Power quality improvement using Hardware Implementation of PI Controlled Three-Phase Shunt Active Power Filter

Transcription

1 Power qulity improement using Hrdwre Implementtion of PI Controlled Three-Phse Shunt Atie Power Filter ISMAIL Ghdbne, MOHAMED TOUFIK Benhoui Abstrt The simultion nd experimentl study of Proportionl Integrtor ontrolled DC bus oltge of three phse shunt tie power filter (APF), to improe power qulity by ompensting hrmonis nd retie power required by nonliner lod is proposed. The lgorithm used to identify the referene urrents is bsed on the Self Tuning Filter (STF). PWM signl genertion is bsed on hysteresis ontrol omprtors to obtin the swithing signls. Vrious simultion nd experimentl results show the fesibility nd the effetieness of the designed tie filter Keywords Hrmonis, shunt tie filter, Proportionl Integrtor, totl hrmoni distortion I. INTRODUCTION The stndrd norms imposed by utilities fore the users to omply with the hrmonis injeted into the network. Also, n dequte retie power support is importnt to improe the eletril grid stbility. As it hs been obsered for reent dedes, n inresing prt of the generted eletri energy is onerted through retifiers, before it is used t the finl lod. In power eletroni systems, espeilly, diode nd thyristor retifiers re ommonly pplied in the front end of DC-link power onerters s n interfe with the AC line power (grid) Some of the power qulity problems n be soled by utilizing shunt tie power filters [1]-[11]. Howeer, the ost of shunt tie filters is reltiely high nd they re not preferble for lrge-sle system sine the power rting of the shunt tie filter is diretly proportionl to the lod urrent to be ompensted [1]-[1]. In ddition, their ompenstion performne is better only under urrent hrmonis type of lods thn the oltge hrmonis type. To redue the system ost, shunt hybrid power filter hs been proposed nd used []-[5]. Power eletronis deies he been widely used in reent yers; while they re onenient in use they use seerl power pollutions just like eletril hrmonis nd low power ftor. In high power systems, most eletril deies use three-phse symmetril power system. But in medium nd smll power system, single-phse eletroni equipments re widely used in domesti, edutionl nd ommeril pplines, suh s omputers, ommunition equipments nd eletroni lighting bllsts, et. This work ws supported in prt by the Eletril Engineering lbortory, Reserh enter, uniersity of Biskr, 7000 Algeri. I Ghdbne is with the Eletril Engineering lbortory, Reserh enter, uniersity of Biskr, 7000 Algeri. (ghdbneteh@gmil.om). B. M.Toufik is with the Eletril Engineering lbortory, Reserh enter, uniersity of Biskr, 7000 Algeri. (benhouit@yhoo.fr). These equipments normlly he diode retifier to onert eletriity to d nd filter by huge pitor.. These equipments behe like nonliner lods, generting hrmonis nd use eletromgneti omptibility problems. For the deies with n lterntie input suh s: retifiers, A oltge ontrollers, indiret frequeny onerters..., the we shpe of the bsorptie urrent of the network is non-sinusoidl. In ddition to the fundmentl omponent, this weform presents hrmoni ontents whih re, in ertin ses, ery importnt. These hrmonis re propgted from the lod towrds the network nd generte hrmoni oltge drops whih re dded to the fundmentl omponent of the oltge deliered by the network. The result is form of ffeted we, whih ontins lso of hrmoni ontents; this ffeted we n, s mentioned before, use serious problems of eletromgneti omptibility. Mny solutions he been studied in the literture to mitigte the hrmoni problems, suh s filtering (pssie, tie, nd hybrid) with rious topologies (shunt, series or both) [6] Industril nd domesti equipments tully use lrge riety of power eletroni iruits suh s swith mode power onerters, djustble speed dries, retifiers nd dimmers. These ones led to signifint energy sings nd produtiity benefits. But unfortuntely, they lso present non-liner impedne to the supply network nd destroying equipments nd disturbnes of ommunition equipments nd preision instruments [1]. So, it is neessry to deelop tehniques to redue ll the hrmonis s it is reommended in the IEEE The first pproh onsists in the design of LC filters. But, pssie filters re not well dpted s they do not tke into ount the time rition of the lods nd the network [1], []. They n lso led to resonne phenomen. The tie power filter (APF) n sole the problems of hrmoni nd retie power simultneously. The theories nd pplitions of tie power filters he beome more populr nd he ttrted gret ttention sine two dedes go. Sine its introdution some twenty yers go, the Atie Power Filter APF presents good solution for disturbne tretment, prtiulrly for hrmoni urrents nd/or oltges. APF is n up-to-dte solution to power qulity problems. The shunt APF llows the ompenstion of urrent hrmonis nd unblne, together with the power ftor orretion, nd n be muh better solution thn the onentionl pproh (pitors nd pssie filters) The performne of the APF is determined by the kind of ontrol used. It is more emphsized when the oltges of eletril network ontin hrmonis nd/or re unblned. Moreoer, the Self Tuning Filter STF is proposed for extrting hrmoni urrents insted of lssil hrmonis 94

