REAL-TIME LOAD BALANCING AND POWER FACTOR CORRECTION OF THREE-PHASE, FOUR-WIRE UNBALANCED SYSTEMS WITH DSTATCOM

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1 98 Jourl of Mrie iee d Tehology, Vol., No., (14) DO: /JMT REA-TME OAD BAANNG AND POWER FATOR ORRETON OF THREE-PHAE, FOUR-WRE UNBAANED YTEM WTH DTATOM Wei-Neg hg 1 d Ku-Dih Yeh 1, Key words: DTATOM, hrdwre imlemettio, lod omestio, symmetril omoets method. ABTRAT This er resets the desig d imlemettio of distriutio-level stti syhroous omestor (DTATOM) used for the rel-time lod omestio of three-hse, fourwire ower distriutio systems with uled lods. First, use of the symmetril omoets method derives feedforwrd omestio sheme for the DTATOM. The system lok digrm of the DTATOM is the uilt. A omuter simultio is erformed for relimiry verifitio. Filly, hrdwre rototye is uilt usig TM sed otroller. Exerimetl results verify the futiolity of the DTATOM.. NTRODUTON A uled idutive lod i three-hse, four-wire eletri ower distriutio system rodues udesired egtive- d zero-sequee urrets with lggig ower ftor, whih uses dditiol system losses i the ower distriutio system d uled voltge dro o the distriutio lie. The uled voltge dro results i uled voltge o the lod us, ffetig other sesitive lods oeted t the us. The egtive- d zero-sequee urrets re osidered oor ower qulity heome d should e voided whe the uled lod us voltge jeordizes the sesitive lods oeted to the system [8]. od omestio sigifies lig uled lod d orretig the lod ower ftor to uity simulteously. Per sumitted 1/14/1; eted 9/6/13. Author for orresodee: Wei-Neg hg (e-mil: [email protected]). 1 Dertmet of Eletril Egieerig, hg Gug Uiversity, To-Yu, Tiw, R.O.. Dertmet of Eletril Egieerig, hie Hsi Uiversity of iee d Tehology, To-Yu, Tiw, R.O.. od omestio is ritil for eletri ower distriutio system tht feeds lrge ity of uled lods with lggig ower ftors, suh s those i sigle-hse eletril rilwy d eletri r fure systems. ie 197, stti vr omestors (Vs) hve ee widely used i the eletri ower idustry to ehe ower system erformes i res suh s voltge regultio, voltge fliker mitigtio, ower ftor orretio, d uled lod lig [7, 9, 11, 1]. Reetly, euse of rid develomet of high-ower swithig elemets suh s isulted gte iolr trsistors (GBTs) d itegrted gte ommutted thyristors (GTs), stti syhroous omestors (TATOMs) hve ee reogized s the ext geertio of omestors [1, 3, 6, 1, 1-17]. The distriutiolevel stti syhroous omestor (DTATOM) is ewly develoed TATOM used i eletri ower distriutio systems. omred to existig Vs, DTATOMs require less se d re quiker, more omt, d quieter. dditio, reet reserh hs show tht DTATOMs gretly ehe the low-voltge ride-through (VRT) ilities of wid frms [4, 13, 14]. This er rooses DTATOM for the rel-time lod omestio of three-hse, four-wire ower distriutio systems with uled idutive lods. A ew feedforwrd omestio sheme is derived elig the DTATOM to quikly le the uled lod d orret the lod ower ftor to uity simulteously. A three-hse, four-wire uled system iorortig the roosed DTATOM is uilt d simulted with the MATAB/imulik softwre kge. A hrdwre rototye is the uilt for testig. Filly, exerimetl results re give for verifitio.. DTATOM OMPENATON HEME 1. Derivtio of the omestio heme Fig. 1 shows three-hse, four-wire ower distriutio system feedig uled lod. A DTATOM is istlled i rllel with the uled idutive lod. the er, the DTATOM is equivlet to urret-otrolled

