Intenational Jounal of Recent Technology and Engineeing (IJRTE) ISSN: 2277-3878, Volume-2, Iue-2, May 2013 Impovement Fault-ide Though of DFIG Baed Wind Tubine by Uing a Seie Compenation Technology with Emphai Put on the Mitigation of Voltage Dip Mutafa Jawad Kadhim, D.S.Chavan Abtact Low Voltage Ride Though i an impotant featue fo wind tubine ytem to fulfill gid code equiement. In cae of wind tubine technologie uing doubly fed induction geneato the eaction to gid voltage ditubance i enible. Hadwae o oftwae potection mut be implemented to potect the convete fom tipping duing evee gid voltage fault. In thi pape the Dynamic Voltage Retoe (DVR) olution fo LVRT of DFIG wind tubine i invetigated by imulation eult uing a detailed convete model conideing the witching and appopiate 2 MW wind tubine ytem paamete. To how the effectivene of the popoed method the eult ae compaed to a conventional fault ide though of the DFIG uing a cowba cicuit. Meauement eult on a 22 kw laboatoy DFIG tet bench how the effectivene of the popoed contol technique. Theefoe the time taken fo the cowba cuent to each zeo i cucial a it detemine when the RSC can egain powe contol and how oon the AC voltage can ecove. It i een that the cowba cuent can take a long time to deceae to zeo and that thi ha a ignificant impact on the voltage ecovey afte fault. The lage the cowba eito and the futhe the geneato i fom ynchonou peed, the hote the cowba cuent tanient i. Powe and enegy diipation though the cowba eito ae alo conideed, and it i obeved that the powe vaie in accodance with the maximum powe tanfe theoem. It i een that eactive powe contol duing fault cleaance can ait AC voltage ecovey. Thi i not acceptable when Index Tem Doubly fed induction geneato (DFIG), dynamic voltage etoe (DVR), fault ide-though and wind enegy. I. INTRODUCTION Due to high depletion of conventional enegy ouce and inceaing envionmental concen, moe effot ae put in electicity geneation fom enewable enegy ouce. Among vaiou enewable enegy ouce, wind powe i the mot apidly gowing one ince the 20th centuy due to it epoducible, eouceful and pollution-fee chaacteitic. Among the wind tubine concept, tubine uing the doubly fed induction geneato (DFIG) ae dominant due to it vaiable-peed opeation, it epaately contollable active and eactive powe, and it patially ated powe convete. But the eaction of DFIG to gid voltage ditubance i enitive, fo ymmetical and unymmetical voltage dip, and equie additional potection fo the oto ide powe electonic convete [1].Conventionally a eitive netwok called cowba i connected, a decibed in [2],[3],[4] and [5]. once the cowba i applied it cannot be emoved until it cuent eache zeo. Duing the peiod the cowba i applied, the machine behave a a conventional FSIG, loing contol of the active and eactive powe. Fig 1: Schematic diagam of DFIG wind tubine ytem conideing gid code equiement [6]? Thu othe potection method have to be invetigated to ide though gid fault afely and fulfill the gid code. If an extenal powe electonic device i ued to compenate the faulty gid voltage, any potection method in the DFIG ytem can be left out. Such a ytem i intoduced in [7] and i called a dynamic voltage etoe (DVR).The dynamic voltage etoe i a eie connected device, which by voltage injection can contol the load voltage. In the cae of a voltage dip the DVR inject the miing voltage and it avoid any tipping the load. Fig. 2 illutate the opeation pinciple of a DVR. Manucipt eceived on May, 2013. Mutafa Jawadkadhim Al-Tameemi,wa bon in Baghdad, Iaq on Jan 16,1986.He eceived B.Sc Degee in depatment of electical engineeing at Univeity of Technology,Baghdad,Iaq Pof. D.S. Chavan:Ph D (Regiteed), ME (Electical), BE (Electical), DEE Aociate Pofeo, Co-odinato (R&D cell),co-odinato (PH.D.Pogamme management) Bhaati Vidyapeeth Deemed Univeity College Of Engineeing Pune 411043 Fig. 2: opeation pinciple of a DVR. 212
