Generators in parallel with high current on Neutral

I have two generators 125kW that when they are in parallel and the power is perfectly shared with 60+60kW @PF=1 (resist load) I have 10Amps on neutral. When I unbalance the load (I want remove from grid one Generator) I saw current over 100Amps on neutral, and when the generator is close to have 0kW, current on neutral is over 300Amp.
What's the cause of this problem?

If you have 10kVAR, you have reactive power. Circulating currents have nothing to do with load power factor. Is there any kVAR when not shared?
1. Are both generator alternators the same? If not, check the winding pitch on each.
2. Do you have a CT on one phase connected to the AVR? are these on the same phase for each alternator? Is the CT polarity correct?
3. What type of AVR? What type of control setting, Voltage, PF, kVAR?

If it was a my one generator, I'd started from disabling any protection, then - checked, are there short winding, and an insulation quality, then - started all this in a low speed (with a power drill?) and checked voltages (maybe even disconnecting the neutral) - are they equal, if all OK, connected the neutral and checked all this again - by the way, could someone mix ends and beginnings of coils?
Then - tried to load all this with something equal with an active resistance (maybe boilers or irons?), increased a speed, and if all works predictable, started gradually return all protection/controlling circuits back, checking all this after each my action.


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