EOL - Artigos em revistas internacionais
Permanent URI for this collection
Browse
Browsing EOL - Artigos em revistas internacionais by Issue Date
Now showing 1 - 10 of 32
Results Per Page
Sort Options
- High resolution forecasts of wind in rough orography and in coastal conditionsPublication . Miranda, Pedro; Costa, Paula Silva; Antunes, C.; Ferreira, João P.; Valente, A.; Rodrigues, Álvaro; Estanqueiro, AnaThe increase of the share of wind energy in total electrical power requires the development of reliable forecasts of wind power at different time scales, from minutes to days, on a regional and national basis. That development is multidisciplinary, involving meteorological and engineering components. In the present stage, though, it is thought that for time scales beyond 3 hours, the largest improvements are expected from the meteorological side, if meteorological forecasts are able to deal with mesoscale flow. In this paper three case studies of mesoscale modeling are analyzed and compared against wind observations in sites selected for their high potential for wind energy. Two cases deal with flow in the Islands of Madeira and San Jorge (Azores), characterized by rough orography, where measurements were made at the top of elevated plateaus. In these two cases, the large scale flow is obtained from ECMWF analysis and the mesoscale flow is computed, for one summer and one winter month, with two mesoscale models at resolutions between 6 and 0.5 km. In the third case, one full year of simulationis Continental Portugal is performed at resolutions between 27 and 3km, using boundary conditions from the NCEP/NCAR reanalysis and the MM5 model. Results indicate the interest of high horizontal resolution for wind forecasts in complex terrain but also some difficulties in the representation of boundary layer effects in conditions of large thermal forcing.
- A Dynamic Wind Generation Model for Power Systems StudiesPublication . Estanqueiro, AnaIn this paper, a wind park dynamic model is presented together with a base methodology for its application to power system studies. This detailed wind generation model addresses the wind turbine components and phenomena more relevant to characterize the power quality of a grid connected wind park, as well as the wind park response to the grid fast perturbations, e.g., low voltage ride through fault. The developed model was applied to the operating conditions of the selected sets of wind turbine experimental benchmark data from Azores and Alsvik wind parks, both for steady and transient operation of the grid. The results show a fairly good agreement in the relevant range of frequencies and indicate the model may be used as a tool for power system studies.
- How to Prepare a Power System for 15% Wind Energy Penetration: the Portuguese Case StudyPublication . Estanqueiro, Ana; Castro, Rui; Flores, Pedro; Ricardo, João; Pinto, Medeiro; Rodrigues, Reis; Lopes, J. PeçasThe 2001/77/CE Renewable Energies European Directive together with Kyoto Protocol ratification supported by a government vision and strong objective on the reduction of external oil dependence put Portugal in the front line to achieve one of the highest wind energy penetrations within 10 years$1 (B time. This paper gives a summarized overview of the Portuguese technical approaches and methodologies followed in order to plan and accommodate the ambitious wind power goals to 2010/2013, preserving the overall quality of the power system.
- Design of a new urban wind turbine airfoil using a pressure-load inverse methodPublication . Henriques, J.C.C.; Silva, F. Marques da; Estanqueiro, Ana; Gato, L.M.C.This paper presents the design methodology of a new wind turbine airfoil that achieves high performance in urban environment by increasing the maximum lift. For this purpose, an inverse method was applied to obtain a new wind turbine blade section with constant pressure-load along the chord, at the design inlet angle. In comparison with conventional blade section designs, the new airfoil has increased maximum lift, reduced leading edge suction peak and controlled soft-stall behaviour, due to a reduction of the adverse pressure gradient on the suction side. Wind tunnel experimental results confirmed the computational results.
- Integração de sistemas de energia renovável a instalações residenciaisPublication . Marujo, R.; Simões, Teresa; Estanqueiro, AnaOs sistemas de microgeração domésticos que produzem energia a partir de fontes renováveis necessitam de legislação especifica e de ferramentas para identificar os potenciais e a viabilidade de implantação de soluções tecnológicas adaptadas ao ambiente urbano. Este artigo analisa exemplos de implementação de sistemas eólicos, fotovoltaicos e híbridos em uma edificação, debatendo questões económicas e energéticas.
