I'm strugguling to understand why the current in this problem is I = 1pu. The problem is as follows:
An electric generator is rated for 20MVA, 13.8KV. It is a diesel engine driven, three phase, four-wire system. The generator is sailent pole with dampers. The manufacturer's data for reactances is:
X"d = 0.20, X'd = 0.30, Xd = 1.25, Xq = 0.90
Assume a terminal voltage of 1pu for a transient study conducted at rated power and voltage. The power factor is 1.0. What magnitude of generated voltage should be used for this study?
I know the following:
E'm = Vt - iX'dmI , where E'm = generated transient voltage
Vt = 1pu Xdm = 0.3 These where stated in the problem.
Not really sure why I = 1pu. I guess it must have come from Vt being 1pu and the study being conducted at rated voltage and power.
Some explanation behind this would be appreciated.
Thanks in advance
