An evaluation study for improving gap flow simulations in coastal areas on Portugal

Winds inferred by Synthetic Aperture Radar (SAR) satellites are a very important source of spatial wind field behavior along coastal areas particularly on small coastal areas that are temporary affected by strong flow disturbances mainly driven from land to the ocean. Gap flow circulations, among others, are an example of such wind phenomena disturbances which are not yet described by regional atmospheric models nor by CFD modeling. Such situations could compromise both offshore wind resource and park deployment studies on places affected by the presence of these phenomena types. A possible way to overcome this situation is the usage of SAR images assimilated into regional atmospheric models using certain type of assimilation techniques. In this work, a real case occurred in a coastal area in Portugal will be taken into account. A strong gap flow occurred during the beginning of the night 9 December 2010 was captured by a SAR image which was assimilated into the model. Some validation meteorological stations were used for validation purposes taken into account scenarios performed with and without wind SAR assimilation. Spatial results lead to the conclusion that the assimilation of SAR images improves the wind pattern results which reflects how SAR assimilation into the mesoscale models are important for simulating the coastal wind flow patterns

Simulation of a-Si PV system linked to the grid by DC-DC boost and two-level converter

This paper is about a PV system linked to the electric grid by power electronic converters. The modeling for the converters emulates the association of a DC-DC boost with a twolevel power inverter in order to follow the performance of a testing commercial inverter employed on an experimental system. It is used pulse width modulation by sliding mode control associated with space vector modulation for control the boost and the inverter. The PV system is described by the five parameters equivalent circuit and parameter identification is carried out. Maximum power point tracking is implemented by a P V procedure. Simulation studies are performed and a comparison with the testing experimental system is presented

High resolution forecasts of wind in rough orography and in coastal conditions

The 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.

MOS – “Model Output Statistics”– Aplicação da metodologia para correcção das previsões de vento obtidas para Portugal Continental

Ponencia presentada en: XXXI Jornadas Científicas de la AME y el XI Encuentro Hispano Luso de Meteorología celebrado en Sevilla, del 1 al 3 de marzo de 2010.Este trabalho foi realizado no âmbito do Projecto financiado pela FCT - PTDC/CTE-ATM/73607/2006: BRIEF – “Building Regional Ensemble Forecasts”

Cartografia de uso do solo à escala regional com recurso a análise orientada a objecto e segmentação multiresolução

As metodologias actuais de classificação de uso do solo variam não só nas técnicas utilizadas, como no tipo de dados tratados e, fundamentalmente, no tipo de abordagem utilizada para a caracterização do objecto . Contudo, é possível identificar as componentes comuns que derivam da evolução das diferentes metodologias utilizadas, essencialmente a partir dos anos 60. É neste contexto, que apresentamos uma abordagem alternativa de tratamento de imagens de satélite, com base numa nova unidade mínima de análise – o objecto. .info:eu-repo/semantics/publishedVersio

Cartografia de Uso e Ocupação do Solo: Classificação vectorial com redes neuronais orientadas para objecto

O aumento na resolução espacial dos satélites e o detalhe contido desse modo numa imagem trouxeram novos contornos à cartografia de uso e ocupação do solo, numa escala grande e com posterior (sub)divisão adicional da nomenclatura a ser utilizada. Entretanto, a classificação automática e/ou semiautomática ainda não fornece o detalhe desejado, principalmente nas áreas fundamentalmente heterogéneas, como se verifica nas áreas urbanas. Esta dificuldade não está somente ligada à complexidade geométrica/espacial destas áreas mas também à complexidade semântica das suas entidades físicas - isto é a identificação de algumas classes do uso não depende tanto das características físicas de seus objectos, mas das funções a elas atribuídas. As abordagens adoptadas, ao nível do pixel, apresentam as suas próprias dificuldades, porque trabalham sobretudo na área da resposta espectral presente na imagem, quando a diferenciação empírica destes mesmos objectos incorpora outros elementos inerentes à natureza física e social do objecto. Tentando resolver este problema, a detecção remota e os SIG estão a ser cada vez mais usados para desenvolver fontes úteis de informação. Mas o ambiente urbano, por causa de sua paisagem heterogénea e dinâmica, tem sido exigente à aplicabilidade destes métodos e tecnologias. Auspiciosamente, as inovações modernas nos dados, nas tecnologias, e nas teorias municiaram os cientistas e utilizadores com o conhecimento necessário para o estudo de áreas urbanas complexas.info:eu-repo/semantics/publishedVersio

State-of-the-art of design and operation of power systems with large amounts of wind power, summary of IEA Wind collaboration

An international forum for exchange of knowledge of power system impacts of wind power has been formed under the IEA Implementing Agreement on Wind Energy. The task “Design and Operation of Power Systems with Large Amounts of Wind Power” is analysing existing case studies from different power systems.There are a multitude of studies made and ongoing related to cost of wind integration. However, the results are not easy to compare. This paper summarises the results from 15 case studies

Wind and Solar Curtailment: International Experience and Practices

High 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