- Integração de Sistemas de Energia Renovável a Instalações ResidenciaisPublication . Marujo, R.; Simões, Teresa; Estanqueiro, AnaOs sistemas de microgeração domésticos que produzem energia a partir de fontes renováveis necessitam de legislação especifica e de ferramentas para identificar os potenciais e a viabilidade de implantação de soluções tecnológicas adaptadas ao ambiente urbano. Este artigo analisa exemplos de implementação de sistemas eólicos, fotovoltaicos e híbridos em uma edificação, debatendo questões económicas e energéticas.
- Impacts of large amounts of wind power on design and operation of power systems, results of IEA collaborationPublication . Holttinen, Hannele; Meibom, Peter; Orths, Antje; Lange, Bernhard; O'Malley, Mark; Tande, John O.; Estanqueiro, Ana; Gomez, Emilio; Soder, Lennart; Strabac, Goran; Smith, J. Charles; Van Hulle, FransThere are dozens of studies made and ongoing related to wind integration. However, the results are not easy to compare. IEA 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. In the state-of-the-art report (October, 2007), and the fi nal report of the 3 years period (July, 2009) the most relevant wind power grid integration studies have been analysed especially regarding methodologies and input data. Several issues that impact on the amount of wind power that can be integrated have been identifi ed. Large balancing areas and aggregation benefi ts of wide areas help in reducing the variability and forecast errors of wind power as well as help in pooling more cost effective balancing resources. System operation and functioning electricity markets at less than day-ahead time scales help reduce forecast errors of wind power. Transmission is the key to aggregation benefi ts, electricity markets and larger balancing areas. Best practices in wind integration studies are described. There is also benefi t when adding wind power to power systems: it reduces the total operating costs and emissions as wind replaces fossil fuels and this should be highlighted more in future studies.
- Currents of ChangesPublication . Holttinen, Hannele; Orths, Antje; Eriksen, Peter Børre; Hidalgo, Jorge; Estanqueiro, Ana; Groome, Frank; Coughlan, Yvonne; Neumann, Hendrik; Lange, Bernhard; Hulle, Frans van; Dudurych, IvanThe Power Systems in Denmark, Portugal, Spain, Ireland, and Germany have some of the highest wind penetrations in the world, as shown in Table 1. The management of the different power systems to date,with increasing amounts of wind energy, has been successful.There have been no reported incidents in which wind has directly or indirectly been a major factor causing operational problems on the system. In some areas with high wind penetration, however, the transmission system operator (TSO) had to increase remedial actions signifi cantly in order to decrease the loading of system assets during times of high wind power infeed. In some areas, the risk of faults may have increased. Higher targets for wind power will mean even higher penetration levels locally and high penetration levels in larger power systems. There are a number of issues that will require active management in the near future; in some cases, such management is needed today. In this article, the situations of five countries with high wind penetration are briefl y presented, with special emphasis given to their future needs with respect to accommodating targeted wind power amounts. The final section provides an overview of offshore grid developments and plans in Europe.
- Experience and challenges with short-term balancing in european systems with large share of wind powerPublication . Soder, Lennart; Abildgaard, Hans; Estanqueiro, Ana; Hamon, Camile; Holttinen, Hannele; Lannoye, E.; Gomez-Lázaro, E.; O'Malley, Mark; Zimmermann, UweThe amount of wind power in the world is quickly increasing. The background for this development is improved technology, decreased costs for the units, and increased concern regarding environmental problems of competing technologies such as fossil fuels. Some areas are starting to experience very high penetration levels of wind and there have been many instances when wind power has exceeded 50% of the electrical energy production in some balancing areas. The aims of this paper are to show the increased need for balancing, caused by wind power in the minutes to hourly time scale, and to show how this balancing has been performed in some systems when the wind share was higher than 50%. Experience has shown that this is possible, but that there are some challenges that have to be solved as the amount of wind power increases.
- Methodology to study the life cycle cost of floating offshore wind farmsPublication . Castro-Santos, Laura; Garcia, Geuffer; Diaz-Casas, VicenteThe main objective of this paper is to determine a theoretical methodology process to study the life cycle cost of floating offshore wind farms. The principal purpose is adapting the LCC (Life-Cycle Cost Calculation) from several authors to the offshore wind energy world, providing a new method which will be called LCSFOWF. In this sense, several general steps will be defined: life cycle definition, process breakdown structure, viability study and sensitivity study. Moreover, technical and economic issues and their relations will be considered. On the other hand, six life cycle phases needed to install a floating offshore wind farm will be defined: conception and definition, design and development, manufacturing, installation, exploitation and dismantling. They will be useful to define the majority of the steps in the process. This methodology could be considered to calculate the real cost of constructing floating offshore wind farms.