In continuation of the above:
Suppose a situation when plant total load is 20 MW with following distribution: GT1 (Isochronous mode)=4 MW, GT2 (Droop mode)= 8 MW, GT3 (Droop mode)=8 MW and without any gas turbine tripping, a big block of load like 8 MW is shed (for example, due to a feeder tripping). What would be the response of Isochronous machine in this case? Will it go into reverse power in an attempt to maintain bus frequency? Please keep in mind that there is no communication link between the three turbines for load sharing and the power house is in island mode (i.e., not connected with public utility).