2 W.-N. hg d K.-D. Yeh: Rel-Time Uled od omestio y Usig DTATOM 99 V V V V R R R jx jx jx Three-hse, Four-wire Distriutio lie R jx V V V V T T T T W W 1 T V T V Y Uled od T V V d V V d RPWM verter Y Y Fig. 1. A three-hse, four-wire eletri ower distriutio system with uled lod d DTATOM. soure. To omeste uled lod, feedforwrd omestio sheme is used for the DTATOM. The DTATOM otroller detets the lod ower dt, lultes the required omestio urret outut ordig to the lod omestio sheme, d geertes urret i eh hse to omeste the egtive- d zero-sequee urrets used y the uled lod. By usig the DTATOM omestio, the ower soure rovides oly led tive ower. The symmetril omoets method is used to derive the feedforwrd omestio sheme of the roosed DTATOM. As show i Fig. 1, the lie-to-eutrl lod voltges re trsferred to ositive-, egtive-, d zerosequee omoets y usig the symmetril omoets trsformtio mtrix [T], exressed i Eq. (1). V V V V V T V e V V V j(/3) π 1 α α 1 [ ] 1, α 1 α α The lie-to-eutrl voltges re ssumed to e led to simlify the derivtio of the omestio sheme, s exressed i Eq. (). The three-hse lod urrets i the -- referee frme e exressed s Eqs. (3)-(). Alyig the symmetril omoets method trsfers the three-hse lod urrets to the ositive-, egtive-, d zero-sequee omoets, s exressed i Eqs. (6)-(8).,, α α V V V V V V V V d (1) () Y V (3) α Y V (4) αy V () 1 [ ] α α Y Y Y V (6) [ ] Y Y Y V (7) 3 1 [ ] α α Y Y Y V (8) 3 To hieve rel-time lod omestio, the DTATOM should omeste for the imgiry rt of the ositivesequee lod urret d the etire egtive- d zerosequee lod urrets, s exressed i Eq. (9). Thus, the ower soure sulies oly the rel rt of the ositivesequee lod urret. The required omestio urret for the DTATOM e exressed s Eqs. (1)-(1)., m[ ], (9) 1 1 m[ ] (1) 1 α m[ ] α (11) 1 αm[ ] α (1) 1 The lod ower of the three-hse, four-wire system e determied usig the three-wttmeter method, exressed i Eqs. (13)-(1), rerrgig Eqs. (13)-(1) yields Eq. (16), i whih the ositive-, egtive-, d zero-sequee lod urrets re rereseted with lie-to-eutrl tive d retive owers. * ( V ) ( ) [ V 1 ] (13) * ( V ) ( ) [ ( 1 ) ( ) ( α V α α )] (14) ( V ) ( ) α V [ α( ) α ( ) ( )] (1) * P jq 1 1 α α P jq 3V 1 α α P jq (16) Filly, omiig Eqs. (1)-(1) d (16) otis the urrets required y the DTATOM for rel-time uled lod omestio, exressed i Eq. (17).

3 6 Jourl of Mrie iee d Tehology, Vol., No. (14) * V d V d V d Eh Phse Powers d omestio heme lultio i,, Δv d ΔV v v,, P- Hz PF r i i i P i i i r, r, r, r r r si(ωt θ ) si(ωt θ π/3) si(ωt θ π/3) si(ωt) si ωt si(ωt π/3) si(ωt π/3) Hysteresis Bd Regultor i i i * i * i * i T i T i T i 6 - RPWM verter d ystem V d - V d Fig. 3. Blok digrm of the DTATOM otroller. V V V V 38 j 38 j.8 j.3 38 j 1.41 j j 3.64 j j j j j48.3 j j3.37 DTATOM.8 j j48 Uled Uits: od voltge-v, urret-a, imede-ohm, owers-wtt/vr V 17 V 17 1 V 17 1 V W Z,, 3//j37.7 Fig.. A illustrtig exmle for three-hse, four-wire uled lod omestio. where the mtrix [ H ] is: P / V Q/ V P / V [ H ] Q / V P / V Q / V Z Z Z (17) / /3 1/3 1 6 /3 1 / /3 1 6 /3 1 6 /3 1 / llustrtive Exmle Fig. shows exmle of the three-hse, four-wire uled lod omestio usig the roosed DTATOM. Phse- of the lod is oeed to rete uled oertio sorig uled lie urrets with lggig ower ftors. The DTATOM uses Eq. (17) s the omestio sheme for uled lod omestio. dditio, Fig. lists lulted ower flow dt, iludig lie urrets d the owers of the soure, lod, d DTATOM. By usig the DTATOM omestio, the ower soure oly rovides led tive ower. The lultio results i Fig. idite tht eve though the DTATOM does ot rodue tive ower, it rovides th for redistriutig the lod ower flow for lod omestio. 