Compensation of Reactive Power and Voltage Fluctuations at Grid Side with Squirrel Cage Induction Generator (SCIG) Wind Farm

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1 ville online t: Speil Issue from 2 nd Ntionl onferene on omputin, Eletril, Eletronis nd Sustinle Enery Systems, 6 th 7 th July 2017, Rjhmundry, Indi ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm nde Venktesh 1 Dr.D.Rvi Kishore 2 1PG Sholr, Deprtment of EEE, Godvri Institute of Enineerin nd Tehnoloy, Rjhmundry, ndhr Prdesh, Indi. 2Professor nd Hed, Deprtment of EEE, Godvri Institute of Enineerin nd Tehnoloy, Rjhmundry, ndhr Prdesh, Indi. To ite this rtile nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm, Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Vol. 03, Speil Issue 04, July 2017, pp STRT Wind Frms (WF) employin squirrel e indution enertor (SIG) diretly onneted to the rid, represent lre perente of the wind enery onversion systems round the world. In filities with moderted power enertion, the WF re onneted throuh medium volte (MV) distriution hedlines. sitution ommonly found in suh sheme is tht the power enerted is omprle to the trnsport pity of the rid. This se is known s Wind Frm to Wek Grid onnetion, nd its min prolem is the poor volte reultion t the point of ommon ouplin (P). Thus, the omintion of wek rids, wind power flutution nd system lod hnes produe disturnes in the P volte, worsenin the Power Qulity nd WF stility. This sitution n e improved usin ontrol methods t enertor level, or ompenstion tehniques t P. In se of wind frms sed on SIG diretly onneted to the rid, is neessry to employ the lst lterntive. ustom power devies tehnoloy (UPS) result very useful for this kind of pplition. In this pper is proposed ompenstion strtey sed on prtiulr UPS devie, the Unified Power Qulity ompenstor (UPQ). ustomized internl fuzzy loi ontrol sheme of the UPQ devie ws developed to reulte the volte in the WF terminls, nd to mitite volte flututions t rid side. The internl ontrol strtey is sed on the mnement of tive nd retive power in the series nd shunt onverters of the UPQ, nd the exhne of power etween onverters throuh UPQ D Link. This pproh inrese the ompenstion pility of the UPQ with respet to other ustom strteies tht use retive power only. Simultions results show the effetiveness of the proposed ompenstion strtey for the enhnement of Power Qulity nd Wind Frm stility. This uide is useful to nyone who would like to ontriute to open soure projets on MTL. Open Soure is Gret Pltform for MTL Enthusists to shre ide. Thnk you for your willinness to ontriute. Keywords: tive power, Retive power, volte flututions, Squirrel e Indution Genertor, Wind Frm. opyriht 2017 Interntionl Journl for Modern Trends in Siene nd Tehnoloy ll rihts reserved. I. INTRODUTION With the inrese in popultion nd industriliztion, the enery demnd hs inresed sinifintly. However, the onventionl enery soures suh s ol, oil, nd s re limited in nture. Now, there is need for renewle enery soures for the future enery demnd [1].The other min dvntes of this renewle soure re eo-friendliness nd 1 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

2 nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm unlimited in nture [2]. Due to tehnil dvnements, the ost of the wind power produed is omprle to tht of onventionl power plnts. Therefore, the wind enery is the most preferred out of ll renewle enery soures [3]. In the initil dys, wind turines hve een used s fixed speed wind turines with squirrel e indution enertor nd pitor nks. Most of the wind turines re fixed speed euse of their simpliity nd low ost [4]. y oservin wind turine hrteristis, one n lerly identify tht for extrtin mximum power, the mhine should run t vryin rotor