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