Impovement Fault-ide Though of DFIG Baed Wind Tubine by Uing a Seie Compenation Technology with Emphai Put on the Mitigation of Voltage Dip The application of a dynamic voltage etoe (DVR)connected to a wind-tubine-diven doubly fed induction geneato(dfig) i invetigated and compaed to aconventional fault ide though of the DFIG uing a cowba cicuit. The pape i tuctued a follow. In ection 2 the DFIG wind tubine ytem and it contol tuctue ae decibed. The DVR contol anddeign decibed in ection 3. Simulation eult fo a 2 MW wind tubine in ection 4 in ection 5 how the effectivene of the popoed techniquein compaion to the low voltage ide though of the DFIG uing a cowba. A concluion cloe thepape. II. DFIG Fo vaiable-peed ytem with limited vaiable-peed ange, e.g. 30% of ynchonoupeed, the DFIG can be an inteeting olution [8]. A mentioned ealie the eaon fothi i that powe electonic convete only ha to handle a faction (20 30%) of the totalpowe [9, 10]. Thi mean that the loe in the powe electonic convete can be educedcompaed to a ytem whee the convete ha to handle the total powe. d V RI L j...(1) d V R I L j lip...(2) L I L I...(3) L I h L h I...(4) Whee ψ, U and I epeent the flux, voltage and cuent vecto epectively. Subcipt and denotethe tato and oto quantitie epectively. L = L σ +L h and L = L σ +L h epeent the tatoand oto inductance, L h i the mutual inductance, R and R ae the tato and oto eitance andw lip i the lip angula fequency w lip = w w mech.the oto cuent ae contolled by the oto ide voltage ouce convete. Subtituting I =ψ /L (L h /L )I fom (3) in (2) and auming the tato flux to be contant (d ψ /d t = 0) yielhe oto voltage equation: V R I di L j lip...(5) that i ued to deign the inne cuent loop contolle, whee jw lip ψ i ued a decoupling tem.the tato active and eactive powe can be contolled independently by the oute contol loop.the line ide convete contol the voltage V and povide eactive powe uppot. The linecuent I l can be contolled by adjuting the voltage dop aco the line inductance L l giving thefollowing dynamic: V di1 R1L 1 L1...(6) Fig 3: Schematic diagam of DFIG wind tubine contol tuctue. In addition, the cotof the convete become lowe. The tato cicuit of the DFIG i connected to the gid whilethe oto cicuit i connected to a convete via lip ing, ee Fig. 1. Amoe detailed pictue of the InvetigatedDFIG ytem with a back-to-back convete can be een in Fig. 1. The back-to-back convete conit of two convete, i.e., machine-ide convete and gid-ide convete that ae connected back-to-back. Between the two convete a dclink capacito i placed, aenegy toage, in ode to keep the voltage vaiation (o ipple) in the dc-link voltage mall. With the machine-ide convete it i poible to contol the toque o the peed of the DFIG and alo the powe facto at the tato teminal, while the main objective fo the gid-ide convete i to keep the dc-link voltage contant. The peed toque chaacteitic of the DFIG ytem. The DFIG can opeate both in moto and geneato opeation with a oto-peed ange of ±Δωmax aound the ynchonou peed, ω1. The oveall contol tuctue i hown in Fig.3 The mathematical model of the DFIG will only biefly be dicued hee. Fom the pe-phae equivalent cicuit of the DFIG in an abitay efeence fame otating at ynchonou angula peed w the following tato and oto voltage and flux equation can be deived. ued to deign the cuent contolle, while the voltage dynamic can be expeed by: C dv I I...