A New Control for Series Compensation of UPQC to Improve Voltage Sag/Swell

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1 AUT Journl of Modeling nd Simultion AUT J. Model. Simul., 49()(7)7584 DOI:.6/misj A New Control for Series Compenstion of to Improve oltge Sg/Swell M. Torin Esfhni, nd B. hidi Dept. of Eletril Engineering, Shhid Ashrfi Esfhni University, Isfhn, Irn Dept. of Eletril Engineering, Amirkir University of Tehnology, Tehrn, Irn ABSTRACT: oltge sg/swell is one of the most frequent power qulity prolems ffeting power systems with sensitive lods. The unified power qulity onditioner () is ple of mitigting the effet of voltge sg/swell t the lod or point of ommon oupling (PCC). In this pper, new ontrol sed on omining the sg detetion nd voltge injetion estlished on dq frme is proposed. Bsed on vetor ontrol whih n immeditely disover ll the voltge sg in different diretions, the voltge sg is deteted. This method employs the phseloked loop nd positivenegtive sequene to detet the sgs nd the injeted voltge produed y the series onverter. The proposed is investigted in two se studies, inluding different sgs/swells in the min Bus nd forwrdkwrd sgs in the min nd lod Buses. Also, the proposed ontrol n improve other power qulity phenomen, suh s voltge nd urrent hrmonis nd the power ftor in the min Bus. The simultion results show the ury of the proposed method. Introdution The term power qulity (PQ) should e onsidered y vrious spets of power system ehvior. This term inludes disturnes nd distortions. The first tegory onsists of voltge sgs/swells whih re one of the mny power qulity prolems relted to the industril proess. This issue is defined s the shortdurtion redutions in the RMS (root men squre) supply voltge tht n lst from few milliseonds to few yles with typil dip depths rnging from.9 to.5 per unit (pu) of p.u nominl. It hs een shown tht yer on yer voltge sgs using extensive disruption to the industril proess setor in terms of prodution loss [,] hs mde them prtiulrly importnt re of reserh. The seond tegory omprises of voltge nd urrent hrmonis whih n hnge the sinusoidl wveform nd ffet losses, eletri relys, trnsformer, et. On the other hnd, different power systems re eoming highly vulnerle to different power qulity prolems euse of n inrese in nonliner nd sensitive lods nd signifint inrese in the penetrtion level of smll/lrgesle renewle energy systems sed on wind energy, solr energy, fuel ell, et., instlled on the distriution nd the trnsmission levels. Hene, the hne of reting the sg/swell events n e signifintly enhned. It is interesting to stte tht when we tlk out mintining ertin voltge level on Bus, generlly it is first thought of pitors nd Stti r Compenstors (SC). However, they only ontrol the voltge indiretly y ltering the system s effetive impedne. To del with voltge sgs used y fults in trnsmission or distriution systems, the injetion of voltge omined with the supply of tive power is neessry. To ontrol the Review History: Reeived: 8 Otoer 5 Revised: 4 July 6 Aepted: 4 July 6 Aville Online: 7 July 6 Keywords: Power Qulity Sg/Swell Disturnes Synhronous Frme Method power qulity regultions, some types of ompenstion re generted y mens of voltge injetion pility t ll power levels. Dynmi voltge regultor (DR), series tive filter, nd unified power qulity onditioner () fll into this tegory [3]. At the distriution level, is the most ttrtive solution to ompenste severl mjor power qulity prolems. It silly onsists of two voltge soure inverters onneted k to k using ommon d Bus pitor [3]. Different sg detetion methods re investigted in [4]. So fr, different methods hve een suggested for the ontrol of this devie [5]. One of these methods is the independent ontrol of the tive nd retive power in whih the opposing effets re deleted to improve opertion. To improve the ontrol mehnism of the pssge of tive nd retive power nd redue its opposing effet, the dq oordintes re proposed for this purpose. Thus, the tive power is independently ontrolled y the omponents of the d xis nd the retive power is independently ontrolled y the q xis s well. The defiieny of the pplied method is tht the opposing effet of the shunt nd series onverter is not tken into onsidertion [5,6]. Another ontrol method is the ext model in whih the dynmis of ll the swithes re modeled. Sine this model requires muh time for simultion, it is not suitle for dynmi studies nd lowfrequeny flututions whih might lso tke seonds [7,8]. In other types of the models, power ompenstes the voltge fliker, urrent, nd voltge hrmonis in the power systems of eletri r furnes y the use of instntneous power theory method nd the use of tive, retive, nd zero omponents [9,]. Some mehnisms demonstrte ontrol tehnique for oth shunt nd series ompenstor with sinusoidl referenes without the need for hrmoni extrtion to derese the omplexity of the referene genertion of the []. Also, Corresponding uthor, Emil: vhidi@ut..ir 75

2 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj simplified ontrol tehnique is presented in [] for dul threephse topology of unified power qulity onditioner (i) to e used in the utility grid onnetion. The ontrol sheme is sed on n ABC referene frme llowing the use of lssil ontrol theory without the need for oordinte trnsformers nd digitl ontrol implementtion. In generl, to protet the sensitive lods from sg/swell disturne, DR is proposed ut when different lods onsisting of nonliner nd sensitive lod re fed to Busr (most of the time), the is proposed to ompenste the hrmonis nd sg/swell in the min Bus. In summry, three signifint ontrol pprohes to n e found to ontrol the sg on the system: ) tive power ontrol pproh in whih n inphse voltge is injeted through series inverter; ) retive power ontrol pproh in whih qudrture voltge is injeted nd 3) minimum A loding pproh in whih series voltge is injeted t ertin ngle. Among the forementioned three pprohes, the qudrture voltge injetion requires mximum series injetion voltge, wheres the inphse voltge injetion requires the minimum voltge injetion mgnitude. In minimum A loding pproh, the series inverter voltge is injeted t n optiml ngle with respet to the soure urrent. Besides the series inverter injetion, the urrent drwn y the shunt inverter to mintin the d link voltge nd the overll power lne in the network plys n importnt role in determining the overll A loding. In this pper, new ontrol method sed on the omintion of spe vetor nd dq oordintes is proposed so tht the series onverter of is utilized for simultneous voltge sg/swell ompenstion nd lod retive power ompenstion in oordintion with shunt inverter. In this method, t first, the shortterm power qulity phenomen re immeditely deteted nd then ompensted y the series onverter. In ontrst to other methods, the proposed method n improve the sg/swell in oth the lod nd point of ommon oupling (PCC) Bus. Different types of fults re onsidered in the power system nd the performne of is investigted to exmine the proposed method. The simultion results show the ury of the proposed. OPERATION AND BASIC MODEL In this figure, Bus represents PCC Bus. This Bus is the high voltge Bus onneted to Bus, medium voltge Bus, y the TS trnsformer. In ft, Bus supplies the vrious lods, suh s domesti industril lod nd ommeril lods t distriution nd sutrnsmission levels. This Bus is then onneted to Bus 3 whih in ft supplies the sensitive nd nonliner lods in medium voltges. The lods of this Bus re sensitive to voltge sg/swell. For this reson, this Bus is proteted y so tht the voltges sg/swell reted on Bus nnot ffet it. It is ssumed tht voltge sg mesurements t Bus re in ordne with Fig.. By mesuring the sgs (see Fig. ), the region in whih the hs to operte n e deided. In generl, it is required to protet the sensitive lods for pproximte 85% of the mesured sgs. On nlyzing the events, while lso onsidering other prmeters (e.g. event frequeny nd prodution losses), one n give the est solution to the different lods. Until reently, the oost pility hs een defined y using the threephse or the singlephse sg nd the durtion of the sg (e.g. three phse sg 35%, 5ms). Now, with regrd to sensitive lods, the requirement hnges ording to n re in whih the hs to e proteted s shown in Fig. 3. The three or singlephse pility nd its time durtion remin onstnt nd do not define the required energy. As the energy hs een defined now, the protetion re n e inresed over shorter time nd the lrger sgs n e ompensted efore the definition point. This gives the dvntge tht the is proteting muh lrger sg re. Power System LS vjs BUS (PCC BUS) ijs TS (H/M) vjb BUS ijb ijsh TSh(M/L) LSh RSh IgSh IgSh vjsh Cd rious Lods id vd (M/L) vjse TSe IgSe IgSe vinj. vjb3 BUS3 ijl Sensitive & Nonliner Lods Fig.. Studied power system with different lod nd oltge Sg [%] B oltge Sg [%] ms Fig.. Typil voltge sg mesurements Protetion Are.35 Others XTse/ XTse/ ms Fig. 3. Sg re whih the n protet X m Se Series Converter B3 B XTse/ XTse/ X m Se> Series Converter Mximum three phse sg pity Fig. 4. Effet of trnsformer onnetion in stndy oost modes B3 76

3 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj Moreover, the n protet the voltge sg/swell in sensitive lod us, sine the voltge nd urrent hrmonis nnot e injeted into Bus. Also, in Fig., the LS short iruit indutne is in the PCC Bus; Tsh nd Tse trnsformers onnet the shunt onverter nd series onverter to Bus, respetively. The funtion of the shunt onverter is to provide the rel power requested y the series onverter in the ommon DC link so tht it supports the exhnge of rel power resulting from the injetion of the series voltge. The swithes pplied to eh one of the onverters inlude 6 IGBT. Of the resons for the use of IGBT, one n refer to high swithing speed nd no need for ommuttion iruits. The si ide of the series onverter of is to injet dynmilly ontrolled voltge, i.e.se or inj., generted y foredommutted onverter in series, to Bus y mens of ooster trnsformer, e.g. Tse (Fig. ). The momentry mplitude of the three injeted phse voltges is ontrolled so s to eliminte ny detrimentl effets of Bus fult on the lod voltge of Bus 3. This mens tht ny differentil voltges used y trnsient disturnes in the feeder will e ompensted y n equivlent voltge generted y the onverter nd injeted into the medium voltge level through Tse. Most of the time, the series onverter is virtul nd monitors the Bus voltge, i.e. it does not injet ny voltge (Se =) independently of the lod urrent. Therefore, it is suggested tht prtiulr fous e turned to the losses of the series onverter during regulr stndy opertions. These losses inlude trnsformer impedne nd semiondutor devie losses. The ooster trnsformer s low voltge winding is shorted through the onverter in the s stndy mode s shown in Fig. 4. In this mode, the swithing of IGBT does not tke ple, euse the individul legs re triggered so s to estlish shortiruit pth for the onnetion of trnsformer; in this stte, this trnsformer resemles shortedurrent trnsformer. Therefore, only the omprtively lowondution losses of the semiondutors in this urrent loop ontriute to the losses. As shown in Fig. 4, when fult ours in Bus, the series trnsformer injets oost voltge to ompenste the voltge sg in Bus 3. In this mode, it is importnt to ontrol the swithing of IGBTs. As mentioned ove, it is first neessry to detet voltge sg/swell in Bus or Bus 3 nd ompenste for ll of them y series onverter. 3 Proposed Control of The ontrol of hs two prts, inluding shunt ompenstor nd series ompenstor. So fr, different methods hve een proposed for ontrol [6,]. In [,], hs two prts, inluding series nd prllel tive power (AF). The series AF hs urrent loop to ensure sinusoidl grid urrent synhronized with the grid voltge. The prllel AF hs voltge loop to ensure lned regulted lod voltge with low hrmoni distortion. These ontrol loops re independent of eh other sine they t independently in eh tive filter. The d link voltge ontrol is mde in series AF where the voltge loop determines the mplitude referene for the urrent loop in the sme mode of the power ftor onverter ontrol shemes. The ontrol of the shunt ompenstor is sed on [7]. Drwing on Fig., vjsh representing vsh, vsh, nd vsh voltges in different phses is shunt t the entry of the onverter. Also, vd is the DC link voltge nd ijsh represents ish, ish, nd ish urrents in phses,, nd of the shunt onverter exit. On the other hnd, ijb nd vjb represent the urrents nd the threephse voltges t Bus. Bsed on these explntions, the differentil equtions relevnt to shunt onverter n e written s follows: d () LSh i jsh = v jb RSh dt i jsh v jsh, j=,, d C v = f i d d j jsh dt