2 extrtion bsed on High Pss or Low Pss Filters [4], [5]. The three phse urrents/oltges re deteted using urrent/oltge sensors. The inerter urrents re ontrolled by using hysteresis omprtors,. The hysteresis ontrol is hrterized by its simpliity nd its intrinsi speed.. [1][3][7] II. SYSTEM CONFIGURATION fig.1 presents the shunt tie filter topology bsed on three-phse oltge soure inerter, using IGBT swithes, onneted in prllel with the three-phse three-wire system through three indutors L f. the pitor is used in the D side to smooth the D terminl oltge. the nonliner lod is three-phse diode retifier supplying RL lod. this lod genertes hrmoni urrents in the supply system. the proposed ontrol strtegy n be diided in two prts. the first prt is the hrmoni isoltor (referene urrent genertion). it onsists in generting the hrmoni urrent referenes nd uses STF insted of HPF or LPF usully used in the lssil instntneous rel nd imginry power theory, first proposed by H. kgi [5]. this hrmoni isoltor will be implemented into DSPACE system (ds1104 prototyping rd) in the experimentl study. the seond prt is the urrent ontrol of the power onerter. this ontroller genertes the suited swithing pttern to drie the igbts of the inerter by using modulted hysteresis urrent ontroller. in the experimentl study, this ontroller is implemented into n nlogue rd. pitor C is used s energy soure. The pitor is initilly hrged through the diodes of the inerter. The nonliner lod onsists of three-phse diode bridge retifier feeding n R-L lod. This lod genertes hrmoni urrents in the supply system. The proposed ontrol strtegy n be diided in three prts. The first prt is the hrmoni isoltor (referene urrent genertion). It onsists in generting the hrmoni urrent referenes using the STF. The identifition method of hrmonis used is the method of instntneous power. This hrmoni isoltor will be implemented into dspace system (dspace-1104 prototyping rd) in the experimentl. The seond prt is the urrent ontrol of the power onerter. The ontrol genertes the suited swithing pttern to drie the IGBTs of the inerter using hysteresis urrent ontroller. In the experimentl study, the hysteresis ontroller is implemented on n nlogue rd deeloped in our lbortory. Finlly The DC pitor oltge is regulted using the SMC. The sliding surfe is designed by imposing desired dynmi behior, whih llows us to determine the prmeters in designing the SMC. V d L s I s V s I L L L L d R d n L s I s V s I L L L L d V V b I L i Lb I F Diode Retifier A/D R d L F I F Diode Retifier Hrmoni Isoltor DSPACE (DS1104 rd) Atie filter L F 6 ontrol signls D/A i f,i fb Atie filter i f ref,i fb ref, i f ref Anlogue rd (hysteresis Current ontroller) Fig 1. Power system onfigurtion. The proposed system onfigurtion of shunt tie power filter is shows in Fig.. Three-phse oltge soure inerter using IGBT swithes, onneted in prllel with the AC threephse three-wire system through three indutors Lf. The Fig. Experimentl system 95