speeds t different wind speeds. Usin modern power eletroni onverters, the mhine is le to run t djust le speeds [5]. Therefore, these vrile speed wind turines re le to improve the wind enery prodution [6]. Out of ll vrile speed wind turines, douly fed indution enertors (DFIGs) re preferred euse of their low ost [7]. The other dvntes of this DFIG re the hiher enery out put, lower onverter rtin, nd etter utiliztion of enertors [8]. These DFIGs lso provide ood dmpin performne for the wek rid [9]. Independent ontrol of tive nd retive power is hieved y the deoupled vetor ontrol lorithm presented in [10] nd [11]. This vetor ontrol of suh system is usully relized in synhronously rottin referene frme oriented in either volte xis or flux xis. In this work, the ontrol of rotor-side onverter (RS) is implemented in volte-oriented referene frme. Grid ode requirements for the rid onnetion nd opertion of wind frms re disussed in [12]. Response of DFIG-sed wind enery onversion system (WES) to rid disturne is ompred to the fixed speed WES in [13]. s the wind penetrtion in the rid eomes sinifint, the use of vrile speed WES for supplementry jos suh s power smoothenin nd hrmoni mitition re ompulsory in ddition to its power enertion. This power smoothenin is hieved y inludin super mneti enery store systems s proposed in [14]. The other uxiliry servies suh s retive power requirement nd trnsient stility limit re hieved y inludin stti ompenstor (STTOM) in [15]. distriution STTOM (DSTTOM) oupled with fly-wheel enery store system is used t the wind frm for mititin hrmonis nd frequeny disturnes [16]. However, the uthors hve used two more extr onverters for this purpose. super pitor enery store system t the d link of unified power qulity onditioner (UPQ) is proposed in [17] for improvin power qulity nd reliility. In ll ove methods [15] [17], the uthors hve used seprte onverters for ompenstin the hrmonis nd lso for ontrollin the retive power. However, in lter stes, some of the reserhers hve modified the ontrol lorithms of lredy existed DFIG onverters for mititin the power qulity prolems nd retive power ompenstion [18] [26]. The hrmonis ompenstion nd retive power ontrol re hieved with the help of existin RS [18] [23]. Therefore, hrmonis re injeted from the RS into the rotor windins. This retes losses nd noise in the mhine. These different hrmonis in rottin prt my lso rete mehnil unlne. Moreover, oth retive power ompenstion nd hrmoni ompenstion re hieved in ll the se methods usin RS ontrol. These methods inrese the RS rtin. In [24] nd [25], hrmoni ompenstion nd retive power ontrol re done usin GS. Therefore, the hrmonis re not pssin throuh mhine windins in ll these ses. TLE I URRENT DISTORTION LIMITS FOR GENERL DISTRIUTION SYSTEMS IN TERMS OF INDIVIDUL HRMONIS ORDER (ODD HRMONIS) To deshini nd Emnuel [26] hve ompred three different ontrol lorithms nd finlly onluded tht omined modultion of oth RS nd GS re needed for ompenstin the hrmonis nd ontrollin the retive power. However, the uthors hve used diret urrent ontrol of GS. Therefore, hrmoni ompenstion is not so effetive nd totl hrmoni distortion (THD) is not less thn 5% s per IEEE 519 stndrd iven in TleI. The uthors hve lso not verified simultion results experimentlly. n indiret urrent ontrol tehnique is simple nd shows etter performne for elimintin hrmonis s ompred to diret urrent ontrol [27] [30]. In this work, new ontrol lorithm for GS is proposed for ompenstin hrmonis produed y nonliner lods usin n indiret 2 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

