Int ern at i onal  Journ al of  P ower E le ctr on i cs a n d  Drive  S ystem s   ( IJ PEDS )   Vo l.   12 ,  No.   3 ,  Septem be r 2021 , pp.  187 2 ~ 18 79   IS S N:  20 88 - 8694 ,  DOI: 10 .11 591/ ij peds . v12.i 3 . pp 187 2 - 18 79          1872       Journ al h om e page :  http: // ij pe ds .i aescore.c om   Compari son   of   roughness   index   f or   K itka   and   K oznica   wind   farms       Bukuri je   Ho x ha ,   Be dri   Dragusha   Univer sity   of   Pri shtina   “Ha san   Pr ishti na”,   Fa culty   of   Me cha ni ca l   Engi ne eri ng ,   Pri stina ,  Kos ovo       Art ic le   In f o     ABSTR A CT   Art ic le   hist or y:   Re cei ved   M a y   9 ,   20 21   Re vised   Ju l   8 ,   2 021   Accepte d   J ul   2 3,   20 21       Kos ovo   has   lim it ed   ren ewa bl e   ene rgy   resourc e s   and   its   pow er   gen era t ion   sec tor   is   b ase d   on   foss il   fue ls.   Su ch   a   situ ation   e mpha siz es   the   i mport an ce   of   ac t ive   r ese ar ch   a nd   eff icien t   use   of   ren ewa b le   en erg y   pote n tial.   Acc ording   to   the   an al ysis   of   me t eor ological   dat a   for   Kos ov o,   it   can   be   co ncl uded   tha t   am ong   th e   most   at tr ac t ive   pot enti al   wind   power   si te s   are   the   lo cati ons   known   as   Kitka   (42°   29 '   41"   N   and   21°   36'   45"   E)   and   Koznic a   (42°   39 ′   32″   N,   21°   22′30″ E) .   The   two   te rr ai ns   in   which   the   an al ysis   was   c arr ie d   ou t   a re   mount ai n   ar ea s,   with   altit ud es   of   1142   m   (Ki tka )   and   1230   m   (K ozni c a).   the   same   measuring   he ight ,   about   84   m   abov e   the   g round,   is   obt ai n ed   for   th ese   ave rag e   wind   s pee ds:   Ki tka   6, 667   m/s   and   Koznica   6 , 16   m/ s .   Sinc e   the   diffe ren ce   in   wi nd   spee d   is   quite   la rg e   ver sus   a   diffe ren ce   in   a lt i tude   th at   is   not   b ei ng   ver y   l arg e,   ana lys es   ar e   ma de   r ega rd in g   th e   te rr ai n   ch a rac t eri sti cs   inc ludi ng   the   t er rai n   relief   fe at ur es.   In   thi s   p ape r   it   wi ll   be   studi ed   how   muc h   the   roughne ss   of   th e   terrai n   inf lue nc es   the   out put   ene rgy .   Also,   that   the   assumpti on   to   be   ta k en   th e   sam e   as   to   how   muc h   the y   wil l   aff ect   the   annu al   ene rgy   produ ce d .   Ke yw or d s :   Energ y   yield   M ou ntain   Roug hn es s   Win d   directi on   Win d   s pee d   This   is   an   open   acc ess   arti cl e   un der   the   CC   BY - SA   l ic ense .     Corres pond in g   Aut h or :   Be dr i   Dr a gusha   Dep a rteme nt   of   M echa nical   E ng i neer i ng   Un i ver sit y   of   P rishtina   “ Hasa n   P rishtina” ,   P r ist ina ,  K osovo   Emai l:   bedri.m .drag usha@ uni - pr.e du       1.   INTROD U CTION   Be cause   of   t he   harmf ul   co ns e qu e nces   of   pol luti on   from   t he   emissi ons   of   var i ous   ga ses,   ren e wa ble   energ y   s ources   incr easi ngly   ga in   in   im porta nce.   T he   wind   is   a   natu ral   phenomen on   rela te d   to   the   m ov ement   of   ai r   pas ses   c ause d   pri maril y   by   dif fer e ntial   so la r   heati ng   of   the   earth' s   su r face   [1 ] ,   [2 ].   E uro pean   c ount ries   by   an   a gr e eme nt   hav e   decide d   to   s uppl y   20   pe rce nt   of   its   total   ene rgy   de man d   from   re new a ble   sourc es   by   2020.   We   a re   now   one   yea r   after   that   a gr ee ment,   a nd   we   can   see   how   fa r   K osovo   has   c om e   in   achie vi ng   t his   go al .   T his   go al   has   bee n   ac hi eved   by   co ns i der i ng   bi om as s   as   it   is   not   w idely   us e d   for   heati ng   need s ,   wh il e   oth e r   ren e wa ble   sou rces   rema in   la r gely   in   the   sha de .   T he   pote ntial   is   for   al l   resou rces,   but   le gal   re gu l at ions   hav e   bee n   a ble   to   dev el op   to   a   li mit ed   e xte nt .   In   two   yea rs   ( 2008   an d   2009),   m ore   t han   24, 000   MW   of   ne w   powe r   ca pacit y   base d   on   wi nd   e nerg y   was   instal le d   in   the   EU   c ount ries   [ 1].   N ow a da ys,   wind   ene r gy,   as   an   al te rn at ive   cl ean   sust ai nab le   energ y   sour ce,   has   bee n   recogn iz e d   as   one   of   the   fastest   de velo ping   re ne wab l e   energ y   s ource   te chnolo gies.   Win d   powe r   ge ner at io n   has   made   a   re mar ka ble   co ntri bu ti on   to   daily   li fe   acr oss   the   globe   a nd   has   gro w n   rap i dly   ove r   the   pa st   20   yea rs   [ 3 ].   As   a   re new a ble   e nerg y   s ou rce   with   t he   hi gh e st   grow t h   rate   in   the   la st   two   decad e s,   wind   ene rgy   is   co ns ide red   a   very   im portant   re so urce   of   el ec tric it y   pro du ct io n   in   the   fu t ur e .   T he   f or ecast s   for   t he   de velo pm e nt   of   wi nd   e ne rgy   a re   hi gh l y   opti mist ic   an d   sta te   that   this   typ e   of   e nerg y   will   be   imp or ta nt   in   the   f uture   [ 4] ,   [5 ].   Win d   t urbines   operat e   at   al titud e,   a nd   it   is   Evaluation Warning : The document was created with Spire.PDF for Python.
In t J  P ow Elec   & Dri S ys t   IS S N: 20 88 - 8 694       Compari son  of  rough ness  i nd ex for  Ki tk a  an d  K oz nic a   wi nd fa rms   ( B uk uri je  H ox ha )   1873   importa nt   to   know   w hat   ha ppens   to   ai r   densi ty   as   al ti tud e   i ncr ease s.   T he   densi ty   of   ai r   va ries   with   al ti t ud e ,   so   it   is   a   decr ea sing   functi on.   So   a bove ,   the   ai r   is   li gh te r.   T his   al lows   le ss   aerod ynamic s   to   be   c reated   sp onta neously   [ 6] ,   [7 ].     The   pr ima r y   mete orolo gical   facto r   in   eval uating   a   pros pe ct ive   wind   t urbi ne   sit e   is   the   mean   wi nd   sp ee d.   Anothe r   imp ort ant   pa rameter   is   t he   antic ipate d   e xtreme   wind   s peed   [ 8 ] ,   [ 9 ].   Win d   power   plants   gen e rate   el ect r ic it y   w hen   the   wind   is   bl ow i ng,   an d   t he   plan t   outp ut   dep e nds   on   t he   wind   sp ee d.   Win d   s peeds   cannot   be   pre dicte d   with   hi gh   acc uracy   over   daily   per i ods,   a nd   the   wind   oft en   fluct uates   f rom   mi nu te   to   minu te   a nd   ho ur   to   an   ho ur   [ 10] ,   [11 ].   In   fa ct ,   the   wind   al s o   va ries   eve ry   seco nd   due   to   tur bule nce   ca use d   by   la nd   feat ur es ,   t hermal   s ources ,   a nd   s pecific   weathe r   c ondit ion s .   It   al s o   bl ow s   more   strongl y   highe r   a bove   the   gro und   t han   cl os er   to   it,   due   to   s urface   fr ic ti on   [12 ] ,   [13 ].   Total   energ y   pro duct ion   a nd   capaci ty   fact or   are   fun dame nt al   aspects   of   a   wind   powe r   project .   To   determi ne   t he   op ti m um   e nergy   ou t pu t,   it   is   esse ntial   to   sel ect   the   rig ht   tur bin e   desig n   f or   a   l ocati on   [ 14 ].   Win d   t urbine   op e rati on   is   de pende nt   on   w ind   sp ee ds   to   gen e rate   powe r   [ 15 ].   S us ta in abili ty   eval uation   of   wind   re sour ce s   can   be   pe rfo rme d   us in g   dif fer e nt   ap proac hes   th at   are   c ompleme nta ry   betwee n   eac h   oth e r:   therm o - ec onomi c   an al ys is   (e nerg y   a nd/or   e xerg y   cal c ulati on s ),   li fe   cycle   assess ment   ( w hich   is   a   m ulti crit eria   pro du ct - ori ent ed   a nalysis ),   emer gy   ap pro ach   (a   ho li sti c   ap proac h   dono r   side   ori e nted ).   T hese   diff e re nt   assessme nt   ap proac hes   we re   c ompare d   one   by   one   an d/or   c ombine d   [1 6 ],   [ 17 ].   Ann ual   e nerg y   pr oduce d   is   ty pical ly   cal c ulate d   ref e rr i ng   to   the   a nnual   me an   wind   s peed   of   the   sit e.   Unfortu natel y,   the   a nnual   av erag e   wind   spe ed   va ries   sig nificantl y   [1 8 ].   Op e rati on   of   the   in div i du al   wi nd   tur bin es   ma y   be   ad ve rsely   im pacted   by   the   tur bule nt   wa kes   f rom   oth e r   up wind   t urbines ,   with   t he   mag ni tud e   of   the   im pact   dep e ndin g   la rgel y   on   the   t urb ines’   res pecti ve   r otor   siz es   a nd   distance   bet ween   one   a no t her,   as   well   as   on   the   ov e rall   sh a pe   of   t he   wi nd   fa rm   a nd   t urbine   sp aci ng   th erei n   [1 9 ].   Wi nd   s hear   in   ope n   gro und   wh e n   deali ng   with   distances   e . g .,   10m   in   it   hav e   a   gr ea te r   ef fect   tha n   w hat   is   found   in   the   fiel d.   N ow   increasin g   the   heig ht   t hese   do   not   ha ve   high   im pact.   T his   ef fect,   ho wever,   has   t he   e ffec t   of   re du ci ng   t he   energ y   ge ner at ed   by   a   tu rb i ne ,   an d   the n   the   entire   wi nd   fa rm   [ 20] ,   [ 2 1 ].   The   el ect rici ty   factor   pro duc ed   by   wind   e nerg y   ra ng e s   f r om   20   to   40% ,   in   gen e ral   [ 22],   [23 ].   The   value   of   t he   ca pacit y   fac tor   for   wind   t urbi nes   in   K oso vo   is   e sti mate d   to   be   25%   [ 24 ].   Ba s ed   on   the   anal ys is   done,   we   can   asse ss   pr e ci sel y   w hethe r   these   two   places   ha ve   the   po te ntial   to   co ntri bu te   to   the   local   ene rgy   pro du ct io n .       2.   RESEA R CH   METHO D   The   met hodol ogy   us e d   in   t hi s   pa per   c onsist s   of   co nsult ing,   stu dy i ng,   a na lyzing,   a nd   co mp a rin g   the   data   for   wind   sp ee d,   wind   di recti on   a nd   the   main   c ompon ents   to   a nalyze   the   r oughne ss   in   t hose   te r rai ns .   In   this   case   the re   are   us ed   one   yea r   meas ur e ment   f or   two   wind   farms,   K it ka   an d   K oz ni ca.   T his   met hod   of   analysis   is   si m ple,   a nd   we   a ss um e   or   hy po t he siz e   that:   in   our   ca se   we   are   deali ng   with   two   m ountain   t err ai ns,   we   ha ve   t he   sa me   wind   direc ti on ,   an d   their   geog raphical   c oor din at es   ( Koznica:   N   42.59 880° ;   E   21. 35468° ,   K i t k a   N   4 2 . 3 9 5 6 °   E   2 1 . 3 9 3 6 ° )   a r e   v e r y   c l o s e   so   we   w i l l   e x p e c t   to   h a v e   r e s u l t s   s a m e   to   t h e   e f f e c t   of   r o u g h n e s s .       2.1.    Site   descr iption   and   d at a’ s   f or   K oz nica   The   WPP   K oz nica   is   in   K oso vo,   ap pro ximat el y   16   km   s ou t h - east   of   Pr ist ina   an d   7   km   w est   of   Nov o   Brdo.   F or   the   a nalysis   of   wi nd   cha racteri sti cs   an d   wi nd   e nergy   po te ntial   of   the   Ko z nica   sit e,   the   me asu re ment   data   for   t he   one - yea r   pe rio d   01/0 5/2015   –   30/04 /2 016   hav e   been   us e d.   The   tur bi nes   pr e se nted   in   Ta ble   1,   ar e   not   l o c a t e d   at   t h e   s a m e   d i s t a n c e s ,   due   to   t h e   u n s u i t a b l e   t e r r a i n ,   b u t   t h e   p l a c e m e n t   w a s   d o n e   u s i n g   W A s P   s o f t w a r e .       Table   1.   Det ai ls   of   al l   tu rb i ne s   place d   in   K oz nica   Turb in e   no.   Co o rdin ate   of   tu rbin e   p lacem en t   Level   ab o v e   sea   (m)   X(m)   Y(m)   "T 1 "   5 2 9 0 8 7   4 7 1 6 2 9 8   1009   "T 2 "   5 2 8 9 2 7   4 7 1 6 9 3 0   1009   "T 3 "   5 2 8 9 0 9   4 7 1 7 5 4 0   1027   "T 4 "   5 2 9 6 3 1   4 7 1 7 1 8 8   996   "T 5 "   5 2 9 0 5 1   4 7 1 8 5 6 3   988   "T 6 "   5 2 8 7 0 9   4 7 1 8 8 8 6   998   "T 7 "   5 2 8 9 1 0   4 7 2 0 2 8 3   1084   "T 8 "   5 2 9 1 9 8   4 7 1 9 9 7 2   1052   "T 9 "   5 2 9 5 5 5   4 7 1 9 9 8 6   1081   "T 1 0 "   5 2 9 8 4 3   4 7 2 0 2 1 4   1071       Ko z nica   is   determine d   with   t he   database   E SA   Globco ve r   2009.   Mode li ng   of   the   te rr a in   r oughne ss   was   c onduct ed   by   est imat ing   the   r ough ness   le ng t h   of   the   fiel d   in   acc ord ance   with   the   method ology   of   t he   Evaluation Warning : The document was created with Spire.PDF for Python.
                          IS S N :   2088 - 8 694   In t J   P ow  Ele c  &  D ri   S ys t,   V ol .  12 , N o.   3 ,  Se ptembe r  2021   :    187 2   –   18 79   1874   Euro pean   Atla s   of   the   winds .   By   usi ng   this   da ta base   a nd   t he   software   pac ka ge   WA s P   M a p   E ditor,   the   m ap   of   the   r ough ness   of   te rr ai n   w as   made   t hat   incl ud e d   a   wi der   t arg et   reg i on   co mprisi ng   20 x20   km 2   of   the   te rr it ory   of   the   ta r get   re gion.   Cha nges   in   the   r ough ne ss   of   the   te rr ai n   of   the   ta r get   reg i on   K oz nic a,   wh ic h   was   use d   for   making   the   W AsP   f old e r,   is   sh ow n   in   t he   s at el li te   image   of   the   te r rain   ( Goo gle   Ea rth )   in   the   fig ur e   be low.   In   this   fig ur e ,   the   locat ion   of   W PP   K oz nica   is   ind ic at ed   with   red   c onto ur   li ne .   The   te rr ai n   s how n   in   Fig ure   1   on   wh ic h   the   co nst ru ct io n   of   W PP   K oz nica   is   plan ne d   is   rel at ively   sim ple   in   te rm s   of   r oughne ss   a nd   can   be   descr i bed   with   af forested   valle ys   with   relat ively   hi gh   rou ghne ss,   an d   ba r ed   rid ges   w he r e   the   co ns tr uct ion   of   wind   tu rb i nes   is   plan ne d.   La yout   of   te n   wind   tur bin es   in   Koznica   is   well   s how n   in   F ig ure   2,   w her e   t he   sit ti ng   of   them   is   f oc use d   in   that   wa y   that   te nds   to   s ave   3D   dista nc e .           Figure   1.   The   r oughne ss   ma p   of   the   wide r   te r ra in   at   t he   ta r ge t   reg i on   of   W PP   Ko z nica   (which   is   in dicat ed   in   red   co ntour   li ne )           Figure   2.   Lay out   f or   the   1 0   tu rb i nes   for   the   project   WPP   K oz nica       2.2.    Site   descr iption   and   d at a   for   K itk a   Kitka   wind   farm   sit e   is   in   a   c omple x   mou ntainous   reg i on,   sh ow n   in   F ig ur e   3.   Alth ough   t he   sl op es   of   the   te rr ai n   were   high,   no   cl if f s   we re   ob s er ve d.   Tu rb i nes   a re   plan ne d   on   the   plate au   of   m ountain   rid ge   r unning   north west - s outheast   di recti on.   Sit e   el evati ons   ra ng e   f rom   960   m   to   1090   m   f rom   sea   le ve l.   The   te rr ai n   her e   is   made   up   of   grass   of   ag ricult ur al   la nd   a nd   forest   areas   [2 5 ] ,   [ 26 ].   Since   we   are   deali ng   with   m ounta inous   te rr ai n,   the n   he re   too   the re   are   trees,   but   th ey   are   fa r   f r om   the   place   w he re   the   wi nd   tur bi ne s   are   placed.   Lo w - densi ty   rural   s et tl ements   are   pr ese nt   in   the   vicinit y,   an d   t his   has   bee n   t aken   int o   c ons iderati on   wh ile   wind   tur bin e   micr o   s it ing .     Evaluation Warning : The document was created with Spire.PDF for Python.
In t J  P ow Elec   & Dri S ys t   IS S N: 20 88 - 8 694       Compari son  of  rough ness  i nd ex for  Ki tk a  an d  K oz nic a   wi nd fa rms   ( B uk uri je  H ox ha )   1875       Figure   3.   Vie w   of   K it ka   te r rain   wh e re   t urbin es   are   mou nted   ( photo   ta ke n   be fore   m ounti ng)       Sit e   consi sts   of   7   un it s   of   G E3.6   MW   tu r bi nes   a nd   3   uni ts   of   G E3 .2   MW   tu r bin es ,   as   show n   in   Fig ur e   4 .   Turbine s   a re   locat ed   re ga rd i ng   wind   pote nt ia l,   sit e   acce s sibil it y,   public   la nd   us a ge   an d   pri vate   la nd   us a ge .   Same   as   in   K oz nica   case,   the r e   al so   is   te nde d   to   sa ve   the   di sta nce   of   3D   di sta nce   bet ween   them.   In   t he   c ase   of   Kitka   si nce   we   ha ve   a   c ha ng e   in   the   capaci ty   of   the   t urbines ,   lo ok i ng   at   F ig ur e   4   it   ma y   se em   that   3D   dist anc e   is   not   sa ved   he re.   But   e ve n   her e   t his   dist ance   is   maint ai ned ,   but   sin ce   the   capaci t y   cha nges   the n   their   diamet er   al s o   c hanges   as   is   presented   in   Ta b le   2,   wh e n   we   ha ve   3.6   MW   a nd   3.2 MW.   T he   wind   fa rm   c onsist s   of   7   un it s   of   GE   3.6   MW   t urbines   an d   3   un it s   of   GE   3.2   MW   t urbi nes   wh e re   the   posit ion s   of   them   is   pr ese nted   in   T able   3 .   T he   tu r bin es   a re   locat ed   re ga rd i ng   w ind   po te ntial ,   s it e   acce ssibil ity ,   public   la nd   us a ge   and   pri vate   la nd   us a ge.             Figure   4.   10   wi nd   tu rb i nes   in   Kitka   wind   park       Table   2.   T urbi ne   la yo ut   s ummar y,   us e d   in   Kitka   wind   far m   Turb in e   ty p e   7   x   GE   3 .6 - 137   3   x   GE   3 .2 - 130   Hu b   h eig h t   110   m   Rated   p o wer   3600   kW   &   3200   kW   Nu m b er   of   tu rbin es   10   Ins talled   capacity   3 4 .8   MW     Table   3.   Plac ement   of   wi nd   tur bin es   an d   c oor din at es   for   wind   far m   in   Kitka   Turb in e   No .   X   Y   Level   ab o v e   sea   ( m )   T1   5 4 4 9 1 8   4 7 2 6 4 8 3   9 6 6 .6   T2   5 4 5 2 0 5   4 7 2 5 6 9 5   1 0 0 0 .0   T3   5 4 6 0 3 4   1 7 2 6 5 2 5   1 0 3 9 .0   T4   5 4 6 4 2 3   4 7 2 6 0 9 4   1 0 1 9 .9   T5   5 4 6 7 4 1   4 7 2 5 6 7 1   1 0 9 0 .0   T6   5 4 7 0 7 6   4 7 2 5 9 9 9   1 0 6 0 .0   T7   5 4 7 4 2 7   4 7 2 6 2 2 6   1 0 3 1 .8   T8   5 4 6 5 4 5   4 7 2 4 3 4 1   1 0 7 0 .0   T9   5 4 6 8 7 8   4 7 2 3 9 9 3   1 0 8 0 .0   T10   5 4 7 2 5 8   4 7 2 4 2 3 4   1 0 4 0 .0       Evaluation Warning : The document was created with Spire.PDF for Python.
                          IS S N :   2088 - 8 694   In t J   P ow  Ele c  &  D ri   S ys t,   V ol .  12 , N o.   3 ,  Se ptembe r  2021   :    187 2   –   18 79   1876   2.3.    Basis   f or   comp ariso n   b etw ee n   t he   two   loc ati on s   Fr om   t he   data   pr ese nted   a nd   t ho s e   mea sured   in   t he   fiel d,   s ome   c omparis ons   ca n   be   ma de   f or   the   two   wind   parks,   as :   −   Com par is on   of   the   c hange   in   wind   s pee d   over   the   m on t hs   −   Com par is on   of   al ti tud e   for   ea ch   tu r bin e   in   the   two   wi nd   pa r ks   −   Com par is on   of   the   le vel   of   the   te rr ai n   r ough ness   i nd e x   −   Com par is on   of   horiz on ta l   distance   betwee n   t he   wind   tu r bine s   in   t he   re sp ec ti ve   pa rk s   Durati on   of   mi nimum   wind   s peed   ne ede d   to   sta rt   wi nd   tu rb i ne   a nd   ma xi mu m   wi nd   spe ed   is   al s o   pre sented   for   two   l ocati ons.       3.   RESU LT S   A ND   DI SCUS S ION   The   dia gr am s   in   t he   fo ll owin g   fig ur es   pr ese nt   c omparis on   of   se ver al   im porta nt   par amet ers   betwee n   the   two   l ocati on s .   T he   dia gram   in   F ig ur e   5   pr ese nts   me an   wind   s pee d   f or   t wo   locat i on s   meas ured   in   same   heig ht,   84m.   As   we   ca n   see ,   in   F i gure   5,   as   mean   wind   s pe ed   is   higher   in   Kitka,   al s o   for   diff e re nt   m on t hs   in   Kitka,   wind   spe ed   is   higher .   In   the   sa me   figure   we   pr e se nted   t he   wind   directi on   for   K it ka   an d   Ko z ni ca   f or   one   yea r   meas ur e ment   in   th os e   l ocati on s .   In   t he   oth e r   pa rt,   In   Fig ur e s   6   (a) - ( b )   we   pr ese nted   the   wind   directi on   for   K it ka   an d   K ozn i ca   f or   one   yea r   meas ur e ment   in   th os e   locat ion s ,   w her e   a   is   f or   Kitka   a nd   b   for   Ko z nica .   The   pred om i nan t   dir ect ion   ca n   be   s een   to   be   mai nly   from   t he   s outh - east ,   f or   both   wind   farms.         Figure   5.   Com par is on   of   Kitk a   an d   Ko z nica   moun ta in s   m onthly   wi nd   s pe ed           ( a )   ( b )     Figure   6 .   Com par is on   of   Kitk a   an d   Ko z nica   moun ta in s   wind   directi on ,  ( a )   Kitka   a nd   ( b )   Ko z nica       Win d   di recti on   is   an   el ement   that   mu st   be   ta ken   i nto   c onsiderati on   in   c ompa rison   to   a   la rg e   e xten t   and   e sp eci al ly   for   real   insta ll at ion .   To   ac cur at el y   as ses s   the   directi on   of   t he   wi nd   in   a   place   we   need   measu reme nts   of   at   le ast   one   year.   Ele vatio n   is   al s o   of   high   imp ort ance,   as   can   be   s een   in   F ig ure   6,   al ti tud e   is   higher   in   K ozni ca,   an d   in   tu rbi nes   T8   a nd   T 9.       0 5 10 Kozni c a Ki t ka Evaluation Warning : The document was created with Spire.PDF for Python.
In t J  P ow Elec   & Dri S ys t   IS S N: 20 88 - 8 694       Compari son  of  rough ness  i nd ex for  Ki tk a  an d  K oz nic a   wi nd fa rms   ( B uk uri je  H ox ha )   1877     Figure   7 .   Com par is on   bet wee n   the   al ti tud e   at   wh ic h   the   wi nd   tu rb i nes   a re   instal le d       The   r ugge dnes s   ind e x   (R IX)   is   descr i bed   in   detai l   in   Bowe n   ( 1996) ,   Mo rtense n   ( 1997) ,   and   B ow e n   (2004 ).   The   fo ll owin g   con cl us io ns   re gardin g   R IX   c an   be   ma de:     −   If   the   R IX   is   cl os e   to   ze r o,   th en   the   te r rain   is   ge ner al ly   le s s   ste ep   the n   0.3   an d   the   ai rf l ow   in   the   reg i on   is   li kely   to   be   at ta ched.     −   If   the   RIX   is   gr eat er   tha n   z er o,   the n   pa rts   of   t he   te r rain   are   s te eper   tha n   0.3   an d   flo w   sepa rati on   ma y   occ ur   in   s om e   sect ors   [ 27 ] ,   [ 2 8 ].     dRIX   is   t he   orogra ph ic   perf orma nce   in dicat or.     dRIX   = RIX WTG RIX met,   ma st     Th os e   in dicat or   relat io nships   are   de scri bed   in   F i gure   7   for   Kitka   a nd   K oz nica,   a nd   as   we   s how   in   diag ram.   For   Kitka   as   dRIX   values   bet we en   met   mast   a nd   tur bin e   loc at ion s   a re   in   t he   ra nge   of   2   –   8%,   simi la rity   pri nc iple   can   be   sa id   to   be   m os tl y   achiev ed .   F or   Ko z nica   it   ca n   be   c on cl uded   that   the   predict i on   of   pro du ct io n   f or   wind   t urbine s   1 -   8   is   gen e rall y   a ccepta ble,   wh il e   f or   the   t urbine   9   an d   10   t he   unce rtai nt y   in   t he   est imat ion   of   pro du ct io n   is   s ign ific a ntly   hig he r   beca us e   dR IX   for   tu r bine   9   is   8   %,   a nd   for   tu rb i ne   10   it   is     11   %.   In   a dd it i on,   the   tu rb i ne s   8,   9   a nd   10   a re   locat e d   at   a bout   4   km   of   t he   meas ur in g   m ast ,   so   the   e sti mati on   of   pote ntial   in   t hese   l ocati ons   is   with   si gn i ficant   unce rtai nty.   Fr om   wh at   we   can   see   f rom   t he   in sta ll at ion   of   wind   t urbin es   f or   both   pa r ks ,   refe r red   to   as   Kitka   an d   Ko z nica,   it   fo l lows   t hat   the   tur bin es   T1   a nd   T2   have   the   la rg e r   distanc e   com pa red   with   oth e r   t urbines   in   Kitka   a nd   sam e   tur bin e s   T7   and   in   K oz nica,   an d   w he n   we   co mp a re   e ne rgy   pro du ct i on   those   distance s   ar e   very   i nterested   in   wind   tu r bine s   interact io n   a nd   total   en er gy   pro duct ion.         Figure   8 .   Re la ti on s hip   bet wee n   RI X   a nd   dRIX,   for   K ozn ic a   an d   Kitka   wind   parks       4.   CONCL US I O NS     The   pa rt   that   is   cu rr e ntly   ope rati ng   as   a   wind   park,   Kitka   is   locat ed   on   the   east er n   si de   of   K oso vo   and   al s o   the   sit e   wh e re   meas ureme nts   were   made   in   t hat   pa rt,   na mely   K oz nica.   T he   anal ys is   sho ws   that   Kitka   has   a   dRIX   big ge r   tha n   K oz nica,   but   e ve n   this   ha rs hn es s   of   te rr ai n   has   not   aff e ct ed   t he   ov e rall   pote ntial   -2 0 2 4 6 8 10 12 0 2 4 6 8 10 12 d R IX Turbi n e   No . Koz nica Dri x Kitk a Drix Evaluation Warning : The document was created with Spire.PDF for Python.
                          IS S N :   2088 - 8 694   In t J   P ow  Ele c  &  D ri   S ys t,   V ol .  12 , N o.   3 ,  Se ptembe r  2021   :    187 2   –   18 79   1878   energ y   pro du ct ion   as   m uch   as   the   wi nd   s pee d,   due   to   the   s hap e   of   the   te r rain   that   e na bles   it.   M a ny   ti mes,   in   the   case   of   pr a ct ic al   reali zat i on   wh e n   we   a r e   de al ing   with   the   sa me   te rr ai ns ,   as   in   this   moun ta in ous   c ase   a nd   wh e n   a pproxi mate ly   the   wi nd   blows   in   one   directi on,   RIX   are   ta ken   the   same.   F rom   this   analy sis   we   can   con cl ud e   t hat   this   a ppro ac h   sh oul d   not   be   su c h.   Re ga rd i ng   t he   e ff ic ie nc y   of   t he   t urbin es   us ed ,   it   de pe nds   la rg el y   on   the   wind   spe ed ,   but   the   hei ght   of   the   tu rb i nes   is   an   im portant   factor   as   well ,   due   to   the   ve locit y   change   with   he igh t.   Ca lc ulati on s   s how   that   tur bin es   hav e   t he   highest   ef fici en cy,   as   e xp e ct ed,   at   Kitka ,   due   to   the   hi gh e r   wi nd   s peed s .   On   t he   ot her   ha nd,   as   mentio ne d   above,   t her e   w ere   two   di ff e re nt   type s   of   ca pa ci ty   tur bin es,   3.2   MW   a nd   3.6   MW.   An   el e ment   that   has   an   im pact   on   the   ove rall   powe r   ge ne rati on   is   t he   di sta nce   betwee n   the   tu rb i nes.   For   sta ble   ope rati ng   c onditi ons,   it   is   necessa ry   f or   them   to   sta y   in   3ꞏD   distances .   If   we   consi der   that   the   t urbines   will   be   in   operati on   for   5000   ho ur s   durin g   t he   year,   t hen   this   will   res ult   in   a nnual   pro du ct io n   of   a bout:   5582 9.4   MWh   at   K oz nica ,   an d   5501 9.873   M W h   at   K it ka   wind   pa rk ,   and   total ly   110.84 9   GWh.   T he   dif f eren ce   of   ene r gy   producti on   from   th os e   t w o   wind   farms   is   80 9.527   MW h.   Acc ordin g   to   data   from   the   Ene rgy   Re gu la to r y   Office   of   K oso vo,   it   fo ll ows   t hat   the   an nual   aver a ge   of   e ne rgy   us e d   in   Kosovo   is   583500 0   G Wh/ year ,   so   by   usi ng   th os e   wind   fa rms,   we   will   ha ve   0.0 018%   of   el ect rical   ene rgy   ge ne ra te d   by   tho se   two   wind   farms.       REFERE NCE S     [1]   D.   Lom b ard i ,   “ Dyna mics   of   off shore   wind   tu rbi nes , ”   MSc   the sis ,   Univer si ty   of   B ristol :   Br istol ,   U K,   2010.   [2]   A.   H.   Almukh ta r ,   “ Eff e ct   of   dra g   on   the   per for mance   for   an   eff i cient   wind   turbi n e   bla de   design ,”   Ene rgy   Proce di a ,   vol.   18 ,   pp .   404 - 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