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.

Fireside corrosion and steamside oxidation of 9–12%Cr martensitic steels exposed for long term testing

Abstract: To obtain long term corrosion and steam oxidation data for the 9–12%Cr ferritic steels, test tube sections have been exposed in Amager 3 and Avedore 1 coal fired power plants in Denmark (formerly run by ENERGI E2). Thus direct comparisons can be made for T91 and T92 for the 9%Cr steels and X20CrMoV121 and HCM12 for the 12%Cr steels. The test tubes were welded in as part of the existing final superheaters in actual plants and exposure has been conducted over a ten year period (1994–2005). Compared to the older steel types, T92 and HCM12 utilise tungsten to improve their creep strength. From Avedore I testing, T91 and T92 can be compared for exposure times up to ∼48 000 h exposure. From Amager 3 testing, X20, HCM12 and T92 were tested; T92 has been exposed for up to 31 000 h and X20 and HCM12 have had 84 500 h exposure. Tube sections were removed for various exposure durations such that steamside oxidation and fireside corrosion could be investigated with respect to exposure time. The fireside corr...

Grid-forming control strategies for black start by offshore wind power plants

Abstract: . Large-scale integration of renewable energy sources with power-electronic converters is pushing the power system closer to its dynamic stability limit. This has increased the risk of wide-area blackouts. Thus, the changing generation profile in the power system necessitates the use of alternate sources of energy such as wind power plants, to provide black-start services in the future. However, this requires grid-forming and not the traditionally prevalent grid-following wind turbines. This paper introduces the general working principle of grid-forming control and examines four of such control schemes. To compare their performance, a simulation study has been carried out for the different stages of energization of onshore load by a high-voltage direct-current (HVDC)-connected wind power plant. Their transient behaviour during transformer inrush, converter pre-charging and de-blocking, and onshore block-load pickup has been compared and analysed qualitatively to highlight the advantages and disadvantages of each control strategy.