3. DTATOM otroller Blok Digrm Fig. 3 shows the lok digrm of the roosed DTATOM otroller. The rel-time lod dt, P,,, Q,,, d V, re otied usig the fst ower dt detetio method desried i []. The DTATOM is equivlet to urret-otrolled soure i this er. Eq. (17) is used to lulte the omestio urrets. Usig hse-loked loo (P) geertes the referee gle of the lod us voltge. The istteous omestio urret ommd i,, for the lod omestio is otied. A urret-regulted ulse-width modulted (RPWM) iverter is emloyed s the ower stge of the DTATOM to geerte the omestio urret. To miti the d-lik voltge of the DTATOM iverter t ssiged level, suly the ower losses, d hrge the d-lik itors, the DTATOM must sor tive ower from the ower soure. A P- tye feedk otroller regultes the rel-rt urret r of the DTATOM, s exressed i Eq. (18). The tive urret r is the trsferred s rt of the omestio urret ommds, exressed i Eq. (19). The sigl si ωt from the P geertes the rel rt of the

4 W.-N. hg d K.-D. Yeh: Rel-Time Uled od omestio y Usig DTATOM 61 istteous omestio urrets i r,(,, ). * r K vd Ki vddt, vd Vd Vd (18) 1 r, r, 1 π /3 r, 1 π /3 r (19) omiig the omestio urret demds i,, for the lod omestio d the rel-rt urrets i Eq. (19) for the d-lik voltge suort yields the required omestio urret ommd, s exressed i Eq. (). i i i () *,,,, r,(,, ) As show i Fig. 1, voltge devitio V ( Vd Vd) is geerted o the two d-lik itors oeted serilly euse of the otrol error d the iterferee of zerosequee urret. A hysteresis dwidth otrol should e used for lig [], s show i Fig. 3. Usig low-ss filter with dwidth of Hz removes the 6 Hz fudmetl sigl i the d-lik voltge devitio sigl V. A hysteresis d regultor reeives the outut sigl d otrols the hysteresis d of the hysteresis urret omrtor. omiig the urret ommd sigls i *, * * i, i d - T T T tul DTATOM outut urrets i, i, i determies the error urrets. The RPWM otrol sigls re otied usig the hysteresis urret omrtor d re used to otrol the swithig elemets i the DTATOM mi iruit. Thus, the tul omestio urret trk the ommd sigl, d DTATOM oertio is hieved.. MUATON REUT The MATAB/imulik softwre kge is used to relimirily verify the futiolity of DTATOM. Figs. 1 d 3 re used to ostrut the simultio system. The system rmeters re V ll V, 1 mh, Z s.1 j1 Ω,, µf, d f s 6 Hz. A hse-oeed oertio is estlished usig hse- s disture. dditio to three-hse, four-wire system omestio, the roosed DTATOM is effetive i three-hse, three-wire system, thus, simultios re oduted for oth systems. 1. Three-Phse, Four-Wire ystem omestio Fig. 4 shows the simultio results for three-hse, fourwire uled lod omestio. The iitil oertio oit is set t led oertio with P kw, Q kvr, d f.8 lggig. At t.1 s, hse- of the lod is suddely oeed to rete uled lod oertio, s urret (A) urret (A) urret (A) P, Q (kw, kvr) P, Q (kw, kvr) urret (A) Voltge (V) hse-oeed oertio () Three-hse lod urrets i,, () Three-hse omestio urrets i T,, () Three-hse soure urrets i,, Q (d) Powers from the soure Q (e) Powers to the lod 1 i -1 - i (f) Neutrl urret i the soure d lod (g) D-lik voltges resose Fig. 4. Trsiet resose for oeed-hse oertio with the DTATOM omestio.