(7) load ued to deign the oute voltage contol loop, whee C i the capacitance and I and I load ae the cuent on LSC and RSC ide, epectively. III. DFIG PROTECTION 3.1 Cowba: To potect the oto ide convete fomtipping due to ovecuent in the oto cicuit o ovevoltage in the link duing gid voltage dip a cowba i intalled in conventional DFIG wind tubine, which i a eitive netwok that i connected to the oto winding of the DFIG. The cowba limit the voltage and povide a afe oute fo the cuent by bypaing the oto by a et of eito. When the cowba i activated the oto ide convete pule ae diabled and the machine behave like a quiel cage induction machine diectly coupled to the gid. The magnetization of the machine that wa povided by the RSC in nominal condition i lot and the machine abob a lage amount of eactive powe fom the tato and thu fom the netwok [6], which can futhe educe the voltage level and i not allowed in actual gid code. Tiggeing of the cowba cicuit alo mean high te to the mechanical component of the ytem a the haft and the gea. Detailed 213
analye on the DFIG behavio duing voltage dip and cowba potection can be found in [2] and [6]. Thu, fom netwok and fom machine mechanical point of view a cowba tiggeing hould be avoided. Anyway, to compae the peented technique hee with a conventional DFIG wind tubine ytem potected by a cowba cicuit, imulation eult including cowba potection ae examined. Theefoe the cowba eitance i deigned. The value of the cowba eitance hould be choen caefully.thee ae two equiement that give an uppe and a lowe limit to the cowba eitance. Ithould be high enough to limit the hot cicuit oto cuent and it hould be low enough to avoid toohigh voltage in the oto cicuit. If the voltage aco the cowba teminal ie above the -linkvoltage of the RSC high cuent will flow though the antipaallel diode of the convete. Appopiate Cowba eitance ae deigned in [6] and [5]. A cowba eitance of Rcow= 150R iued in the imulation. Thee ae appoache limiting the opeation time of the cowba to etunto nomal DFIG opeation with active and eactive powe contol a oon a poible. A hyteei Contol tiggeed by the oto cuent i peented in [4] and alo applied hee.when the abolute value of the oto cuent eache a maximum thehold value the cowba i fied and the RSC i blocked. When the oto tanient have died out and the abolute value of the oto cuent i below a minimal thehold value the cowba i witched off and the RSC contol i etated. A eet of the integal value of the RSC cuent and powe contol befoe etat i neceay to avoid ovecuent. 3.2 DVR Potection: The DVR i a poweful contolle that i commonly ued fovoltage ag mitigation at the point of connection. Fig. 4 how the baic configuation ofdvr. Intenational Jounal of Recent Technology and Engineeing (IJRTE) ISSN: 2277-3878, Volume-2, Iue-2, May 2013 the DVR compenate a voltage ag, the active powe of the DFIG i patly fed into the gid and the DVR ytem that i dependent of the emaining gid voltage. The active powe flowing into the DVR chage it dc link. The exce enegy mut eithe be deliveed to an enegy toage ytem o tanfomed into heat by a dc choppe. Note that fo full compenation of a full voltage dip, the DVR mut be ated fo the powe of the wind tubine, making the olution in economical. Thu, the olution will pobably be implemented to fully compenate the line voltage duing patial voltage dip o well and to ait duing full voltage dip. The injection tanfome have a geat impact on the DVR deign. To adapt the DVR dc voltage to the compenating voltage, an adequate tanfome atio mut be choen. The deign of the injection tanfome diffe fom nomally ued hunt tanfome. They mut be highe ated to avoid poible atuation effect and lowe the ik of high inuh cuent that mut be handled by the convete. Rating and deign iue fo the injection tanfome ae given in [13]. In pactical application, eveal ecuity iue mut be conideed. Since the DVR i connected in eie to the load, bypa witche aco the tanfome mut be included to diconnect the DVR fom the load, to potect the convete fom damage in oveload ituation. Fig 5: Matlab/Simulink fo the popoed model Fig 4: Baic configuation of DVR. The VSC geneate a thee-phae ac output voltage which icontollable in phae and magnitude. Thee voltage aeinjected into the ac ditibution ytem in ode to maintain theload voltage at the deied voltage efeence. in [11]. The ating of the DVR ytem depend mainly on thedepth of the voltage fault that hould be compenated. Fo voltageag o well with zeo-phae angle jump, the equiementof active powe of the DVR i imply given by: P V V 1 2 DVR P load V1...