Analysis of the efficiency of wind turbine gearboxes using the temperature variable

The aim of this paper is to evaluate how lubricant selection affects gearbox efficiency and overall energy production by analysing real data from wind farms, monitored and controlled by a Supervisory Control and Data Acquisition (SCADA system). The turbines analysed worked with two or more oil types for the same amount of hours, which allowed to establish relations between the active power curves and wind velocity; oil temperature inside gearboxes and wind velocity; and oil temperature inside gearboxes and active power production. The results of this study evidenced a direct relation between oil characteristics and energy efficiency i.e. gearboxes working with mineral oil perform better then gearboxes working with synthetic oils. Those differences can be significant in terms of active power production. Also, it was observed oil degradation as function of temperature increase, with changes on viscosity, which reveals that temperature behaviour along the active power curve is strongly related to oil' characteristics. (C) 2018 Elsevier Ltd. All rights reserved.Agência financiadora Portuguese Foundation for Science and Technology (FCT) PTDC/AAG-TEC/1710/2014 MONITOR project - Atlantic Area EAPA_333/2016 Portuguese Foundation for Science and Technology under the Portuguese Researchers' Programme 2014 IF/00286/2014/CP1234 Marie Sklodowska-Curie Actions of the European Union's H2020-MSCA-IF-EF-RI-2016/under REA - 748747info:eu-repo/semantics/publishedVersionhttp://creativecommons.org/licenses/by/4.0

An evaluation of offshore wind power production by floatable systems: a case study from SW Portugal

The challenge for floating offshore wind structures is to reduce costs. The industry needs a wind turbine support solution that can be fabricated and deployed from existing shipyards and port facilities, while investors need accurate estimations and forecasts of wind resources and quantified information on the inherent variability in wind power generation. This paper merges hindcast model data with observed in situ data to characterize the wind resource potential off the SW coast of Portugal. The validation procedure adopted allows an estimation of the coefficient used for power-law extrapolation of the wind measurements and a reduction in the uncertainty of the power density calculations. Different types of turbine model are compared and site metocean characteristics are examined as a basis for choosing between existing wind floatable solutions. The calculations using four different wind turbine models indicate a preferable installed capacity of 3-4 MW for a hub height of 90-120 m (i.e., representing the best capacity factor and load hours). There is a consistent difference in power density of about 20% from a location 5 nautical miles (NM) offshore to one 10 NM offshore, which represents an increment of 20% -25% in energy production depending on the particular wind turbine capacity factor. (C) 2017 Elsevier Ltd. All rights reserved.Portuguese Foundation for Science and Technology [FCT - PTDC/AAG-TEC/1710/2014]Portuguese Foundation for Science and Technology under the Portuguese Researchers' Programme [IF/00286/2014/CP1234]Portuguese Foundation for Science and Technology Investigator Programme [IF/01142/2015

Estimating the optimum size of a tidal array at a multi-inlet system considering environmental and performance constraints

This paper investigates the optimum tidal energy converter array density at a tidal inlet by applying surrogate-based optimisation. The SBO procedure comprises problem formulation, design of experiments, numerical simulations, surrogate model construction and constrained optimisation. This study presents an example for the Faro-Olhão Inlet in the Ria Formosa (Portugal), a potential site for tidal in-stream energy extraction. A 35 kW Evopod™ floating tidal energy converter from Oceanflow Energy Ltd. has been used for array size calculations considering two design variables: (1) number of array rows, and (2) number of tidal energy converter per row. Arrays up to 13 rows with 6–11 tidal energy converters each are studied to assess their impacts on array performance, inlets discharges and bathymetry changes. The analysis identified the positive/negative feedbacks between the two design variables in real case complex flow fields under variable bathymetry and channel morphology. The non-uniformity of tidal currents along the array region causes the variability of the resource in each row, as well as makes it difficult to predict the resultant array configuration interactions. Four different multi-objective optimisation models are formulated subject to a set of performance and environmental constraints. Results from the optimisation models imply that the largest array size that meets the environmental constraints is made of 5 rows with 6 tidal energy converter each and an overall capacity factor of 11.6% resulting in an energy production of 1.01 GWh year−1. On the other hand, a higher energy production (1.20 GWh year−1) is achieved by an optimum array configuration, made of 3 rows with 10 tidal energy converters per row, which maximises power output satisfying environmental and performance restrictions. This optimal configuration permits a good level of energy extraction while having a reduced effect on the hydrodynamic functioning of the multi-inlet system. These results prove the suitability and the potential wide use of the surrogate-based optimisation method to define array characteristics that enhance power production and at the same time respect the environmental surrounding conditions.info:eu-repo/semantics/publishedVersio

Eduardo González-Gorbeña Eisenmann's Quick Files

The Quick Files feature was discontinued and it’s files were migrated into this Project on March 11, 2022. The file URL’s will still resolve properly, and the Quick Files logs are available in the Project’s Recent Activity

Energias limpas na Ria Formosa, o caminho da sustentabilidade

O crescimento económico e populacional está entre os fatores mais importantes para o aumento do consumo energético mundial. Atualmente, a forma de energia que o Homem mais utiliza é a energia química (cerca de 80%), nomeadamente, combustíveis fósseis, como o petróleo, o carvão e o gás natural. No entanto, essas fontes são muito poluentes, pois a sua utilização é responsável pela emissão de substâncias nocivas para o ambiente e para a saúde pública. Um exemplo disso, é o aumento da concentração de gases com efeito estufa na atmosfera, como o dióxido de carbono (CO2), que é uma das principais causas do aquecimento global. Além da emissão de poluentes, essas fontes de energia não são renováveis, o que significa que estão sendo consumidas a uma taxa mais rápida do que a necessária para sua produção e, portanto, a sua disponibilidade é limitada e diminuirá ao longo do tempoinfo:eu-repo/semantics/publishedVersio