Can the load angle of a generator be calculated using a mathematical equation?

[Idea04]

Is there a mathematical equation for calculating the load angle of a generator?
I'm trying to calculate the real and reactive power of the generator which the equation I am using is
EV/Xd sin delta
where E is the generator excitation voltage
V is the generator terminal voltage
Xd is the generator reactance
and delta is the load angle of the of voltage E and V
Thanks in advance the the help

 

[gerbi]

Load angle is between stator and rotor fields (vectors). It is a function of power and excitation current, in general.
You can be calculate it from detailed mathematical model of machine (which is rather.. complicated). Otherwise, it can be estimated. See eq 1 and 2 in this paper:

http://www.google.pl/url?sa=t&rct=j...=TNzGap0SFzHkrM-_uYLY6A&bvm=bv.44770516,d.Yms

Now, it all depends how accurate this calculation needs to be. You can assume that Xq~Xd (quite accurate, use only for cylindrical generator).
If you want to know it's exact value.. Xq is not among standart parameters (provided by manufacturer, from my experience). You need a series of measurements to estimate it (or good knowledge + all design data to calculate it).

Ok, this was answer to your question. May I ask now what is the purpose of this calculation ? I suggest using other set of parameters to calculate power (forget about load angle). Why not using vectors -> stator current, stator voltage and power factor ?