3 nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm urrent ontrol. RS is used for ontrollin the retive power of DFIG. The other min dvnte of proposed DFIG is tht it works s n tive filter even when the wind turine is in shutdown ondition. Therefore, it ompenstes lod retive power nd hrmonis t wind turine stllin se. oth simultion nd experimentl performnes of the proposed interted tive filter-sed DFIG re presented in this work. The dynmi performne of the proposed DFIG is lso demonstrted for vryin wind speeds nd hnes in unlned nonliner lods t point of ommon ouplin (P). The volte-soure onverter is widely used s n interfe for the renewle enery systems efore they re linked to the rid like in the photovolti nd wind power system ses, with its dvntes in fully ontrol of d-link volte, tive nd retive power, s well s power ftor [1] [3]. rid filter is normlly introdued to void the pulse width modultion rrier nd side-nd volte hrmonis ouplin to the rid tht n distur other sensitive lods or equipment. For the mewtt-level wind power onverter, due to the quite low swithin frequeny of the power swithin devies (usully severl kilohertz), simple filter indutor onsequently eomes ulky, expensive, nd it my lso rin poorer dynmis into the system [4] [6]. In order to fulfill the modern rid odes [7] [9], the wind turine system is urrently required to ehve more like trditionl power soure (e.., synhronous enertor), whih implies tht the wind turine system should hve the pility of retive power support. Due to the douly fed mehnism of the douly fed indution enertor (DFIG)-sed wind turine system, the retive power n e supported either y the rid-side onverter (GS) or the rotorside onverter (RS). If the retive power is provided y the GS, in the se of the onstnt d-link volte, the modultion index is losely relted to the filter indutne, nd it will inrese very fst to overmodultion, espeilly when overexited (OE) retive power is needed [10]. There re two wys to del with this issue inrese the d-link volte, whih ives hiher swithin loss nd power rtin, or desin n optimized rid filter. esides, if smll mount of retive power is demnded y the trnsmission system opertor, it is lso of interest to ompre the loss of the whole DFIG system, s the retive power supported y the GS only ffets the loss of the GS, while the retive provided y the RS not only influenes the loss of the RS, ut lso the loss of the enertor itself. Then, the nnul enery loss of the wind turine system nd ost of the retive power n e lulted sed on the nnul wind profile t different ompenstion shemes. Fi1:Typil DFIG onfiurtion in wind turine system (GS: rid-side onverter; RS: rotor-side onverter). II. WIND TURINES If the mehnil essentilness is used prtiulrly y equipment, for instne, pump or rushin stones, the mhine is y nd lre lled Windmill. wind turine is mhine for hnin over the enine impertiveness in wind into mehnil essentilness. If the mehnil essentilness is then hned over to ontrol, the mhine is known s wind enertor. s wind turines inrese in size nd rise to more onspiuous sttures to misuse hiher impertiveness winds, their towers require more mterils nd inlude reter rte of the wnder's ost. Vile dvnement tehniques n uprde mteril sums nd derese osts. In this prt territory 3.2 inspet out the sorts of wind turines like level enter wind turines, vertil enter wind turines nd their purposes of interest nd loks. Zone 3.3 looks t the fore in the wind. Territory 3.4 is out workin of wind turine. Portion 3.5 is nlyzes out self-exittion of wind turine retin frmework. Finlly Setion 3.6 dirms the prt. 2.1 Types of wind turines Wind turines re requested into two enerl sorts: even turn nd vertil enter point. level enter point mhine hs its leedin edes turnin on enter prllel to the round. vertil turn mhine hs its edes turnin on enter point inverse to the round. There re different ville dirms for oth nd eh sort hs ertin entrl fouses nd shortomins. Then in, differentited nd the even enter point sort, not lot of vertil turn mhines re ville finnilly. 3 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

