Three Phase Active Conditioner for Harmonics Mitigation

Transcription

1 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 1 Three Phase Actve Condtoner for Harmoncs Mtgaton P.M. Balasubramanam and G. Gurusamy Abstract--- The Shunt Actve Power Flter s a very essental tool to remove harmonc currents and to remburse reactve power for nonlnear loads. The fundamental standard of process of a Shunt Actve Power Flter s to ntroduce an approprate non-snusodal current (compensatng current) nto the system at the pont of common couplng. Ths research work focuses on the tme-doman approach for three-phase Shunt Actve Power Flters through an effectve algorthm. A fundamental outlne and evaluaton of the performance of exstng mproved algorthms for actve power flters are presented. An enhanced approach based on tme doman technque s proposed based on varous complcated power qualty problems and varous compensaton functons. t s observed that the proposed algorthm provdes has shorter response tme delay when compared wth the conventonal approaches. Therefore, the proposed approach can accurately attan varous compensatng current references. ndex Terms--- Shunt Actve Power Flter, Synchronous Reference Frame, nstantaneous Reactve Power Theory, Pont of Common Couplng non-lnear power equpment s spreadng, the power qualty n the utlty networks s greatly affected and t becomes a major ssue. Thus, mnmzng the voltage dstorton has become an essental factor for both utltes and consumers. Fgure 1 llustrates the block dagram of the dstorton problem due to harmonc at low and medum power levels. Here, the utlty s denoted by a perfect ac voltage source n seres wth lumped mpedance representng lnes and transformers. The voltage waveform at the pont of common couplng s deformed due to harmonc current produced by the non-lnear load. Ths results n the followng effects on the power system components Falure of harmonc senstve loads ncreased losses n parallel connected capactor, transformers and motors napproprate functonng of protecton relays and crcut breakers [7] E. TRODUCTO LECTRC power generated by the apparatus s dstrbuted to the consumer n the form of 50 Hz ac voltage. The apparatus have a fxed control on the desgn and functon of the apparatus used for transmsson and dstrbuton, and can thus keep frequency and voltage delvered to ther consumers wthn close lmts. However, ncreasng segments of loads connected to the power system conssts of power electronc converters [1,]. These loads are nonlnear and ntroduce dstorted currents n the network whch n turn produce harmonc voltage waveforms. Wth the prolferaton of nonlnear loads such as dode/thyrstor rectfers, non-snusodal currents degrade power qualty n power Transmsson/dstrbuton systems []. otably, voltage harmoncs n power systems are becomng a serous problem for both utltes and customers. The deformaton whch may be due to a large sngle source or by the collectve consequence of numerous small loads, often propagates for mles along dstrbuton feeders [4, 5, 6]. As the applcaton of P.M. Balasubramanam, Assstant Professor, Department of EEE, KKT, Combatore. G. Gurusamy, Dean, Department of Electrcal and Electroncs Engneerng, Bannar Amman nsttute of Technology, Combatore. DO: /BJPSC.1515 Fgure 1: Harmonc Dstorton at PCC 1.1 Dstortons n Power ET Works The dfferent sources of dstorton n power networks convenently can be parttoned nto three classes based on the power level of the equpment and frequency range as Sub-cycle dstorton gve rse to flcker and occur usually at the hghest power level, they are caused by dynamc loads, such as arc furnaces, mll drves and mne wnders. Hgh frequency dstorton s caused by modern power electronc apparatus, due to hgh rate of rse of current and voltage. ntra- cycle dstorton, whch covers a very wde range of power, and results from the power processng SS Bonfrng

