Abstract

To gain stable operation of a hydro power plant, it is mostly a matter of having the right ratio between the time constant of the rotating masses, Ta, and the time constant for the water masses, Tw. If Ta/Tw> 6 (or at least >4), the stability is normally not a problem. However, for power plants with long penstocks, this criterion is not enough. The elastic property of the penstock becomes an issue. The solution of the wave equation includes a term, which mathematically is defined as tanh (tangents hyperbolicus). This function is notoriously unstable. It has a similarity to the tan-function, which goes from to ±∞ as it approaches ± 90°. The cross frequency defines the frequency up to which the governor will function. Above the cross frequency, any disturbance will go without any interference from the governor. Therefore, the issue is to make sure that the elastic frequency is well above the cross frequency. In this paper, the transfer functions are solved analytically and the pressure response calculation is partly verified by measurements. However, the quality of the measurements are not quite adequate and will be repeated this spring.

Details

Title
The elastic property of water and penstock’s effect on the governor stability
Author
Nielsen, T K 1 ; Svingen, B 2 ; Vilberg, I K 3 

 Department of Energy and Process Engineering, Waterpower Laboratory, NTNU, Norway 
 Department of Energy and Process Engineering, Waterpower Laboratory, NTNU, Norway; Hymatek Controls AS, Oslo, Norway 
 Department of Energy and Process Engineering, Waterpower Laboratory, NTNU, Norway; Flow Design Bureau AS, Stavanger, Norway 
Publication year
2019
Publication date
Mar 2019
Publisher
IOP Publishing
ISSN
17551307
e-ISSN
17551315
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2557595031
Copyright
© 2019. This work is published under http://creativecommons.org/licenses/by/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.