4 nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm III. DOULY-FEDINDUTION GENERTOR s the penetrtion of lre sle wind turines into eletri power rids ontinues to inrese, eletri system opertors re plin reter demnds on wind turine power plnts. One of the most hllenin new interonnetion demnds for the douly fed indution enertor (DFIG) rhiteture is its ility to ride throuh short-term low or zero volte event t the point of ommon ouplin (P), resultin from fult on the rid. Durin extreme volte ss hih per unit urrents nd shft torque pulstions our unless mititin mesures re tken. Low volte ride throuh requirements were first proposed y Germn eletri trnsmission opertors E.ON nd VE-T in2003.in the U.S. FER order 661 stipultes tht the wind turine must remin onneted to the rid nd provide fultlerin urrent in the event tht the volte t the hih side of the step up trnsformer to the trnsmission system drops to zero volts for mximum of nine yles, s the result of three phse fult.similr low/zero volte ride throuh requirements hve evolved in most Europen ountries, eh with vryin speifitions on minimum volte level nd requirin provisions of rel or retive power durin fult events While mny rid odes lso stipulte ride throuh of sinle nd two-phse fults, only lned fults re onsidered in this pper. In onventionl DFIG wind turine the mhine sttor windins re onneted to the rid P vi olletion nd/or trnsmission trnsformers nd exited t the rid frequeny. The rotor windins of the DFIG re onneted to n onverter ommonly referred to s the mhine side onverter (MS). The side of seond d onverter, ommonly referred to s the rid side onverter (GS), is onneted in prllel with the mhine sttor windins nd P.Severe volte ss nd the resultin sttor flux response ple sinifint eletril stress on the MS nd mehnil stress on the erox. In the sttionry frme the sttor flux is equl to the interl of the sttor volte minus sttor resistive drop. n rupt sttor volte hne produes onstnt d omponent of sttor flux in proportion to the volte drop This d sttor flux omponent ppers s n osilltory eletromneti field(emf) when trnslted into the synhronous nd rotor referene frmes.deep ss nd orrespondinly lre EMF in the rotor referene frme use the MS to o into over-modultion, resultin in loss of rotor urrent reultion.the unontrolled rotor urrents n exeed the semiondutor devie rtins nd result in dme the MS. In ddition, this ommonly preipittes hih trnsient sttor urrents nd trnsient torque spikes.severl options hve een proposed to improve low volte FIG ride throuh. Two modifition to the rotor iruit inludin the ddition of either n silion ontrolled retifier(sr) rotor rowr iruit [or three phse retifier nd modulted resistive lod hve demonstrted improvement in the DFIG ride-throuh pility s n lterntive, rief disonnetion of the sttor windins durin volte s vi n SR stti swith hs lso een shown to redue torque nd urrent spikes for ss to 15% of nominl. modified rotor urrent ontrol method hs een shown to protet the MS for wind turine terminl volte down to out 30% of nominl, with residul torque spikes nd osilltions.from n lternte perspetive, the uthors of first proposed usin n inverter onneted to the Y point of the DFIG, In series with the sttor windins, for the purposes of dmpin synhronous frme sttor flux osilltions. The presene of the onverter in series with the sttor windin llows diret hndle with whih to ess the sttor flux stte vrile. The use of series onneted rid side onverter ws first onsidered for the purposes of volte s ride riefly in, ut it properties nd limittions were not studied in depth to develop definitive solution. Further explortion of the series rid side onverter DFIG rhiteture,reveled exellent potentil for volte s ride throuh ut lso short omins in power proessin pility. unified DFIG rhiteture in whih the series rid side onverter is prtnered with prllel rid side retifier is presented s n lterntive for oth DFIG wind turine power proessin nd roust volte s ride throuh. IV. ONTROL STRTEGY OF THE RS In ses of non severe fults, the fult urrent provided y the DFIG onsists of the sttor fult urrent nd the rid side fult urrent of the rid side onverter (GS). However, sine the pity of GS is only 25 30% of the rted pity of wind turine, the rid side fult urrent provided y the GS is so smll tht it hs limited influene on the fult urrent provided y the DFIG. Hene, in this pper, only the dynmi response hrteristis nd sttor fult urrent re tken into 4 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

5 m E m E om om nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm onsidertion. The synhronous dq referene frme is hosen to model the DFIG sed on the fifth-order two-xis representtion, nd the model of DFIG is ommonly known s Prk model [15]. Disrete, s = 5e-005 s powerui N Prormmle V-I Mesurement2 Volte Soure Series RL rnh Series RL rnh2 V-I Mesurement1 Series RL rnh1 reker V-I Mesurement Sine Wve dd 12 lok onstnt 1 km line 1 575_1 (575 V) Swith n2 0.69/33e3 630KV wind1 Wind wind (m/s) [Trip_WT1] Trip trip Wind Turine 1 Indution Genertor (Phsor Type) 170 kvr Series RL rnh3 Timer Series RL Lod1 Fi2: Frmework of power loss estimtion. () Retive power is injeted y the RS. () Retive power is injeted y the GS. Series RL Lod V. SIMULTION RESULTS Fi: WES Without UPQ -K- Gin Disrete, Ts = 5e-005 s Genertor speed (pu) powerui 45 onstnt1 Pith nle (de) Tm (pu) Wind speed (m /s) Wind Turine m Tm <Eletromneti torque Te (N*m)> <Rotor speed (wm)> Te wrs Timer rotorpulses From v + Vd Goto -T- From4 - - pulse1 From14 mesurements Susystem i + - urrent Mesurement pulse2 Is Goto3 Fi: tive nd Retive Power t Grid From15 Fi: Simultion iruit of onventionl Wind System Fi: Grid nd Wind turine volte Disrete, Ts = 5e-005 s. powerui Fi: Lod urrent Series RL rnh Sine Wve dd 12 lok onstnt Swith wind1 [Trip_WT1] Wind wind (m/s) Trip trip N Prormmle Volte Soure V-I Mesurement2 Series RL rnh2 V-I Mesurement1 Series RL rnh1 reker UPQ V-I Mesurement 1 km line 1 575_1 (575 V) n2 0.69/33e3 630KV 170 kvr Wind Turine 1 Indution Genertor (Phsor Type) Series RL rnh3 Timer Series RL Lod1 Series RL Lod ontrollin Fi: Wind Enery onversion System with UPQ Fi: SGIG Torque 5 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

6 nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm Fi: tive nd Retive Power t Grid Fi: Grid nd Wind turine volte y oservin the Grid onneted wind enery onversion system with nd without UPQ. The tive power nd retive vrition is veryless with the UPQ. Similrly the volte flututions lso very less. VI. ONLUSION The GS ontrol lorithm of the proposed DFIG hs een modified for supplyin the hrmonis nd retive power of the lol lods. In this proposed DFIG, the retive power for the indution mhine hs een supplied from the RS nd the lod retive power hs een supplied from the GS. The deoupled ontrol of oth tive nd retive powers hs een hieved y RS ontrol. The proposed DFIG hs lso een verified t wind turine stllin ondition for ompenstin hrmonis nd retive power of lol lods. This proposed DFIG-sed WES with UPQ hs een simulted usin MTL/Simulink environment, nd the simulted results re verified. Dynmi performne of this proposed GS ontrol lorithm hs lso een verified for the vrition in the wind speeds nd for lol nonliner lod. REFERENES [1].. Rokhill, M. Liserre, R. Teodoresu, nd P. Rodriuez, Gridfilter desin for multi-mewtt medium-volte