j= where Cd nd vd re the pitor nd the voltge in the DC link, nd RjSh nd LjSh re the resistne nd series indutne with shunt onverter, respetively. fj is the swithing funtion for,, nd phses with vlues of, ±/3 nd ±/3 [7]. The dq frmesed method is proposed for the ontrol of shunt ompenstor of. In this method, different power system equtions re trnsferred from synhronous referene dq frme to d nd q xes y: dq X = T X (3) dq where y: dq T dq T is the mtrix for onverting oordintes to dq π π os θ os θ os θ 3 3 π π = sinθ sin θ sin θ Aording to Eq. (3), this mtrix is lulted y sinusoidl nd osine funtions otined y phseloked loop (PLL) from the power system. Also, X mtrix n e voltge, urrent, swithing funtions, nd other prmeters of the power system. Therefore, y onverting ll equtions of the power system, the shunt ompenstor n e designed s shown in Fig. 5 (for more detils see [7]) In [7], the min im of ontrol is foused on shunt ompenstor, however, in this pper, the ontrol of series ompenstor is the min purpose of ontrol so tht the voltge sg/swell is ompensted y in different onditions. 3 The Proposed Control of Series Compenstor The proposed vetor ontrol topology is depited in Fig. 6. This method is sed on sg detetion nd voltge injetion. The first prt uses the vetor ontrol whose priniple omputes n injetion vetor t ny instnt of time s illustrted in Fig. 6. n protet ll of the lod in Bus (Fig. ) ginst ny phse shift tht might our in mnner tht ll types of voltge sgs n e ompensted. The ore of this method is the phseloked loop (PLL) whih loks synhronous referene frme (d q) to the positivesequene omponent of the supply. The ngle thet used y the synhronous referene frme is lso employed to generte referene vetor. The differene etween the supply nd the referene vetor produes n injeted voltge vetor tht n e used y the seond prt of the series onverter ontroller to produe the pulse ptterns used to ontrol the inverter. As mentioned erlier, the first prt of ontrol in this setion () (4) 77

4 S M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj detets the voltge sg. This is done y lulting d q or d in vetor ontroller. In this method, the three supply phses re onverted into one phsor, i.e. S whih itself onsists of two orthogonl omponents, i.e. α nd β. A synhronous referene frme is loked to S through PLL (Fig. 6) generting vetor d when loked, otherwise d nd q. The vetors re produed s follows: i L i L i L S S S d d to dq PLL oltge Detetion st d d I Ld θ I Lq sin os st Low Pss Filter (s) G d K I K P d s I Ld I Shq d I d I Shd I Shd I Shq K P Shd K I Shd s K I Shd s R Sh K P Shd R Sh / / α β 3/ 3 = α 3 o d osθ = q sinθ U Shd U Shq I Shd ω e L Sh m I Shq Shq sinθ α osθ β ω e L Sh Shd to dq SPWM Ciruits & Pulse Genertion Shunt Converter (5) (6) Sg Detetion Fig. 5. The ontrol of shunt ompenstor & sequenes α oltge etor Genertion β αβ to dq q Phse LokedLoop (PLL) PI Controller ωerror ωreferene ReSettle Integrtor θ β Ld Lq.5 pu d S S to dq Sd Sq dq to Se Se Se SPWM Ciruits & Pulse Genertion Seri Converter Se Se Se q. pu.75 pu d Ref q inj PLL θ sin os θ γ S β α α Min Control Fig. 6. proposed ontrol nd vetor ontrol priniple of series ompenstor in Regrding Fig. 5, if the sg is not ompnied y ny phse shift, then the following expression is true: = =, = (7) s d d q q 3 = = = d This is the esiest kind of voltge sg in terms of detetion nd ontrol where lulting either d or d q will return to the stte of the supply t ny instnt of time nd hene detets whether sg hs tken ple. If the lned sg is ompnied y lned phse jump, then Eq. (7) is no longer vlid, euse the PLL hs to first trk the new ngle. (8) Hene, initilly, = s d q 3 = = = d ( θ ) 3 = = = S (9) () () Clulting d will return the sg depth while monitoring nd mnipulting q will return the initil phse jump informtion. Whether the unlned sg rings out the pility for this method to return the informtion with regrd to the individul supply phses is ompromised. 78