3 III-HARMONIC ISOLATION Akgi [1] proposed theory bsed on instntneous lues in three-phse power systems with or without neutrl wire, nd is lid for stedy-stte or trnsitory opertions, s well s for generi oltge nd urrent weforms lled s Instntneous Power Theory or Atie- Retie (p-q) theory whih onsists of n lgebri trnsformtion (Clrke trnsformtion) of the three-phse oltges in the -b- oordintes to the - oordintes, followed by the lultion of the p-q theory instntneous power omponents by eliminting the DC omponent of the instntneous tie power (orresponding to the fundmentl omponent of lod urrent) using seletie Filter STF, so the hrmoni omponents n be identified. Figure 3 shows the modified sheme for the identifition of referene urrents during simultneous ompenstion of hrmoni urrents nd retie power using the method of instntneous power by using STF 1 1/ 1/ i / 3 / In the presene of hrmonis, the power is omposed of three prts: tie (P), retie (Q) nd deformed (D) s shown by the following eqution: (3) S P + Q + D The instntneous tie power, denoted P (t) is defined by the following eqution: P ( t) i + i + s s sb sb s i s L Lb LC () (4) Cn be written in the sttionry referene: P ( t ) i + s s s i s (5) Fig. 3: The method of instntneous tie nd retie power This method is bsed on mesuring the instntneous three-phse ribles present on the grid with or without zerosequene omponents. This method is lid both in stedystte phse. In this ontrol lgorithm (Figure ), mesurements of oltges nd urrents expressed s three phse (b) re onerted to two-phse system (-) is equilent to using the trnsform from Conordi leing the power inrint: 1 1/ 1/ 3 0 3/ 3/ s sb s (1) Similrly the instntneous imginry power n be written s follows: 1 q( t) [( s sb) il + ( sb s) il + ( s s) ilb s il s il 3 Q power broder mening thn the usul retie power. In ft, Unlike the retie power, whih onsiders only the fundmentl frequeny, the imginry power tkes into ount ll the hrmoni omponents of urrent nd oltge is why it is gien different nme (imginry power) s unit with the olt-mpere imginry (VAI). The prt of the reltions (5) nd (6), we n estblish the following mtrix: p S q s s S n the generl se, eh of the powers p nd q hs ontinuous prt nd prt lterntie, whih llows us to write the following expression P q P q + + ~ P q~ (6) (7) (8) 96

4 with: P Continuous power relted to the fundmentl omponent of tie power nd oltge, q Continuous power relted to the fundmentl omponent of retie urrent nd tension, ~ p nd q~ Powers of lternties relted to the sum of the omponents of disruptie urrent nd oltge. By inerting the reltion (7), we n relulte the urrents in the oordinte s shown in Eqution We obtin the following blok digrm for STF x s 1 + s s s s s p q (9) x Considering equtions (8) nd (9), we n seprte the urrent benhmrk in the three omponents, tie nd retie t the fundmentl frequeny nd hrmonis. Finlly, it is esy to obtin the referene urrents long the xes b by the inerse trnsformtion of Conordi 1 + ~ P q ~ (10) Fig 3. Self Tuning Filter Fig 5. Self Tuning Filter tuned t the pulstion ω The flow hrt of the ontrol lgorithm in the DSP softwre is shown in Fig. 4. i i b (11) Strt Initiliztion of proessor Initiliztion of ribles The self tuning filter is the most importnt prt of this ontrol whih llows to mke insensible the PLL to the disturbnes nd filtering orretly the urrents in - xis.hong-sok Song [6] hd presented in his PhD work how reoered the equilent trnsfer funtion of the integrtion expressed by The blok digrm of the STF tuned t the pulstion ω is shown in the figure 5. The trnsfer funtion of this filter is: Input dt from A/D ( S, Sb, i L, i Lb, V d) Filtrtion of i with STF DC oltge regultor with SMC ontrol iˆ ( s) ( s + K ) + jω H ( s) K i ( s) ( s + K ) + ω (1) Clultion of urrent referenes(i, i) Simplify.in.Clrke Trns.(i, i nd i ) Aording to the - xes, the expressions linking the omponents FMV output to input x omponents re: Digitl outputs DSP signls (i i b i ) K ( [ x s K ( [ x s ( s ) ( s ) ω ( s )] s ω ( s )] s ( s )) ( s )) (13) Fig. 4. The flow hrt of the ontrol lgorithm in the DSP softwre 97

