inteligentes, os quais recorrem à utilização de sistemas de energias renováveis para produção de eletricidade. Neste contexto, à semelhança do que ocorreu com a energia eólica convencional, foi necessário criar políticas incentivadoras à instalação de sistemas renováveis para a produção de eletricidade no contexto urbano e rural. Nesta sequência, surgiu em Portugal nos últimos anos, um novo quadro legislativo. Este incide especialmente na regulamentação da capacidade a instalar e no tarifário de venda da energia referente a cada tecnologia de produção. Assim, apresenta-se a regulamentação aplicada em Portugal, com a descrição dos aspetos mais relevantes dos diplomas legais publicados nesta área até à presente data e o seu impacto no crescimento deste setor das energias renováveis, bem como um caso de estudo ilustrativo.
- 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.
- Simplified wind turbine models for wind energy integration into power systemsPublication . Honrubia-Escribano, A.; Martín-Martínez, Sergio; Estanqueiro, Ana; Jiménez-Buendía, F.; Gomez-Lázaro, E.; Fuentes-Moreno, J. A.This paper analyses the boundaries of simplified wind turbine models used to represent the behavior of wind turbines in order to conduct power system stability studies. Based on experimental measurements, the response of recent simplified (also known as generic) wind turbine models that are currently being developed by the International Standard IEC 61400-27 is compared to complex detailed models elaborated by wind turbine manufacturers. This International Standard, whose Technical Committee was convened in October 2009, is focused on defining generic simulation models for both wind turbines (Part 1) and wind farms (Part 2). The results of this work provide an improved understanding of the usability of generic models for conducting power system simulations.
- Dynamics of knowledge production and technology diffusion: insights from the emergence of wind energyPublication . Sousa, Cristina; Bento, Nuno; Fontes, MargaridaThe objective of this paper is to contribute to a better understanding of the relation between the dynamics of knowledge production and technology diffusion along the process of emergence of a new technology, as it unfolds in diverse spatial locations. For this purpose, the paper traces the process of knowledge production over time expressed in the number of scientific publications and assesses how its dynamics relate with those of technology up scaling and diffusion, for the case of a new renewable energy technology: wind power. It also compares these processes in different spatial areas, looking at similarities and differences in the evolving patterns in initial markets and follower regions. In order to trace the dynamics of knowledge production we conduct a bibliometric analysis, using data collected from the Thomson Reuters Web of Science database (for the period 1970-- 2012). In order to trace the diffusion dynamics we use data collected on both unit scale of turbines and installed capacity of wind power (starting in late 1970s), following the empirical scaling methodology. These analyses are conducted at global scale and, subsequently, at a regional scale, for a pioneer (Denmark) and a fast follower (Portugal). The comparison of the outcomes from the bibliometric and the technology growth analyses permits to understand the rhythm and order in which knowledge was created and applied in this particular innovation. It also provides a preliminary account of the interplay between pioneer and fast follower regions.
- The construction of a new technological innovation system in a follower country: wind energy in PortugalPublication . Bento, Nuno; Fontes, MargaridaThis article analyzes the process of construction of a new innovation system based on wind energy in a "follower" context. The technological innovation systems framework is used to analyze and explain the emergence of a new wind industry in Portugal, where this renewable energy technology knew a spectacular development in the past decade. This framework highlights the main processes or functions that intervene in the diffusion of a new technology. The evidence obtained demonstrates that the fulfillment of these functions, which were mostly studied in the context of pioneer countries, is still pertinent to explain the formation of a wind energy system in this follower country. Yet the type of resources and the nature of the activities needed to adopt the technology in the latter will often differ. This case provides new insights about the importance of functions that enhance the follower's capacity to assimilate the new technology (e.g. local knowledge development, experimentation), creating conditions for a fast move as soon as innovations become sufficiently mature in the core.
- Impact of weather regimes on the wind power ramp forecastPublication . Couto, António; Costa, Paula Silva; Rodrigues, L.; Lopes, Vitor V.; Estanqueiro, AnaThe stochastic nature of wind and the continuous need to balance electric generation with demand poses serious challenges to the power system operators. The impact of large wind integration into the power system is mitigated by decreasing the uncertainty associated with wind forecasts. In particular, the forecast of severe wind power ramps is important due to its impact on the energy market and grid operation and planning. This study proposes to classify the weather regimes over continental Portugal associated with the severe wind power production ramps. Thus, an automated classification system is developed by combining principal components analysis and kmeans clustering to find the most representative atmospheric flow patterns near the surface. This system can tackle with the synoptic spatial variability allowing the decrease of phase and timing mismatches present in single time forecasts. Then, the patterns are linked to the wind power production. Results show that it is possible to associate weather regimes with different levels of wind power production and identify certain atmospheric circulations with a higher chance to trigger severe wind power ramps.
- Wind and solar curtailmentPublication . Lew, Debra; Bird, Lori; Milligan, Michael; Speer, Bethany; Wang, Xi; Carlini, Enrico Maria; Estanqueiro, Ana; Flynn, Damian; Gomez-Lázaro, E.; Holttinen, Hannele; Menemenlis, Nickie; Orths, Antje; Smith, J. Charles; Soder, Lennart; Sorensen, Poul; Altiparmakis, Argyrios; Yoh, YasudaHigh penetrations of wind and solar generation on power systems are resulting in increasing curtailment. Wind and solar integration studies predict increased curtailment as penetration levels grow. This paper examines experiences with curtailment on bulk power systems internationally. It discusses how much curtailment is occurring, how it is occurring, why it is occurring, and what is being done to reduce curtailment. This summary is produced as part of the International Energy Agency Wind Task 25 on Design and Operation of Power Systems with Large Amounts of Wind Power.
- Summary of experiences and studies for wind integration: IEA Wind Task 25Publication . Holttinen, Hannele; Robitaille, André; Orths, Antje; Pineda, Ivan; Lange, Bernhard; Carlini, Enrico Maria; O’Malley, Mark; Dillon, Jody; Tande, John Olav; Estanqueiro, Ana; Gomez-Lázaro, E.; Soder, Lennart; Milligan, Michael; Smith, J. CharlesIEA WIND R&D Task 25 on “Design and Operation of Power Systems with Large Amounts of Wind Power” collects and shares information on wind generation impacts on power systems, with analyses and guidelines on methodologies. This paper summarizes the main results from the report published on January 2013 describing experience of wind integration as well as the most relevant wind power grid integration studies in the 15 participating countries. The studies build on the already significant experience in integrating wind power in power systems addressing concerns about the impact of wind power’s variability and uncertainty on power system security of supply and costs as well as grid reinforcement needs. The mitigation of wind power impacts includes more flexible operational methods, incentivising flexibility in other generating plants, increasing interconnection to neighbouring regions, and application of demand-side flexibility. Electricity storage is still not as cost effective in larger power systems as other means of flexibility, but is already seeing initial applications in places with limited transmission.