Provided that {HEAD ~ the frequency} measured by the wind turbine falls within {TAIL ~ a certain admissible reference frequency range} , the active power generated will not be modified 
falls within
Provided that { HEAD ~ the frequency } measured by the wind turbine falls within { TAIL ~ a certain admissible reference frequency range } , the active power generated will not be modified
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH