Power generation package (PGP)

A question about PGP. If I synchronized the PGP output power to the bus bar with two other incomers from external source. If the two incomers fails could the PGP still work and supply the switchboards and the grid? The PGP output 3MW to15MW.
Insufficient information. Does the "PGP" (should describe the PGP clearly) have Isochronous Speed Control governor mode? Do the three units receive some kind of load signal from a "remote" source?

What is the load being supplied? Does it exceed 15 MW?

Also we weren't told what the "switchboards" are and where they receive their power source for operation come from.

Simply too little information supplied.

The answer--based on the information provided--is no.