5 6 Jourl of Mrie iee d Tehology, Vol., No. (14) urret (A) urret (A) urret (A) P, Q (kw, kvr) P, Q (kw, kvr) urret (A) urret (A) hse-oeed oertio () Three-hse lod urrets i,, () Three-hse soure urrets i,, () Three-hse omestio urrets i T,, 1 Q (d) Powers from the soure 1 Q (e) Powers to the lod (f) Positive-sequee omoet urrets (g) Negtive-sequee omoet urrets Fig.. Trsiet omestio resose with the DTATOM omestio. 1 show i Fig. 4(). Phse- lod urret is redued to zero. As show i Fig. 4(), the DTATOM regultes the omestio urrets to uled oertio i orde with the lod omestio sheme. Beuse of the DTATOM omestio, the three-hse soure urrets remi i led d uity ower ftor oditio, s show i Figs. 4() d (d). Although the uled lod geertes eutrl urret, s show i Fig. 4(f), the eutrl urret from the soure is elimited quikly y the DTATOM omestio. Fig. 4(g) shows tht the voltges o the two d-lik itors osttly remi i led oertio. The roosed DTATOM for the three-hse, four-wire uled lod omestio is rid d effetive.. Three-Phse, Three-Wire ystem omestio Fig. shows the omestio results of the DTATOM for three-hse, three-wire uled lod omestio. the simultio, the swithes W1 d W (Fig. 1) re oeed for three-hse, three-wire system oertio. The system is iitilly oerted with 7. kw, Q3.4 kvr, d f.8 lggig. At t.7 s, the hse- of the lod is oeed, s show i Fig. (). Beuse of the DTATOM omestio, the soure urrets re led d orreted to uity ower ftor, s show i Figs. () d (d). Figs. (f) d (g) show the trsiet resoses of the ositive d egtive omoets, resetively, of the soure d lod urrets. The DTATOM resose time is roximtely 4 ms. The simultio results relimirily verify tht the roosed DTATOM is rorite for the rel-time lod omestio of oth three-hse, three-wire d three-hse, four-wire systems with uled idutive lods. V. HARDWARE YTEM ETUP AND EXPERMENTA VERFATON Fig. 6 shows the lok digrm of the imlemeted hrdwre rototye system. A three-hse, four-wire distriutio system is ostruted for verifitio test. Tle 1 lists the system rmeters, whih re the sme s those show i Fig.. A digitl sigl roessor (DP) TM sed otrol system is emloyed s the DTATOM otroller. The otrol rogrm is edited i host P usig lguge. The exeutio file is the dowloded oto the DP-sed otroller for rel-time otrol of the DTATOM. Durig the DTATOM omestio, the three-hse soure urrets, lod urrets, d lod us voltges re otied y the DP d uloded to the host P for lysis. Beuse of the flotig-oit hdlig ility of the DP, the DTATOM is le of rel-time lod omestio. Fig. 7 shows the DTATOM omestio test results. the test, hse-oeed oertio is set s disture. The system egis i led oditio. At t.6 s, hse-oeed oertio is tivted i hse-, whih retes uled lod oertio, d the futiolity of the DTATOM is tested. Figs. 7() to () show the three-hse

6 W.-N. hg d K.-D. Yeh: Rel-Time Uled od omestio y Usig DTATOM 63 v v v v V V d _ V d _ Host P Gtig igls verter Gte Driver X6 T v T v T v T i T i 1 Bits A/D overter PWM urret otroller JTAG TX3 T i * R i, i, * * i Per-Phse P, Q, V Detetio P, Q, P, Q, P, Q, omestio heme lultio T i T i T i Pri- Filter V TM36711-Bsed otroller 1 Bits A/D overter v,, i,, so. Am. Ad Filter V d V d i i i v i i v i i Ts PTs Three-Phse Bled od Z,, v i W Fig. 6. Blok digrm of the DTATOM hrdwre system setu. Tle 1. The hrdwre system rmeters. Power soure Vll V, fs 6 Hz, Z.1 j1ω DTATOM 1 mh, R. Ω,, µ F V 4 V, f khz d PWM od R 3 Ω // X 37.7 Ω, Y-oetio lod urrets, the omestio urrets, d the soure urrets resoses, resetively. At t.6 s, the hse- lod urret suddely dereses to zero, s show i Fig. 7(). After the hse-oeed oertio, the DTATOM three-hse omestio urrets eome uled, s show i Fig. 7(). The three-hse soure urrets re the led, s show i Fig. 7(). Fig. 7(d) shows tht the hse- soure urret osttly remis i hse with the hse- voltge, verifyig uity ower ftor orretio. Fig. 8 shows the ower levels d eutrl urret resoses with the DTATOM omestio. Figs. 8() d () show the ower levels from the soure d to the lod. Although the lod requires retive ower durig oertio, the soure sulies oly tive ower. The retive ower from the soure is osttly redued to zero y the DTATOM. Fig. 8() shows the eutrl urrets of the soure d lod. Beuse of the DTATOM