Analysis of hydraulic pressure transients in the waterways of hydropower stations
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Hydropower plants have the ability to go from a full load to no load in just a few
seconds. In order to go from full load to no load in a few seconds the flow is
controlled by movement of guide vanes. At fault detection the guide vanes closes
quickly for safety reasons. This causes hydraulic transients in the waterways, which
leads to a pressure rise in the spiral case and a pressure drop in the draft tube.
There have been a few accidents related to these quick closures of the guide vanes
where the runner blades break and entire power stations are damaged. These
incidents are caused by a full column separation in the draft tube. An early sign of a
full column separation is large cavities. The main objective of this degree project is to
analyse the effects of a quick closure of the guide vanes and to make a guide book of
how to find indications of large cavities when performing closure tests. Data taken
from commissioning and status tests for several turbines were analysed.
In conclusion, the guide book of how to find indications of large cavities will help
analyse the results of a quick closure of the guide vanes. Due to the unique
appearance of pressure transients for each power station this guide book will not be
enough for a complete analyse of a closing test. Although, it will help to notify when
there is a need for further analyses by expert personnel.
Place, publisher, year, edition, pages
2011. , 73 p.
UPTEC ES, ISSN 1650-8300 ; 11007
Hydropower, pressure transients, full column separation, large cavities, reverse waterhammer
Vattenkraft, trycktransienter, separation av vattenpelare, vattenslag, större kaviteter
IdentifiersURN: urn:nbn:se:uu:diva-152187OAI: oai:DiVA.org:uu-152187DiVA: diva2:412851
Lundin, UrbanPernestål, Kjell