Aurland I, Norway

Successful acceptance tests for a new class of high-performance runner

Beginning of October, the model acceptance tests for the rehabilitation of the existing turbines at HPP Aurland I were successfully completed. The fully homologous model tests have been witnessed in the ANDRITZ Pelton hydraulic Laboratory (Vevey, Switzerland) with the online participation by representatives from the customer Hafslund E-CO and Norconsult with the local consulting by Etaeval.

© ANDRITZ

The entire Aurland power plant complex in Norway encompasses five hydropower plants in the Aurlandsvassdraget, Aurland municipality, Vestland. The three Pelton turbines of Aurland I are utilizing a head of 840 meters down to Vassbygdvatnet from the main intake reservoir Viddalsmagasinet (930-868 meters above sea level). With a total capacity of 849 MW and an annual energy production of 2,297GWh, the hydropower plant is one of the largest in Norway. The two first units were commissioned in 1973 and 1975 and the third in 1989. Back in 1970’s when they originally were built, the Pelton turbines were the largest of their kind in the world. The main driver to change the existing runners - delivered between 2004 and 2006 by a different supplier - after only 15 years is related to improved efficiency, according to Hafslund E-CO. The client considers that “the technology development in the Pelton market, generally, has been very good in the last 15 years”. In addition the client experienced severe cracks on the existing runners - the first in 2016 and the last just after signing this contract in 2019.

The challenges for the Aurland I project were the high-performance guarantees for the three 6-jet, high-head Pelton turbines. The existing and maintained components such as manifold and casing constituted challenges for the development of a high-performance runner since the prevailing hydraulics no longer corresponded to state-of-the-art-technology. The developments by ANDRITZ over the last two years on similar (high-head, >800m, six-jet) projects enabled the evolution of a new class of high-performance runners for up to 1,100m net head. Especially the integration of such a runner combined with new nozzles into an existing hydropower unit presents challenges to the hydraulic design which must be analyzed with care. Today, In-house developed CFD enables ANDRITZ to optimize the hydraulic designs prior to model tests. The interplay and feedback-loop between CFD optimization and detail analysis of the model characteristics in the laboratory is essential to achieve high performances on rehabilitation projects.

With this project ANDRITZ with its specialists for Pelton turbines proves once more its leading position in the turbine technology market.

© ANDRITZ
© ANDRITZ

TECHNICAL DATA

Total output: 849 MW 
Scope: 3 x 283 MW / 3 x 300 MVA
Head: 840 m
Speed: 375 rpm
Diameter: 4,014 mm

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