Therefore, in the present example the dynamic contribution value and {TAIL ~ active power variation requirement} of each wind turbine is imposed by {HEAD ~ the grid operator}  
Therefore , in the present example the dynamic contribution value and { TAIL ~ active power variation requirement } of each wind turbine is imposed by { HEAD ~ the grid operator }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH