Effect Ove Ditibution Feede of High Penetation Level of WECS Baed on Induction Geneato F. Gonzalez-Longatt, Membe, IEEE, E. Gavoki, M. Boliva Abtact In i pape, imulation on teady tate ove a typical adial ditibution feede wi eveal penetation and dipeion level of ditibuted geneation uing wind tubine baed on induction geneato i developed. A MATLAB powe flow pogam wi a deailed model of ingle quiel cage induction machine i ued to quantitatively demontate inheent typical weak chaacteitic of e ditibution ytem at make undeiable e ue of lage wind tubine baed on induction geneato. Reult of ee tudie ae hown hee. Index Tem Ditibution feede, eactive powe flow, eactive powe uppot, and wind enegy conveion ytem baed on induction geneato I. INTRODUCTION S eult of inceaing envionmental concen, e A impact of conventional electicity geneation on e envionment i being minimized and effot ae made to geneate electicity fom enewable ouce []. The main advantage of electicity geneation fom enewable ouce ae e abence of hamful emiion and e infinite availability of e pime move at i conveted into electicity [], []. One way of geneating electicity fom enewable ouce i to ue wind tubine at convet e enegy contained in flowing ai into electicity [3]. In ecent yea wind enegy ha become an impotant pat of electical geneation in many countie and it impotance i continuing to inceae [4], [5]. Up to i moment, e amount of wind powe integated into lage-cale electic powe ytem only cove a mall pat of e total powe ytem load [6]. The et of e powe ytem load i fo e laget pat coveed by conventional emal, nuclea, and hydopowe plant. But tendency to inceae e amount of electicity geneated fom wind can be obeved. Theefoe, e penetation of wind tubine in electical powe ytem will inceae and ey may begin to influence oveall powe ytem behavio. In paticula, e new paadigm of ditibuted geneation i F. González-Longatt, E. Gavoki and M. Boliva ae wi Depatment of Electical Engineeing, Univeidad Nacional Expeimental Politécnica de la Fueza Amada, Maacay, Aagua, Venezuela (e-mail: fglongatt@ieee.og, juane586@yahoo.com avillaana@yahoo.com cpeazam@cantv.net. F. Gonzalez-Longatt i PhD tudent, Univeidad Cental de Venezuela, Caaca, Venezuela (e-mail: flongatt@elecic.ing.ucv.ve. giving ie to inteconnection of mall poduction unit wi e public utility MV o LV netwok [5]. Due to economical and ome technical eaon quiel cage induction machine eult attactive to be ued i wind tubine cheme. It conit of a conventional, diectly gid coupled quiel cage induction geneato. The lip, and hence e oto peed of a quiel cage induction geneato vaie wi e amount of powe geneated. Thee oto peed vaiation ae, howeve, vey mall, appoximately to pe cent. Theefoe, i wind tubine type i nomally efeed to a a contant peed o fixed peed tubine [7]. The wind tubine ytem uing taditional quiel cage induction machine i attactive to be connected on ditibution ytem, but a geat numbe of geneation unit peent ome technical challenge to utilitie. In i pape e teady tate effect of high penetation level of wind tubine uing quiel ingle cae induction geneato. II. MODELING It i well known at ditibution netwok ae typically adial and paive, wee deigned fo one diection powe flow. The inteconnection of wind tubine geneato inject powe in diffeent point of e netwok, whee only conumption have been peviouly planned. Theefoe e peence of i geneation unit in MV ditibution netwok can caue eveal poblem, namely: Voltage egulation difficultie at e HV/MV ubtation. Shot-cicuit level inceae; The need fo potective device coodination; Tanient voltage dip eulting fom induction geneato inteconnection. Thee fact ae peenting technical challenge to e utilitie. In ode to evaluate e impact of wind tubine on ditibution netwok, imulation mut be developed to ovecome e technical opeation poblem and enue a afe and eliable opeation. Thi pape i focalized on detemine e effect of high penetation level of wind tubine wi induction geneato on voltage egulation and powe loe; in ode to evaluate e impact on ee vaiable teady tate imulation mut be doing; load flow analyi. When a wind tubine o wind fam wi ingle cage induction machine geneation i to be include in a load flow
analyi e PQ, R and P bue ae e mot commonly ued. A. Single Squiel Cage Induction Geneato-Wind Tubine A way to imulate a wind tubine i to aume a geneated active powe and a given powe facto, wi witch e conumed eactive powe i calculated. Some impovement can be achieved if e teady tate model of e induction machine i take in account (Steinmetz model, Fig. [5], [8]. + U R I j j m j I R Fig.. Steady tate equivalent cicuit of induction machine. Poitive phae equence of balanced opeation. R : tato eitance, : Stato eactance, m : Magnetizing eactance, R : Roto eitance (efeed to tato, : Roto eactance (efeed to tato, : lip (negative fo geneato opeation, U: Voltage applied, I : Stato cuent, I : oto cuent. The active powe i calculated fom e wind peed fo i fit iteation of e powe flow analyi, and fom en it value i emain a a contant. The eactive powe depend on e active powe and e bu voltage. In i cae, we ae decided calculating e eactive powe a a function of e voltage. ( U + R + R Q + + T = ( ( ( R + R + + m R + whee R and, ae Thevenin eitance and eactance epectively, bo view fom magnetizing eactance. The value of eactive powe pecified i updated each iteation; and i value i etimated fom e teady-tate equivalent cicuit of e induction machine. A econd ode polynomial, calculate lip fom mechanical powe and, conideing teminal voltage eactive powe i update. α + α + α = ( whee: α = P h R α = R P α = R R P h + P h h ( + R V + R V The wind peed (v w i datum and active powe can be obtained a a function of it. Thi i done by mean of e powe cuve fo e tubine and next equation [9]: 3 Ph = ρac pv (3 w whee A i e oto aea, ρ i e denity of ai and C p i e powe coefficient of wind tubine. The powe coefficient i obtainable a a function of e tip peed atio, λ = (ωr/v w, whee ω i e oto peed and R i it adiu. III. SIMULATIONS The elevant eult of e teady tate imulation of 6.6 kv Kumamoto ditibution feede (Figue including wind tubine baed on induction geneato ae peented in i ection. The teady tate behavio of e tet ytem wa imulated by a pogam on MATLAB developed by e auo. Thi pogam eolve e load flow poblem, wi a Newton-Raphon iteative meod, and fully configuable to develop load flow tudie. The load node ae modeled a PQ node. Thee ae modeled a contant powe load at i independent of voltage level. A. Tet Feede To exanimate e effect of penetation level of wind tubine baed on induction geneato on a typical adial netwok. A modified veion of e ditibution feede in e Kumamoto aea of Japan [] i ued in e tudie. The netwok paamete can be found in Appendix A, whee e bae powe i MVA and e bae line voltage i 6.6 kv. The load ae conideed a contant powe and e total load in i ditibution ytem i P load = 8.9 MW, Q load =.3 MVAR. Fig. how e tet ytem ued oughout e imulation, and location of load, ae alo hown. 3 4 5 6 5 4 3 9 8 7 Fig.. Kumamoto 5-bu ditibution ytem online diagam [] B. Wind Tubine Fo imulation pupoe, tall egulated wind tubine wi induction geneato i conideed. The aea wept by e blade of e wind tubine i 86 m, e hub height i 3m, and e ated powe i 335 kva. TABLE I WIND TURBINE INDUCTION GENERATOR PARAMETER Paamete Value Nominal Voltage 66 V Nominal Powe 335 kva Roto eactance.639 p.u Stato eactance.878 p.u Roto eitance.6 p.u Stato eitance.57 p.u Magnetizing eactance.78 p.u Inetia contant 3.5 Table I how e paamete of e induction geneato and Figue 3, how e output powe and powe coefficient of e
3 wind tubine. Evey wind tubine i connected to ditibution feede ough tep-up tanfome. Output Powe [kw] 5 4 3 Powe Coefficient Output Powe 5 5 5 Wind Speed (m/ Fig. 3. Output powe and powe coefficient of wind tubine conideed C. Simulation Sceneie To define and chaacteize e effect of wind tubine wi induction geneato main imulation cenaio would be defined. Some quantitative indicato would be defining e value and abdication of geneato to be integated on ditibution feede: Penetation level, Dipeion level. Penetation Level (%Penetation i faction of total load (P load eved by ditibuted geneation (P DG : PDG % Penetatio n = % (4 P load The key cenaio of penetation level ae (Table II: Low Penetation Level: conide a penetation level below 3%. Semi-ideal Penetation Level: Capacity of geneation intalled in i cenaio i e half of all load intalled. Ideal Penetation Level: We conide geneation intalled wi a capacity equal to all load intalled. Utopic Penetation Level: In i cenaio geneation capacity i moe an all load intalled, poibility of enegy expotation to powe utility i poible. TABLE II MAIN CHARACTERISTIC OF PENETRATION LEVELS SCENARIOS Cae Numbe Penetation Level P GD [MW] Cae Identification Name VI 5.% 8.3545 Utopic V.% 8.93 Ideal IV 5.% 9.455 Semi-Ideal III 3.% 5.679 III II.% 3.786 II I.%.893 I Dipeion Level (%Dipeion, i atio between numbe of node wi geneation (#GDBu to numbe of node wi load (#LoadBu. # DGBu % DipDG = % # LoadBu (5 The main cenaio wi penetation level ae following (Table III: Low Dipeion Level: % and 8% level i conideed. Semi-ideal Level: Geneation ae intalled in half of all node. Ideal Level: In i cae total dipeion i conideed, geneation i intalled in each bu.,6,5,4,3,, Powe Coefficient (- TABLE II MAIN CHARACTERISTIC OF DISPERSION LEVELS SCENARIOS Dipeion Level Numbe of Bue wi GD Cae Identification Name.% 4 Ideal 9.857% 3 85.74% 78.57% 7.49% 64.86% 9 57.43% 8 5.% 7 Semi-Ideal 4.857% 6 35.74% 5 8.57% 4 Low.49% 3 Low 4.86% Low 7.43% Vey Low IV. RESULTS The teady tate behavio of e tet ytem wa imulated by a pogam on MATLAB developed by e auo. Thi pogam eolve e load flow poblem, wi a Newton- Raphon iteative meod, and include wind tubine wi induction geneato by PQ bu model. A maximum powe eo of -3 p.u wa conideed. Peliminay imulation only wi powe utility geneato, eveal an acceptable voltage pofile (between.95 and.5 p.u. (Figue 4. 99.78% % 99.745% 99.764% 99.3989% 99.3599% 99.3393% 3 4 5 6 5 4 3 99.447% 99.59% 99.453% 99.43% 98.553% 99.5348% 98.7589% 99.79% 9 8 7 Fig. 4. Kumamoto 5-bu ditibution ytem load flow eult Active powe loe ae nea of.6 p.u, but when e penetation level of wind tubine become high active loe come high, at geneation about % of total load active powe loe ae.7 p.u, at low level of dipeion. Figue 5 how behavio of active powe loe fo all penetation and dipeion level. High loe of active powe wee found on high penetation level and lowet dipeion level. At contant penetation level, low active powe loe wa found wi high penetation level.
4..98 Pédida Activa [p.u] -. -. -.3 -.4 -.5 Voltaje [p.u].96.94.9.9 -.6 -.7.4..8 Nivel de Penetación [%].6.4. 3 4 5 6 7 8 Nivel de Dipeión [%] Fig. 5. Active powe loe veu penetation and dipeion level Potencia Impotada [p.u].7.6.5.4.3.. -. 5 Nivel de Penetación [%] 5 9 8 7 6 5 Nivel de Dipeión [%] Fig. 6. Active powe flow fom utility. Minu ign mean powe flow to utility ytem Penetation level bigge an % in i adial feede caue a change on active powe flow diection. Bellow % penetation level active powe flow come fom utility ytem, but ove % geneato connecte on ditibution feede geneate moe powe an all load connected, en active powe i expoted fom ditibuted geneato (ee Fig. 6. Induction Reactive powe flow wi induction geneation wind tubine gow wi mechanical powe inceae, en when moe favoable wind peed ae available moe high penetation level would be each, but conumption of eactive powe i expected in all cae. To impove e powe facto it i common to fit local powe facto coection capacito on e teminal of e geneato. In i cae, high penetation level implie a conideable numbe of mall geneato connected to e ditibution feede, wi low hot cicuit level, including e effect of geneato tanfome, en additional eactive powe i dawn fom e utility. The voltage egulation in ditibution feede wind tubine wi induction geneato became a eiou poblem. In Figue 7, voltage pofile i hown fo eveal penetation level at maximum dipeion level. A lage numbe of node ae below acceptable voltage level (.95 p.u at all penetation level. Voltage egulation difficultie ae peent wi high penetation and high dipeion level; mainly due e eactive conumption of induction geneato, low hot cicuit level of e feede. 4 3 9.88 9 3 4 5 Nivel de Penetación [%] 3 4 5 6 7 8 9 3 4 5 Fig. 7. Voltage pofile fo eveal penetation level conideing a % dipeion level V. CONCLUSIONS The integation of wind tubine uing induction geneation i invetigated in i pape. A typical ditibution feede wa imulated in teady tate a powe flow pogam including taimetz induction machine model in PQ bue. Seveal penetation and dipeion level wee imulated. Simulation demontated e inheent typical weak chaacteitic of e ditibution ytem at make undeiable e ue of lage wind tubine baed on induction geneato, becaue e high eactive conumption of eactive powe. Finally conideation of eactive uppot and compenation level wa demontated due a poo voltage pofile at high penetation and dipeion level. VI. APPENDI TABLE A. LINE AND LOAD DATA OF KUMAMOTO DISTRIBUTION SYSTEM [] Sending Ending Pload Qload R (p.u (p.u B (p.u Node Node (p.u (p.u.35.757..8. 3.33.849.5.495.5 3 4.667.388.355.958.98 4 5.579.4949.5.44.45 5 6.44.36547..3. 4 7.8.3696.3.638.66 7 8.9.4575..33.33 8 9.7.3346.5.3. 9.367.694.35.8.9.9.4575..7. 3.75.743..3.4 3.35.845..9.3 3 4.3965.984..6.6 4 5.6.453..39.4 Bu voltage = 6.6kV, Bae MVA = MVA VII. REFERENCES [] F. Gonzalez-Longatt and C. Fotoul. Review of Ditibuted Geneation Concept: Attempt of Unification. Poceeding of Intenational Confeence on Renewable Enegie and Powe Quaility (ICREPQ 5, Epaña, 5. [] C. Peaza, F. González-Longatt and C. Villanueva. Dynamic Pefomance Implication of e Powe Conditione Gid-Connected fo Photovoltaic Souce. in Poc. ICREPQ 5, Zaagoza, Spain, 994, pp. 7. [3] J. G. Slootweg, S. W. H. de Haan, H. Polinde,, and W. L. Kling, Geneal Model fo Repeenting Vaiable Speed Wind Tubine in Powe Sytem Dynamic Simulation. IEEE Tanaction On Powe Sytem, Vol. 8, No., pp. 44-5. Febuay 3 Baa
5 [4] J. A. Peça, F. P. Maciel, and J. Cidá, Simulation of MV ditibution netwok wi Aynchonou local Geneation Souce, in Poceeding of IEEE Melecom 9, June 99 [5] A. Feijóo and J. Cidá, Modeling of Wind Fam in e Load Flow Analyi, IEEE Tanaction on Powe Sytem by Vol. 5, No., pp. -5, Febuay. [6] González Longatt, F (5. Dynamic Model of vaiable Speed WECS: Attend of Simplification. In poceeding of Fif Intenational Wokhop on Lage-Scale of Integation of Wind Powe and Tanmiion Netwok fo Offhoe Wind Fam. 7-8 Apil, 5, Glagow, Scotland, 5. [7] J. G. Slootweg. Wind Powe. Modeling and Impact on Powe Sytem Dynamic. PhD Thei. Univeity of Delft. Decembe, 3 [8] P. Kundu, Powe Sytem Stability and Contol. Mc Gaw hill, 994. [9] L. L. Fei, Wind Enegy Conveion Sytem: Pentice-Hall, 97. [] S. Li, Tomovic, and T. Hiyama, Load Following function uing ditibuted enegy eouce, Poceeding of e IEEE PES Summe Meeting, Seattle. July. VIII. BIOGRAPHIES Fancico M. González-Longatt (S 998, M 5. He eceived e electical enginee degee fom Intituto Univeitaio Politécnico de la Fueza Amada Nacionale, Venezuela, in 994, and Mate of Buine Adminitation fom Univeidad Bicentenaia de Aagua, Venezuela, in 998. He i cuently woking fo PhD degee of Univeidad Cental de Venezuela, eeaching on e impact of e ditibuted geneation on dynamic tability of electical powe ytem. He i aitant Pofeo of Univeidad Nacional Politécnica de la Fueza Amada (UNEFA, Venezuela ince 994. He i membe of IEEE Powe Engineeing, Induty Application and Powe Electonic ocietie. He wa diecto of e UNEFA Electical Engineeing Depatment and founde of e powe ytem eeach cente on UNEFA. He ha witten book on tanient tability of powe ytem, and ha been lectue on egional and intenational meeting. Hi main aea of inteet i e dynamic behavio of ditibuted enegy eouce and e impact on e powe ytem tability. He ha auoed moe an 3 technical pape and epot in i aea. Enique Gavoki Souto i gaduated of Univeidad Expeimental Politécnica de la Fueza Amada Nacional, Venezuela (6, and hi main eeach inteet ae on enewable enegy and wind powe integation. Manuel Boliva Olate i gaduated of Univeidad Expeimental Politécnica de la Fueza Amada Nacional, Venezuela (6, Hi main inteet i ditibuted geneation and enewable eouce.