Vattenfall

About: Vattenfall is a company organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Wind power & Combustion. The organization has 685 authors who have published 857 publications receiving 18912 citations. The organization is also known as: Vattenfall AB & Kungliga Vattenfallstyrelsen.

Wind Turbine Structural Health Monitoring: A Short Investigation Based on SCADA Data

Abstract: The use of offshore wind farms has been growing in recent years, as steadier and higher wind speeds can be generally found over water compared to land. Moreover, as human activities tend to complicate the construction of land wind farms, offshore locations, which can be found more easily near densely populated areas, can be seen as an attractive choice. However, the cost of an offshore wind farm is relatively high, and therefore their reliability is crucial if they ever need to be fully integrated into the energy arena. As wind turbines have become more complex, efficient, and expensive structures, they require more sophisticated monitoring systems, especially in offshore sites where the financial losses due to failure could be substantial. This paper presents the preliminary analysis of supervisor control and data acquisition (SCADA) extracts from the Lillgrund wind farm for the purposes of structural health monitoring. A machine learning approach is applied in order to produce individual power curves, and then predict measurements of the power produced of each wind turbine from the measurements of the other wind turbines in the farm. A comparison between neural network and Gaussian process regression is also made.

Numerical Predictions of Bubbly Two-Phase Flows with OpenFOAM:

Abstract: A new model for simulation of bubbly two-phase flows has been developed and implemented into an open-source Computational Fluid Dynamics (CFD) code OpenFOAM. The model employs the two-fluid framework with closure relationships for the interfacial momentum transfer. The bubble size is calculated based on the solution of the transport equation of the interfacial area concentration. The predictions are validated against selected data obtained in the DEDALE experiment and containing the measured void fraction, the phasic velocities and the interfacial area concentration. In general, good agreement between calculated and measured data is demonstrated; however, the relative phasic velocity is systematically over-predicted. The levels of void fraction and the observed wall void peaking are well captured in the calculations.

Method and device for generation of mechanical work and, if desired, heat in an evaporative gas turbine process

Abstract: The invention refers to a method and a device for generation of mechanical work and, if desired, heat in an evaporative gas turbine process, comprising compression of air in at least one stage, transport of said air with water to a combustion chamber for combustion together with fuel and discharge of the combustion exhaust gases to a gas turbine following thereto for generation of mechanical work and heat, if desired, of the compressed air only a partial flow being humidified by addition of water while the rest of the air flow being carried to the combustion chamber without passing through the humidifier. The invention suggests that the partial air flow to be humidified constitutes less than half of the total flow of compressed air and is subjected to a high-rate humidification to a moisture content of above 0.3 kgms water per kgms dry air.