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