Interpreting V Curves in Motor Operation: Excitation Current, Reactive Power & Capacitive Effects

I wonder how I should interpret the V curves for the motor. It seems simple enough for a generator:
at a constant value of voltage and frequency delivered to the network, we can issue a certain active power and, by regulating the excitation current, we also give back reactive power to the network - whether it is capacitive or inductive, it depends on the demand.
But how to interpret V curves for an engine? How do we increase the excitation current, do we get capacitive power from the network? So what, the motor becomes a capacitor? I do not understand.

This is how it transfers reactive power to the network, i.e. like a capacitor. There were even special machines just for this. Sometimes such a machine was quite large, but it had an obscenely thin shaft, because it was used to compensate for reactive power, the so-called compensators ...
https://pl.wikipedia.org/wiki/Kompensator_synchroniczny