omestio, the eutrl urret from the soure is elimited quikly. The exerimetl results revel tht the roosed DTATOM is highly rorite for the rel-time lod omestio of three-hse, four-wire ower system. V. ONUON This er resets the desig d imlemettio of DTATOM for fst lod omestio i three-hse, urret (A) urret (A) urret (A) Volt., urret (V, A) hse-oeded oertio () Three-hse lod urrets i,, () Three-hse omestio urrets i,, T () Three-hse soure urrets i,, - i v (d) Phse- lod voltge d soure urret Fig. 7. ystem resoses for oeed-hse oertio with the DTATOM omestio. four-wire ower distriutio system with uled idutive lod. To stisfy the rid resose requiremet, ew

7 64 Jourl of Mrie iee d Tehology, Vol., No. (14) P, Q (kw, kvr) P, Q (kw, kvr) urret (A) Q 3 P () Powers to the lod 1. 1 Q () Powers from the soure 1 i - i () Neutrl urrets i the soure d lod Fig. 8. Powers d eutrl urrets resoses with the DTATOM omestio. feedforwrd omestio sheme is emloyed usig the symmetril omoets method, therefore, the modelig d otrol of the DTATOM is similr to tht of trditiol Vs. imultio results from the MATAB/imulik softwre kge show tht the roosed DTATOM hs rid resose time d exerts urte omestio effet. A hrdwre rototye emloyig TM36711 flotigoit DP-sed system is uilt for the fil verifitio test. Exerimetl results show tht the roosed DTATOM is highly effetive for rid lod omestio. DTATOMs my grdully rele stti vr omestors i the er future. Geerl Re rel rt m imgiry rt omlex ower P tive ower Q retive ower V voltge urret Z imede Y dmitte X rete R resiste usrits,, hse-, -, - eutrl T OF YMBO hse zero-sequee omoet 1 ositive-sequee omoet egtive-sequee omoet d diret urret r tive (rel) rt 3 three-hse ll lie-to-lie uersrits soure lod omestio T DTATOM * omlex ojugte or ommd AKNOWEDGMENT The uthors would like to thk the Ntiol iee ouil of Tiw, RO, for fiil suort (rojet umer N98-13-E-18-61). REFERENE 1. Akgi, H., Fujit, H., Yoeti,., d Kodo, Y., A 6.6-kV trsformerless TATOM sed o five-level diode-lmed PWM overter: system desig d exerimettio of -V, 1-kVA lortory model, EEE Trstios o dustry Alitios, Vol. 44, No., (8).. hg, W. N., Fst detetig of sigle-hse ower dt, Proeedig of the oferee of PE 99, igore, (1999). 3. hg, W. N. d Yeh, K. D., Desig d imlemettio of DTATOM for fst lod omestio of uled lods, Jourl of Mrie iee d Tehology, Vol. 17, No. 4, (9). 4. he, W.. d Hsu, Y. Y., otroller desig for idutio geertor drive y vrile-seed wid turie, EEE Trstios o Eergy oversio, Vol. 1, No. 3, (6).. hoe, G. H. d Prk, M. H., Alysis d otrol of tive ower filter with otimized ijetio, EEE Trstios o Power Eletrois, Vol. 4, No. 4, (1989). 6. Gozlez, P. G. d errd, A. G., otrol system for PWM-sed TATOM, EEE Trstios o Power Delivery, (). 7. Gyugyi,., Otto, R. A., d Putm, T. H., Priiles d litios of stti, thyristor-otrolled shut omestors, EEE Trstios o Power Artus d ystems, Vol. 97, (1978). 8. Heydt, G. T., Eletri Power Qulity, trs i iruit Pulitios (1991). 9. Hill, J. E., A rtil exmle of the use of distriutio stti omestor (D-TATOM) to redue voltge flututios, EE Power Eletrois for Reewle Eergy,. 7/1-7/ (1997). 1. Higori, N. G. d Gyugyi,., Uderstdig FAT, EEE Press (). 11. ee,. Y., Wu,. J., d hg, W. N., A omt lgorithm for threehse three-wire system retive ower omestio d lod lig, Eletri Power ystem Reserh, Vol. 8, No., (1). 1. Miller, T. J. E., Retive Power otrol i Eletri ystem, Joh Wiley & os (198). 13. Molis, M., uul, J. A., d Udeld, T., ow voltge ride through of wid frms with ge geertors: TATOM versus V, EEE Trstios o Power Eletrois, Vol. 3, No. 3, (8).

8 W.-N. hg d K.-D. Yeh: Rel-Time Uled od omestio y Usig DTATOM Roer, B., Mih, P., d Thurherr, T., Oertiol exeriees of TATOMs for wid rks, ET Reewle Power Geertio, Vol. 3., No. 3, (9). 1. igh, B. N., h, R., hdr, A., d Al-Hddd, K., tti syhroous omestors (TATOM): Review, ET Power Eletrois, Vol., No. 4, (9). 16. igh, B. N., igh, B., hdr, A., d Kml, A. H., Digitl imlemettio of dved stti omestor for voltge rofile imrovemet, ower-ftor orretio d lig of uled retive lods, Eletri Power ystem Reserh, Vol. 4, (). 17. Wg, B. d they, J. J., DP-otrolled, se-vetor PWM, urret soure overter for TATOM litio, Eletri Power ystem Reserh, Vol. 67, (3).