(8) whee V1 i the nominal and V2 the faulty line voltage. Note thatpecial focu mut be taken on voltage fault with phae angle jump that can lead to a highe powe ating [12].When III. SIMULATION RESULTS To how the effectivene of the popoed technique, imulation have been pefomed uing MATLAB/Simulink and PLECS fo a 2 -MW DFIG wind tubine ytem and a DVR, a hown in Fig. 1. The contol tuctue, a hown in Fig. 3, i implemented in Matlab/Simulink a how in fig 5, while all powe electonic component ae modeled in PLECS. The ytem pefomance of the DFIG i hown in Fig. 6, potected by the conventional paive cowba, and in Fig. 7, potected by the DVR duing a two-phae 37 % voltage dip of 100 m duation [ee Fig. 6(a) and 7 (a)]. The DFIG eact with high tato cuent I, and thu, high oto cuent ae induced in the oto cicuit. When the oto cuent exceed the maximum level, the cowba i tiggeed to potect the RSC fom ovecuent IRSC [ee Fig. 6(e) and (f)]. When the voltage level ha been eetablihed and tanient have decayed, the cowba can be deactivated, which i not hown hee. When the RSC i in opeation, the machine magnetization i povided by the oto, but when the cowba i tiggeed, the RSC i diabled and the machine excitation i hifted to the tato. Thu, eactive powe contol cannotbe povided duing the voltage dip [ee Fig. 6(h)], which i not acceptable when conideing the gid code. The machine cannot geneate enough toque o that the oto acceleate, which can lead to diconnection of the 214
Impovement Fault-ide Though of DFIG Baed Wind Tubine by Uing a Seie Compenation Technology with Emphai Put on the Mitigation of Voltage Dip tubine due to ovepeed. The DVR i not activated in the imulation, a hown in Fig. 6. When the wind tubine ytem i potected by the DVR, a hown in Fig. 7, the voltage dip can almot be compenated [ee Fig. 7(c)]. The DFIG epone i much le citical, which mean that lowe tato ovecuent and oto ovecuent ae poduced o that the cowba doe not have to be tiggeed [ee Fig. 7(d) (f)]. Note that although the tato voltage dip i faily well-compenated, a light ditotion in the tato cuent (dc component), and thu, ditubed oto cuent can be obeved. Anyway, the RSC emain in opeation and can contol tato active and eactive powe independently. Thu, the peed i kept contant and a eactive powe poduction (Q = 0.5Mva) duing gid fault a demanded in gid code i pefomed. Note that a communication between DVR and DFIG i neceay. In Fig. 7(i), the DVR powe to compenate the voltage dip i hown. It become clea that the active and eactive powe that cannot be fed into the faulty gid duing gid fault mut be conumed by the DVR. (h) (i) Fig 6: Simulation of DFIG pefomance with cowba potection duing 37 % two-phae voltage dip. (a) Line voltage. (b) DVR voltage. (c) Stato voltage. (d) Stato cuent. (e) RSC cuent. (f) Cowba cuent. (g) Mechanical peed. (h) Active and eactive tato powe. (i) Active and eactive DVR powe. (a) (a) (b) (b) (c) (c) (d) (e) (d) (f) (e) (g) (f) 215