5 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj The supply s seen in oth the fixed αβ nd the synhronous dq frmes my t ny instnt of time pper to e similr to the vetor plot in Fig. 6 when n unlned voltge sg ours. The unlned supply now inludes oth the negtive nd positive sequene dt. The spe vetor S now ontins n osilltion with se frequeny of Hz, nd when viewed in synhronous dq frme loked onto fixed veloity vetor (positive sequene) ppers s pure Hz osilltion in the d nd q omponents [4]. The Synhronous frme omponents, i.e. d nd q osillte with frequeny of Hz s result of the unlned fult or negtive sequene whih mens it n tke up to hlf yle efore minimum d vlue is rehed. Unlike the se of lned fult, there is no diret reltionship etween the vlues of d nd q t ny instnt nd the mgnitudes of the individul min Bus phses; mny different vlues of the min Bus voltge n give the sme d nd q vlues. An dvntge of this method is the reltive ese t whih it n e implemented within prtil reltime ontrol system [5]. Now, the seond prt of the series onverter ontrol system lultes the voltge referene vlues injeted through the series onverter. Sine the system voltge is sinusoidl, the sinusoidl voltge ontrol strtegy is proposed for the ontrol of series setion. In this prt, the series setion is ontrolled in wy tht it ompenstes ll the voltge disturnes so tht the voltge of the two ends of the lod remins s lned threephse sinusoidl voltge. For this purpose, the simultneous referene frme theory is employed. The desired vlue of the line phse voltge in d nd q xes reple low nd highpss filters in this method. The line voltge in this stte is totlly sinusoidl with pproximtely fixed mplitude nd frequeny. The desired voltge expeted y the line is s follows: m = T. = dq Ldq L In the following eqution, m os( ωt θ) π L = m os( ωt θ ) 3 π m os( ωt θ ) 3 L is equl to: Where m is the desired voltge pek vlue for the line nd is the voltge phse ngle lulted y PLL. By reduing the desired vlue of the phse voltge of the d xis ( Ld) from network voltge (sd), ll the disturnes in the d xis re otined.the desired vlue for the line phse voltge in the q xis is equl to zero. In other words, sq expresses ll the disturnes in the q xis. Therefore, the series ompenstion = Sedq Ldq Sdq referene voltge is otined from eqution (4). () (3) (4) Sg Detetion etor oltge Genertion Clulting α nd β y (5) Sequene Detetion Synhronous Referene Frme Clultion y (6) Referene etor Genertion oltge Injetion Fig. 7. Proposed ontrol proedure In this wy, y generting eh disturne in the power system, the effets of tht disturne is generted in the DC link y the series onverter, nd the DC link voltge is lso ontrolled y the series onverter nd its disturne is omitted. 4 Simultion Result Regrding Fig., the voltge level of the power system is medium nd equl to 63 k. Other prmeters re given in [7]. In this setion, two se studies re investigted. In the first, the proposed ontrol system is nlyzed in different onditions nd in the seond, the opertion of in the forwrd nd kwrd fults on Bus is ompred. To perform n nlytil omprison etween the proposed method nd other methods, two methods re investigted nd results re ompred with the proposed method. The first nd the seond method re sed on [3] nd [], respetively. These methods re presented for sg ompensting. Cse study To show the voltge sg phenomenon in phse over time durtions of.5,.7, nd.8 seonds, the singlephse fults hppens for 6 milliseonds piee. Also, to show the phenomenon of voltge swell, lrge pitor nk in.35 to.4 seonds is onneted to phse. To study the power qulity indies in the other two phses in the designed threephse trnsmission system, the phenomenon of voltge sg t instnts of.35 nd.5 seonds eh for 6 milliseonds nd t the instnt of.65 seonds for 8 milliseonds, the singlephse fult to the ground tkes ple first in phse. The intensity of this fult is onsidered different nd t the instnt of.65 seonds the intensity of this fult is very high nd onsidered to e t the rte of voltge utoff so s to etter oserve the effet of. Then, t instnts of.5 nd.65 seonds eh, singlephse ground onnetion tkes ple for 6 milliseonds in phse. Then, from the instnt of.75 to.38 seonds, lrge pitor nk (to indite voltge swell) is onneted to this phse. The effets of these phenomen on the threephse voltges of Bus nd Bus 3 re shown in Fig

6 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj oltge t Phse Without 5 oltge injetion t phse oltge t Phse Without oltge t Phse Without Fig. 8. the sg/swell voltge effet on Buses nd 3: phse phse phse Fig. 9 shows the urve for voltge hnges injeted into Bus 3 in three phses y pling in the suntrnsmission system etween Bus nd Bus 3. Also, the threephse voltges of the power system with onnetion to Bus 3 re depited in Fig.. By oserving the reent urves, it is relized tht hs een le to improve the network voltge very well. On the other hnd, the urve for the threephse voltge profile hnges efore nd fter the presene of in us in different methods is depited in Fig.. By oserving the reent urves, it is relized tht hs een le to improve the network voltge very well, in speil in proposed method. Also, ompenstion of sg/swell in the proposed method in is very etter thn other methods s indited in this figure. On the other hnd, the urrent hnges in us 3 nd in different phses of this us efore nd fter the presene of ompenstor re depited in Fig.. With regrd to Fig., it is oserved tht the urrent hnges re redued in the presene of the ompenstor t instnts of error genertion whih is of gret importne for the oltge injetion t phse oltge injetion t phse Fig. 9. The hnges of injeted voltges into the power system in us 3: phse phse phse improvement of the power system opertion nd design of protetion relys. As previously mentioned, the ontrol of the DC pitor voltge is one of the most importnt units of ontrol system. Fig. 3 depits the DC link pitor voltge hnges in different methods. With regrd to Fig. 3 it is oserved tht the vritions of the pitor voltge hnges in proposed method very well in ordne with the system voltge vritions nd is le to follow it well. Also, the speed performne of DC link is etter thn other methods. Fig. 4 shows the different prmeters of eletri power in us 3. In this diretion, Fig. 4 shows the urve of the hnges of the tive nd retive power injeted into the power system in us. Fig. 4 lso shows the urve of the hnges of power ftor in this us efore nd fter the onnetion of. With regrd to Fig. 4, it is understood tht the designed results in the improvement of the power ftor in the us 3 of the trnsferred system y injeting the required 8

7 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj oltge t Phse With 6 4 I without I With 4 Current (ka) oltge t Phse With oltge t Phse With Fig.. The hnges of the threephse voltges in us fter the onnetion of to the power system: phse phse phse Current (ka) Current (ka) I Without I With I Without I With Fig.. The urrent hnges in different phses of us 3 efore nd fter the onnetion of ompenstor: phse phse phse 8 oltge (pu) Without Method. Method Proposed Method Fig.. Threephse voltge profile hnges efore nd fter the presene of ompring with other methods 6 4 Referene Method Method Proposed method Fig. 3. The DC link pitor voltge hnges ompring with other methods tive nd retive power t the instnts of error genertion. Also, one of the most importnt issues of power qulity in power systems is the hrmoni nlysis issue. Therefore, this setion is devoted to the study of the effets of the designed 8

8 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj Rertive & Ative Power (Mr, MW) Q Injetion P Injetion 5 5 Phse Phse Phse Phse Phse Phse Power Ftor.6.4 PF With PF Without Fig. 4. The eletri power hnges in us 3 t phse hnges of the tive nd retive power injeted into this us power ftor hnges in this us efore nd fter the presene of ompenstor on the improvement of the hrmonis of power system. In this diretion, Tle I shows the voltge hrmonis, urrent, nd totl hrmoni distortion (THD) voltge nd urrent efore nd fter the presene of ompenstor when ll lods in the power system (shown in Fig. ) is existed. The hrmoni vlues in this tle re sed on the hrmonis generted during the error time in eh trnsmission system phse. It should e noted tht the vlues provided in tles I is sed on the mximum vlue of eh prmeter during simultion time. Tle I. The vlues of voltge nd urrent hrmonis nd THD voltge nd urrent in Order Hrmoni Without Phse (% of Fundmentl) With Without With I I THD v.6.9 THD i With regrd to simultion results otined in this setion, it is oserved tht the enjoys the pility of soring the hrmoni in the system in ll the instnts. This ontroller lso improves the