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.

Large Eddy Simulation of Natural Convection Boundary Layer on a Vertical Cylinder

Abstract: Large eddy simulation of natural convection boundary layer along a constant temperature vertical cylinder is studied and the results are compared with the existing experimental data. The highest local Grashof number is Grz = 5 × 1011. It is shown that although there are some discrepancies between the results in the region close to the wall, there is qualitative agreement between them. In order to verify the credibility of the simulations, cross correlation of Reynolds stresses is studied and interpreted.

Long-term Experience with Maleic Acid in a Hard Coal-fired FGD Unit

Abstract: The addition of adipic acid to increase the gas clean-ing efficiency of lime water in brown coal power plants is the state-of-the-art approach. In hard coal power plants, functional considerations mean that adipic acid is used less frequently. In Block 3 of the Nordjyllandsvaerket hard coal power plant, maleic acid was used over an 8-year period with great success, improving the desulphurisation capacity and simultaneously reducing operating costs. The greatest advantage of maleic acid as opposed to adipic acid is its exceptional biological stability in the flue gas desulphurising plant.

Forecasting cross-border power exchanges through an HVDC line using dynamic modelling

Abstract: As smart grids develop, power systems become more complex, and the role of data gain considerable importance for the reliability of power supply. Thus, data processing techniques have to be investigated and compared to increase the efficiency of asset management decisions. In this paper, we explore several black-box models in order to predict power exchanges through a high-voltage direct-current line between Sweden and Denmark, using publicly available data on loads and power prices. An auto-regressive moving average with external input model based on load data provides the most accurate forecasts according to mean square error and other selected criteria. This is the first step to build a more comprehensive model that will also include other technical data such as maintenance and unplanned outages, but also macroeconomic factors. The final goal is to provide network operators with a parsimonious sequential model composed of several modules giving accurate predictions that support efficient asset management decisions.

Equipment for uninterrupted power control of pumped storage plant (PSW) for network service, checks water balance in parent control and optimization of dual block, so that operator compensates impending shortages

Abstract: The equipment has hydraulic accumulator (3) provided at end of high pressure side impulse water line (2). The electrical connections of double block (32) relative to high-voltage network (29) are performed. The block is dimensioned in performance, so that same operating hours in turbine and pump modes are required and continuous provision of network services is made by 24 hours a day. The water balance is checked in parent control and optimization of block, so that operator compensates impending shortages caused by greater deviations between predicted and actual accusations. The output range from the minimum power output at the engine performance of pump storage sets (PSS) to the minimum input power of identical PSS by the hydraulic operating during simultaneous operation of a short-circuit PSS (30) in turbine operation is set, while the other PSS (31) in the pumping mode is muted. An independent claim is included for method for uninterrupted power control of pumped storage plant (PSW) for network service.