(g) (h) (i) Intenational Jounal of Recent Technology and Engineeing (IJRTE) ISSN: 2277-3878, Volume-2, Iue-2, May 2013 2008.ICEMS 2008. Intenational Confeence on, pp. 2316 2321, Oct. 2008. [6] J. Moen and S. de Haan, Shot-cicuit cuent of wind tubine with doubly fed induction geneato, EnegyConveion, IEEE Tanaction on, vol. 22, no. 1, pp. 174 180, Mach 2007. [7] J. Yang, J. Fletche, and J. O Reilly, A eie-dynamic-eitobaedconvete potection cheme fo doubly-fed induction geneato duingvaiou fault condition, IEEE Tan. Enegy Conve., vol. 25, no. 2,pp. 422 432, Jun. 2010. [8] L. H. Hanen, L. Helle, F. Blaabjeg, E. Ritchie, S. Munk-Nielen, H. Bindne, P. Søenen, and B. Bak-Jenen, Conceptual uvey of geneato and powe electonicfo wind tubine, Riø National Laboatoy, Rokilde, Denmak, Tech. Rep.Riø-R-1205(EN), ISBN 87-550-2743-8, Dec. 2001. [9] W. Leonhad, Contol of Electical Dive, 2nd ed. Belin, Gemany: Spinge-Velag, 1996. [10] T. Thiinge and J. Luomi, Compaion of educed-ode dynamic model of inductionmachine, IEEE Tan. Powe Syt., vol. 16, no. 1, pp. 119 126, Feb. 2001. [11] J. Nielen and F. Blaabjeg, A detailed compaion of ytem topologiefo dynamic voltage etoe, IEEE Tan. Ind. Appl., vol. 41, no. 5,pp. 1272 1280, Sep./Oct. 2005. [12] M. H. J. Bollen, Undetanding Powe Quality Poblem Voltage Sag andinteuption. New Yok: Wiley, 2000. [13] S. Maheh,M.Miha, B. Kuma, and V. Jayahanka, Rating and deigniue of dv injection tanfome, in Poc. 23d Annu. IEEE Appl. PoweElecton. Conf. Expo. (APEC), Feb. 2008, pp. 449 455. V. APPENDIX: Fig 7: Simulation of DFIG pefomance with DVR potection duing 37 % two-phae voltage dip. (a) Line voltage. (b) DVR voltage. (c) Stato voltage. (d) Stato cuent. (e) RSC cuent. (f) Cowba cuent. (g) Mechanical peed. (h) Active and eactive tato powe. (i) Active and eactive DVR powe. IV. CONCLUSION Though thi poject the invetigation of the application of the DVR ha hown the ability of the DVR connected to a wind-tubine-diven DFIG to povide uninteuptible faultide-though of gid voltage ditubance/ fault compaed to the ytem unde the cowba potection. The DVR can impove the faulty line voltage, while the DFIG wind tubine can continue it complete nominal opeation and fulfill any gid code equiement without the need to exta potection method. The DVR can be ued to potect aleady intalled wind tubine that do not povide ufficient fault ide-though behavio o to potect any ditibuted load in a mico gid. Simulation eult fo a 2 MW wind tubine unde an aymmetical two-phae gid fault how the effectivene of the popoed technique in compaion to the low-voltage ide though of the DFIG uing a cowba whee continuou eactive powe poduction i poblematic. REFERENCES [1] M. Tili and S. Papathanaiou, A eview of gid code technical equiement fo wind fam, Renewable Powe geneation, IET, vol. 3, no. 3, pp. 308 332, Sept. 2009. [2] S. Seman, J. Niianen, and A. Akkio, Ride-thoughanalyi of doubly fed induction wind-powe geneatounde unymmetical netwok ditubance, Powe Sytem, IEEE Tanaction on, vol. 21, no. 4,pp. 1782 1789, Nov. 2006. [3] S. Fote, L. Xu, and B. Fox, Behaviou and potection of doublyfed induction geneato duing netwokfault, in Powe & Enegy Society Geneal Meeting, 2009. PES 09. IEEE, July 2009, pp. 1 8. [4] L. Peng, B. Fancoi, and Y. Li, Impoved cowba contol tategy of dfig baed wind tubine fo gidfault ide-though, Applied Powe Electonic Confeence and Expoition, 2009. APEC 2009. Twenty-Fouth Annual IEEE, pp. 1932 1938, Feb. 2009. [5] W. Zhang, P. Zhou, and Y. He, Analyi of the by-pa eitance of an active cowba fo doublyfedinductiongeneato baed wind tubine unde gid fault, Electical Machine and Sytem, Mutafa Jawadkadhim Al-Tameemi,wa bon in Baghdad, Iaq on Jan 16,1986.He eceived B.Sc Degee in depatment of electical engineeing at Univeity of Technology,Baghdad,Iaq in 2007.He i cuently M.Tech electical (Powe Sytem)candidate in BhaatiVidyapeeth Deemed Univeity, College of Engineeing,Pune,India. Pof. D.S. Chavan:Ph D (Regiteed), ME (Electical), BE (Electical), DEE Aociate Pofeo, Co-odinato (R&D cell),co-odinato (PH.D.Pogamme management) BhaatiVidyapeeth Deemed Univeity College Of Engineeing Pune 411043. He i puuing Ph D. He eceived ME (Electical)(Powe ytem) Achieved ank cetificate in Pune Univeity fo ME. 216