An increase in excitation voltage would have no bearing on current drawn as this is only dependant on load characteristics.
An unexpected increase of output voltage due to loss of magnetic field between stator and rotor or engine speed fluctuation should be counteracted by the AVR (if one present) the only effect on current this would have is to increase the armature current whilst the actual KW output would decrease.
I may have misunderstood your post, is it a question from a paper you need explaining????
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