Reverse Reactive Power

Your premises are incorrect, and your thinking about the problem foggy at best. Let's review: in any network, and the power distribution network is such, there are imbalances.

If your local generator working against the network is in phase and produces higher voltage, it is a net energy supplier. If its voltage is lower, it is a net energy consumer.

If your local generator voltage is equal that of the net, leading phase produces current when the net does not = inductive virtual power. Lagging phase = capacitive virtual power.

Since most loads are resistive and inductive, a corrective balancing is frequently required by the energy producer. They charge extra for the customer for their trouble, producing the necessary, mostly capacitive correction using their power generators.

I repeat, reactive power is NORMAL for a generator. Your generators working against each other is not. Fix their phase relationships, and they and you will be a happy camper.

Assuming you do not have a mains connection, it looks as if Gen2 voltage is going high and taking all the reactive power and more. If sudden event correcting itself, may be loss of AVR reference or AVR fault. Monitor field current of Gen 2 with DC meter and see if it jumps high when turbines go reverse. High field current increases lagging output of a generator if bus voltage stays normal.