Assuming that the synchronous machine is connected to and running on the grid (synchronized), what needs to be changed i

[answerhappygod]

Assuming that the synchronous machine is connected to and
running on the grid (synchronized), what needs to be changed in
order to cause the machine to draw power from the grid (to acts as
a load) or to deliver power to the grid (to act like a source)?
p/s: please answer the question correctly and in a simple way to
understand