volte-soure inverter, IEEE Trns. Ind. Eletron., vol. 58, no. 4, pp , pr [2] M. Liserre, F. ljer, nd. Dell quil, Step-y-step desin proedure for rid-onneted three-phse PWM volte soure onverter, Int. J. Eletron., vol. 91, no. 8, pp , Jn [3] M. Liserre, F. ljer, nd S. Hnsen, Desin nd ontrol of n LLfilter- sed three-phse tive retifier, IEEE Trns. Ind. ppl., vol. 41, no. 5, pp , Sep [4] Z. hen, J. M. Guerrero, nd F. ljer, review of the stte of the rt of power eletronis for wind turines, IEEE Trns. Power Eletron., vol. 24, no. 8, pp , u [5] F. ljer, Z. hen, nd S.. Kjer, Power eletronis s effiient interfe in dispersed power enertion systems, IEEE Trns. Power Eletron., vol. 19, no. 5, pp , Sep [6] M. Liserre, R. rdens, M. Molins, nd J. Rodriuez, Overview of multi-mw wind turines nd wind prks, IEEE Trns. Ind. Eletron., vol. 58, no. 4, pp , pr [7] Requirements for Offshore Grid onnetions, E. ON-Netz, Dusseldorf, Germny, pr [8] M. Tsili nd S. Ppthnssiou, review of rid ode tehnil requirements for wind frms, IET Renewle Power Gener., vol. 3, no. 3, pp , Sep [9]. mho, M. still, J. Miret, R. Guzmn, nd. orrell, Retive power ontrol for distriuted enertion power plnts to omply with volte limits durin rid fults, IEEE Trns. Power Eletron., vol. 29, no. 11, pp , Nov [10] D. Zhou, F. ljer, M. Lu, nd M. Tonnes, Therml ehvior optimiztion in multi-mw wind power onverter y retive power irultion, IEEE Trns. Ind. ppl., vol. 50, no. 1, pp , Jn [11] S. Muller, M. Deike, nd R. W. De Donker, Douly fed indution enertor systems for wind turines, IEEE Ind. ppl. M., vol. 8, no. 3, pp , My [12]. Nel nd R. W. De Donker, Systemti desin of EMI-filters for power onverters, in Pro. onf. Re. Ind. ppl. onf., 2000, pp [13] R. Teodoresu, M. Liserre, nd P. Rodriuez, Grid onverters for Photovolti nd Wind Power Systems. Hooken, NJ, US: Wiley, [14] R. Pen-lzol, M. Liserre, F. ljer, R. Sestin, J. Dnnehl, nd F. W. Fuhs, nlysis of the pssive dmpin losses in LL-filtersed rid onverters, IEEE Trns. Power Eletron., vol. 28, no. 6, pp , Jun [15] W. Wu, Y. He, T. Tn, nd F. ljer, new desin method for the pssive dmped LL nd LLL Filter-sed sinle-phse rid-tied inverter, IEEE Trns. Ind. Eletron., vol. 60, no. 10, pp , Ot [16] D. Zhou, F. ljer, M. Lu, ndm. Tonnes, Therml ylin overview of multi-mewtt two-level wind power onverter t full rid ode 6 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017

7 nde Venktesh nd Dr.D.Rvi Kishore, ompenstion of Retive Power nd Volte Flututions t Grid Side with Squirrel e Indution Genertor (SIG) Wind Frm opertion, IEEJ J. Ind. ppl., vol. 2, no. 4, pp , Jul [17] S. Enelhrdt, I. Erlih,. Feltes, J. Kretshmnn, nd F. Shewre, Retive power pility of wind turines sed on douly fed indution enertors, IEEE Trns. Enery onvers., vol. 26, no. 1, pp , Mr [18] R. Tkhshi, H. Ihit, J. Tmur, M. Kimur, M. Ihinose, M. Futmi, nd K. Ide, Effiieny lultion of wind turine enertion system with douly-fed indution enertor, in Pro. Int. onf. Eletr. Mh., 2010, pp [19] S. Wee, M. Shin, nd D. Hyun, Sttor-flux-oriented ontrol of indution motor onsiderin iron loss, IEEE Trns. Ind. Eletron., vol. 48, no. 3, pp , Jun [20]. G. o-khlil, H. Prk, nd D. Lee, Loss minimiztion ontrol for douly-fed indution enertors in vrile speed wind turines, in Pro. 33rd nnu. onf. Ind. Eletron. So., 2007, pp [21]. Sintmren, F. ljer, nd H. Wn, omprehensive evlution on effiieny nd therml lodin of ssoited Si nd Si sed PV inverter pplitions, in Pro. nnu. onf. Ind. Eletron. So., 2013, pp [22] Wind Turines Prt I: Desin Requirements, 3rd ed., 2014, IE Vests wesite. (2014). [Online]. ville: wind-power-plnts/wind-projet-plnnin/sitin/w indlsses. spx?tion=3#/vests-univers) 7 Interntionl Journl for Modern Trends in Siene nd Tehnoloy, Volume 3, Speil Issue 4, July 2017