On the load demand changing, {HEAD ~ the controller} signals the frequency converter to give {TAIL ~ a changed new power output} to meet the changed demand 
On the load demand changing , { HEAD ~ the controller } signals the frequency converter to give { TAIL ~ a changed new power output } to meet the changed demand
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH