Generator pu reactance values 1

[wbd]

I am working on a project and reviewing some generator datasheets. These are for a pumped storage unit so the generators also operate as motors when pumping. I have not seen pu values this high.

X"d 0.292 pu
X'd 0.35
Xd 0.98

These are saturated values and are these normal for a pumped storage unit where it operates as both a generator and a motor?

 

[xnuke]

The Electrical Transmission and Distribution Reference Book (ABB/Westinghouse) gives ranges for salient-pole generators and motors (with dampers), which I'm assuming is your type of machine, at rated voltage:
0.13 < X''d < 0.32
0.20 < X'd < 0.50
0.60 < Xd (unsat) < 1.50
It also notes that high speed units tend to have low reactance and low speed units high reactance. I'd expect your machine to be low speed, since it is a hydro unit, so the values should be toward the middle to upper part of the ranges shown.

Looks like your values are about normal.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[edison123]

For multipolar machines like hydros, those values are normal. The short circuit ratios for hydro machines are more than 1 and for cylindrical rotor machines, it is less than 1.

Muthu

http://www.edison.co.in

 

[bacon4life]

Also check that these values are on generator base. Often data gets converted to a 100 MVA base for modeling software.