5 B- Further referene urrents The finlity of the FAP is ommnd to ontrol the output urrents of the APF in order to nerest they follow their referenes. The priniple of this lwsuit is bsed on the omprison between the urrent generted by the FAP nd the referene urrent in order to dedue the ontrol orders power swithes. Hysteresis-bnd instntneous urrent ontrol PWM tehnique is populrly used beuse of its simpliity of implementtion, fst urrent ontrol response nd inherent pek urrent limiting pbility. This type of nonliner ontrol uses the error signl between the referene urrent nd the urrent produed by the APF see Fig. 6. The error is ompred to templte lled hysteresis bnd. One the error rehes the upper or lower bnd, new ontrol ommnd is sent to the semiondutor so s to mintin the tul urrent within the strip. The only prmeter interening in regulting is the width of the hysteresis bnd. It determines, on the one hnd the erge swithing frequeny nd on the other the error on the urrents generted. The hysteresis urrent ontrol is simple to implement nd gies good results in regultion nd gies good results in regultion beuse neither stti error nor following error. The ontrol is robust with respet to system prmeters nd exhibits good dynmi trnsient. -- -b- I f + - Swithing pulses Hysteresis -- I f Fig.4 - Hysteresis bnd urrent ontroller IV. Simultion results nd disussions Some simultion results using model in Mtlb-Simulink nd SimPower System Blokset re presented. The hrmoni urrent nd retie power ompensted by APF implemented in three- phse power systems with the utility power supply oltge of 100V nd urrent soure three- phse diode-bridge retifier with R-L lods s the urrent ompenstion objet. The design speifitions nd the iruit prmeters used in the simultion re prmeters re used for simultion: VS 50 V (rms), RS 0.1 Ω, LS mh, RC 0.01 Ω, LC 1 mh, Rd1 6.5 Ω nd Rd 17 Ω, Ld 1 mh, Vdr 140 V, C 1100 μf, HB (hysteresis bnd) 0.1 To study the performne of the APF, first simultion is done on fixed lod (RL1 & LL) nd the filter is swithed on t 0.1s. -d- Fig 5 Three phse min urrent (b) lod urrent; () Mins urrent; (d) ompensting urrent weform Fig 6. Power ftor orretion fter pplying PI ontroller. 98

6 We see tht before the onnetion of the APF, the mins urrent hs sme weform of the lod urrent. At 0.1s, the APF is onneted. mins urrent will be sinusoidl nd extly in phse with soure oltge. Iref(A) t(s) - - -b- Fig 7 -Mins urrent weform nd its spetrum, () before filtering, (b) fter filtering. Still in Fig.7 -b; spetrum nlysis shows tht IS urrent whih ontined hrmonis nd THDi 4.67%, will he one speter t fundmentl frequeny, ll hrmonis dispper nd the THDi.3%. To obsere the regulting proess in PI ontrol method in trnsient ondition nd the dynmis of the proposed APF, the DC side resistne is hnged from Rd1 to Rd t 0.s. It is ler from simultion results in Fig.8 tht we obtin good trnsient performne of the soure urrent, DC side pitor oltge for the PI ontroller nd the mins urrent mintins its sinusoidl weform. -d- Fig 8.Lod perturbtion response of PI ontrolled shunt APF. () lod urrent; (b) Mins urrent; () ompensting urrent weform (d) d oltge V. EXPERIMENTAL RESULTS The test benh used for the experiment ws deeloped in LGEB lbortory. The input step-down trnsformer (10.60KVA) is onneted to the mins (380 V line to line) nd deliers lumped oltge of 0 V. The three-phse prllel tie filter is hieed with oltge soure inerter. This VSI ontins three-phse IGBT 100V, 50A (SKM 50 GB 13D). To ensure the ded time of ontrol signls nd the insultion, deeloped rds bsed on the IXDP630 omponent nd speilized iruits (SKHI ) re used. -- -b- 99

7 Fig. 9. Experimentl APF results: lod urrent i L (A), filter urrent i F (A) nd soure urrent i S (A). Ch1 to Ch4 sle: 5 A/di. Time sle: 0 ms/di. We see tht before the onnetion of the APF, mins urrent hs sme weform of the lod urrent. At 0.14s, the APF is onneted. So, mins urrent will be sinusoidl Fig.11. Experimentl APF results : soure urrent i S nd its spetrum before filtering h5 Fig. 10. Experimentl APF results: lod urrent i L (A), filter urrent i F (A), soure urrent i S (A) nd soure oltge Vs (V). Ch1 nd Ch3 sle: 5 A/di; Ch sle: 100 V/di;Ch4 sle: 80 V/di; Time sle: 10 ms/di. Fig1.Experimentl APF results : soure urrent i S nd its spetrum fter filtering Figure 8 shows experimentl results for the mins urrent hs sinusoidl form nd in phse with supply oltge, whih minimizes the retie power onsumed by the lod. the DC bus oltge ontroller. The oltge Vd on the DC side of the inerter is stble nd regulted round its referene. In Fig. 9 spetrum nlysis shows tht i S urrent whih ontined hrmonis nd THD 6.4 % Howeer, fter filtering, this urrent he one speter t fundmentl frequeny, ll hrmonis dispper nd the THD 3.56%.( see Fig. 10). Finlly, to onfirm the effetieness of the proposed ontrol, double hnge of the referene is shown nd 40V. It n be noted tht fter rpid trnsient response, the DC oltge follows its referene; there is no oershoot nd the settling time is ery smll (see Fig. 1). Fig. 13 shows the orresponding results from the experimenttion 100

8 [5] Wenjin Di, Bofu Wng, Youhui Xie A Noel Fuzzy Logi Controller fro Atie power Filter CIMSA 009 Interntionl Conferene omputtionl intelligene for mesurement systems nd Applitions. [6] K. Hsn, nd K. Osmn, Globlly Stble Control of Three-Phse Three Wire Shunt Atie Power Filters, Ele. Eng., ol. 89, no.5, 007, pp [7] Helder J. Azeedo, José M. Ferreir, António P. Mrtins, nd Adrino S. Crlho Diret urrent ontrol of n tie power filter for hrmoni elimintion, power ftor orretion nd lod unblning ompenstion, Proeedings of the 10th Europen Conferene on Power Eletronis nd Applitions, EPE 03,Toulouse, 003, pp [6] D. Csdi, U. Reggini, nd G. Grndi, Atie power filters bsed on single urrent mesurement system, System Proeedings Symposium on Power Eletronis, Eletril Dries Adned Mhines Power Qulity (SPEEDAM 98), Itly, June 3-5, [7] K. H. Yiuw, nd M. S. Khnnihe, A noel three-phse tie power filter, Re. Energ. Ren,: Power Engineering, 001, pp [8] S.Beulieu, M. Ouhrouhe rel-time modelling nd simultion of n tie power filter ASTED Interntionl Conferene on Power nd Energy Systems PES 007, Clerwter, Florid, U.S.A. Fig.13. Experimentl APF results: DC oltge V d (V) nd DC referene oltge V d (V).Ch1 nd Ch sle: 100 V/di. Time sle: 1s/di [9] M. Abduslm, P. Poure nd S. Sdte, Study nd experimentl lidtion of hrmoni isoltion bsed on Self-Tuning-Filtetie filter, ISIE, IEEE Interntionl Symposium on Industril Eletronis, for three-phse Cmbridge, UK, (008). VII. Conlusion Experimentl results nd simultions show tht the shunt tie filter presents good dynmi nd stedy-stte response. It n perform hrmoni urrents ompenstion, together with power ftor orretion. It n lso In this work, we he shown the effetieness of the shunt tie power filtering espeilly with the pplition of PI ontrol nd with the pplition of the instntneous power bsed ompenstor.the THD of the soure urrent nd soure oltge fter ompenstion is well below 5%, the hrmonis limit imposed by the IEEE-519 stndrd. Further studies will exmine the opportunity of implementing high frequeny output filter with the three- phse inerter nd the power ftor ws orreted (power supply oltge nd urrent beme in phse). REFERENCES [1] S.Beulieu, M. Ouhrouhe rel-time modelling nd simultion of n tie power filter lasted Interntionl Conferene on Power nd Energy Systems PES 007, Clerwter, Florid, U.S.A. [] Mohmed Abduslm, Philippe Poure nd Shhrokh Sdte Control of Hybrid Atie Filter Without Phse Loked Loop in the Feedbk nd Feedforwrd Loops ISIE, IEEE Interntionl Symposium on Industril Eletronis, Cmbridge, UK, (008). [3] Mohmed Abduslm, Philippe Poure nd Shhrokh Sdte Control of Hybrid Atie Filter Without Phse Loked Loop in the Feedbk et Feedforwrd Loops [4] Abdelmdjid Choui, Jen-Pul Gubert Fteh Krim, Lurent Rmbult IP Controlled Three-Phse Shunt Atie Power Filter for Power Improement Qulity /06/ 006 IEEE. 101