▁controls , ▁generator , ▁supporting ▁structure ▁and ▁foundation . ▁Further ▁design ▁questions ▁arise ▁when ▁integr ating ▁wind ▁tur b ines ▁into ▁elect rical ▁power ▁gr ids . ▁ ▁Aer od ynam ics ▁▁ ▁The ▁shape ▁and ▁dimensions ▁of ▁the ▁bl ades ▁of ▁the ▁wind ▁tur bine ▁are ▁determined ▁by ▁the ▁aer od ynamic ▁performance ▁required ▁to ▁efficiently ▁extract ▁energy ▁from ▁the ▁wind , ▁and ▁by ▁the ▁strength ▁required ▁to ▁resist ▁the ▁forces ▁on ▁the ▁bla de . ▁▁▁ ▁The ▁aer od ynam ics ▁of ▁a ▁horizontal - axis ▁wind ▁tur bine ▁are ▁not ▁straightforward . ▁The ▁air ▁flow ▁at ▁the ▁bl ades ▁is ▁not ▁the ▁same ▁as ▁the ▁air flow ▁far ▁away ▁from ▁the ▁tur bine . ▁The ▁very ▁nature ▁of ▁the ▁way ▁in ▁which ▁energy ▁is ▁extracted ▁from ▁the ▁air ▁also ▁causes ▁air ▁to ▁be ▁def lect ed ▁by ▁the ▁tur bine . ▁In ▁addition ▁the ▁aer od ynam ics ▁of ▁a ▁wind ▁tur bine ▁at ▁the ▁rot or ▁surface ▁exhib it ▁phen omena ▁that ▁are ▁rarely ▁seen ▁in ▁other ▁aer od ynamic ▁fields . ▁ ▁Power ▁control ▁▁ ▁The ▁speed ▁at ▁which ▁ ▁a ▁wind ▁tur bine ▁rot ates ▁must ▁be ▁controlled ▁for ▁efficient ▁power ▁generation ▁and ▁to ▁keep ▁the ▁tur bine ▁components ▁within ▁designed ▁speed ▁and ▁tor que ▁limits . ▁ ▁The ▁cent rif ug al ▁force ▁on ▁the ▁spin ning ▁bl ades ▁increases ▁as ▁the ▁square ▁of ▁the ▁rotation ▁speed , ▁which ▁makes ▁this ▁structure ▁sensitive ▁to ▁o vers pe ed . ▁Because ▁the ▁power ▁of ▁the ▁wind ▁increases