totl hrmoni distortion in the system oltge (pu) BUS BUS Fig. 5. the forwrd voltge sg on us 3 voltge hnges on us 3 voltge profile on us nd us 3 Cse study In this se study, the performne of is nlyzed in oth forwrd nd kwrd sgs. The forwrd sgs re defined y reting sg in us nd kwrd sge is ourred on us 3. Fig. 5 shows the effet of forwrd voltge sg on us. The proposed immeditely improve this voltge hnge tht is shown in Fig. 5. the voltge profile on us nd us 3 is indited in Fig. 5. When voltge sg is ourred on us 3 this hnges is defined s kwrd voltge sg whih is shown in Fig. 6. the performne nd the voltge profile re illustrted in Figs. 6 nd 6 respetively. 5 Conlusion In this pper, new ontrol system ws presented for the devies. This ontrol strtegy sed on the sg detetion nd simultneous referene frme for the seprtion of different prmeters of the power system n improve different sgs in different se studies, inluding forwrd nd kwrd sgs. This ompenstor n enhne ll power qulity phenomen 8

9 M. Torin Esfhni nd B. hidi, AUT J. Model. Simul., 49()(7)7584, DOI:.6/misj Phse Phse Phse oltge (pu) BUS BUS Fig. 6. the kwrd voltge sg on us voltge hnges on us voltge profile on us nd us 3 suh s hrmonis (Tle ), different sg/swells in the worst onditions (Fig. 8), nd power ftor (Fig. 4). The dvntges of proposed ontrol re s follows: Immedite detetion of sg/swell voltge in PCC nd lod Bus. Stility of DC link voltge in the worst ondition s sgs with 95% depth. 3 Improvement of the voltge nd urrent hrmonis nd power ftor in the PCC Bus. 4 The simpliity of the proposed ontrol to implement the in tul power systems. The omprison etween the proposed method nd other similr methods n grnt the highperformne speed with minimum error of the proposed. The most importnt dvntge of proposed is simultneously ompenstion urrent/voltge hrmonis nd voltge sgs. Referenes [] C. N. Ho nd H. S. Chung, Implementtion nd performne evlution of fst dynmi ontrol sheme for pitorsupported interline DR, IEEE Trnstions on Power Eletronis, ol. 5, No. 8, pp ,. [] Y. Chen, C. Lin, J. Chen, nd P. Cheng, An inrush mitigtion tehnique of lod trnsformers for the series voltge sg ompenstor, IEEE Trnstions on Power Eletronis,, ol. 5, No. 8, pp.,. [3]. Khdkikr, A. Chndr, A new ontrol philosophy for unified power qulity onditioner () to oordinte lodretive power demnd etween shunt nd series inverters, IEEE Trnstions Power Delivery, ol. 3, No. 4, pp , 8. [4] Ch. Mike Brnes, P. Green, oltge Sg Detetion Tehnique for Dynmi oltge Restorer, IEEE Trnstions on Industry Applitios, ol. 4, No., pp. 3, 4. [5] M. ilthgmuw, Z. H. Zhng, nd S. S. Choi, Modeling, nlysis nd ontrol of unified power qulity onditioner, in Pro. IEEE Hrmon. Qulity Power, 998, pp [6] M. Gon, H. Liu, H. Gu, nd D. Xu, Ative voltge regultor sed on novel synhroniztion method for unlne nd flutution ompenstion, in Pro. IEEE Ind. Eletron. So (IECON), Nov. 5 8, pp ,. [7] M. Torin Esfhni, B. hidi, A Novel Delyless Control of Unified Power Qulity Conditioner to Enhne Power Qulity in Power System, Eletri Power Components nd Systems, ol.4, No. 6, pp.77679, 4. [8] W. C. Lee, D. M. Lee, T. K. Lee, New Control Sheme for Unified PowerQulity CompenstorQ with Minimum Ative Power Injetion, IEEE Trns. Power Del., ol. 5, No., pp ,. [9] X. Zhng, W. Zhng, Y. Lv, W. Liu, Q. Wng, Unified Power Qulity Conditioner with Model Preditive Control, in Pro. 5th Interntionl Conferene Computer Siene Edution, pp ,. [] K. Kwn, P. So, nd Y. Chu, Unified Power Qulity Conditioner for Improving Power Qulity Using MR with Klmn Filters, in Pro. 7th Interntionl Power Engineering Conferene, pp , 5. [] A.Q. Ansri, B. Singh, M. Hsn, Algorithm for power ngle ontrol to improve power qulity in distriution system using unified power qulity onditioner, IET Genertion, Trnsmission & Distriution, ol. 9, No., pp , 5. [] R.J. Millnitz, M. Mezro, A Simplified Control Tehnique for Dul Unified Power Qulity Conditioner, IEEE Trnstions on Industril Eletronis, ol. 6, No., pp , 4. Plese ite this rtile using: M. Torin Esfhni nd B. hidi, A New Control for Series Compenstion of to Improve oltge Sg/Swell, AUT J. Model. Simul., 49()(7)7584. DOI:.6/misj

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