2 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 technque. The dstorton produced by these sources s generally termed harmoncs. 1. Power n Dstorted Ac etworks The actve and reactve power consttuents for electrc crcuts wth snusodal and lnear loads are well recognzed. The applcaton of the reactve and the harmonc power s an actual requrement for achevng reactve power compensaton and/or harmonc flterng n the scenaro of non-lnear loads. The component of the electrc power s assumng a snusodal voltage supply and a non-lnear load. n ths scenaro, the power factor s the product of the dstorton factor by dsplacement factor [8]. Power Factor = Dstorton factor x Dsplacement Factor The dsplacement factor corresponds to the power factor of systems wthout harmoncs. Ths factor may be called basc power factor, as t s based only on the current fundamental component. Alternatvely, the power factor, may be called total power factor, as t s based on fundamental and all harmonc components. Alternatvely, Sasak and Machda [1] theorzed that harmoncs could be removed through prncple of magnetc flux compensaton. Ths n prncple s the applcaton of current to generate a flux to counteract the flux formed by the harmoncs. Once agan, theoretcally, any number of harmoncs could be removed drectly. The current that would be needed to remove waveform deformaton caused by harmoncs was computed; however, a practcal control crcut was not realzed. Recently, ncredble development n capacty and swtchng performance of devces such as Bpolar Juncton Transstors (BJT), Gate Turn-Off thyrstors (GTO) and nsulated Gate Bpolar Transstors (GBT), has spurred n the nvestgaton of actve power flters for harmonc compensaton. Moreover, developments n topologes and control approaches for statc PWM converters have enabled actve power. Flter usng these converters to produce partcular harmonc currents, such as produced by non-lnear loads. Snce actve power flters are potental tools for the compensaton of current harmoncs generated through dstortng loads and also of reactve power, unbalance of nonlnear and fluctuatng loads. They can be lesser, more adaptable, better damped, more choosy, and less susceptble to falure for component drft than ts passve counterpart.. ACTVE FLTERG APPROACHES Fgure : Power Tetragonal Therefore, harmoncs cause Lower power factor. The power components n dstorted networks are denoted n power tetrahedron as shown n fgure.. ACTVE FLTERG TECHOLOGY The prmary effort to mnmze harmoncs wthout the utlzaton of tradtonal passve flters was made by B. Brd et al., [9]. Ths desgn depends on varyng the waveform of the current drawn by the load by nsertng a thrd harmonc current, dsplaced n phase, nto the converter tself. But, t s not possble to fully elmnate more than one harmonc wth ths approach [10]. Ametan [] presented another approach whch s based on expandng the current njecton technque to elmnate multple harmoncs. Based on ths approach, an actve control crcut could be utlzed to accurately fgure out the njected current. Ths current would comprse of harmonc segments of opposng phase, thus the harmoncs would be neutralzed, and only the basc component would reman [1]. Besdes, the potental concept, Ametan was faled n creatng a practcal crcut competent of generatng a precse current. The entre harmonc dstorton was mnmzed, but sngle harmoncs were not completely removed..1 Shunt Actve Flters The shunt actve flter technque s based on the prncple of njecton of harmonc currents nto the ac system, of the same ampltude but opposte n phase to that of the load harmonc currents. Fgure shows the actve power flter compensaton prncple, whch s managed n a closed loop approach to actvely fgure out the source current nto snusod.. Seres Actve Flters n seres actve flter confguraton, a voltage source, s generated n such a way that when ts voltage s added to the load voltage, the dstorted voltage s removed, therefore resultng n a snusodal voltage at the Pont of Common Couplng (PCC). For harmonc compensaton, both shunt and seres actve flters have lesser ratngs than the obvous power of the load. The shunt actve flter s rated for supply voltage, but a reduced current. n the case of seres dynamc flters, the rated load current passes va the flter but the rated voltage s agan lower. Hence, harmonc mnmzaton can be mplemented wth converters havng a mnmzed power ratng.. Hybrd Actve Flters Hybrd structures were ntroduced for harmonc compensaton of enormous rated loads n hgh voltage networks. Hybrd actve flters confguratons, ntegrates passve and actve flters. These flters enhance the SS Bonfrng

3 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 compensaton features of the passve flters and hence realze a mnmzaton n the ratng of the actve flter. They are specfcally approprate n nstallatons where L-C tuned passve flters already exst. n the hybrd seres confguraton, the seres voltage njecton s to be consdered as an solator, ether attanng the harmonc currents to be suppled to the non-lnear load or the harmonc currents that wll be absorbed by the tuned LCflters., seres and shunt. n the ntal scenaro, the njected voltage s n seres, and n the second scenaro t s n seres wth the shunt passve flter. V. COTROL METHODOLOGY Compensaton of harmones can be acheved n tmedoman or frequency doman. The frst approach depends on on lne calculaton of an nstantaneous error functon, at the same tme the second approach explots the prncple of Fourer analyss and perodcty of the ndstnct waveform to be corrected. n tme-doman, the error-functon could be calculated n the followng manner: 1. Extracton of the elementary consttuent from the dstorted waveform by usng a notch flter.. nstantaneous reactve power compensaton, whch explots an nstantaneous orthogonal power transformaton on mutually the actual and the fundamental consttuents of voltage and current to generate a power functon. The varaton between these two transformatons s the error.. Synchronous reference frame technque. Several PWM approaches exst (for compensaton n the tmedoman) to produce the gatng sgnals to the swtches and by ths means to rebuld the dstorted current. The shunt APFs are exploted most extensvely for stoppng the current dstorton. The performance of SAPF completely based on the characterstcs of the enhanced approaches and controllers. On the other hand, typcally one approach s only more sutable to some crcumstances but not to all crcumstances. An mproved algorthm of SAPF for harmonc elmnaton, power factor correcton, and balancng of nonlnear loads s proposed n ths paper. Fgure : SAPF System 4.1 Smulnk Model of the Overall System The smulaton of power electronc systems offers more benefts n the desgn process by permttng several alternatves. n order to confrm the practcablty of the proposed approach, a vrtual mplementaton of the SAPF s made usng Smulnk. The major elements are the reference compensaton current detector, a phase loop lock, a current controller, and a DC voltage controller. The reference compensaton currents are concluded and are provded as nput to a current controller to generate sgnals of the PWM nverter. Addtonally, snce the capactor voltage at the nverter termnal must be preserved at a stable level, the loss generated by swtchng and capactor voltage devaton s provded by the source. Smulatons reveal that the compensaton current calculator yelds mnor tme delay n steady state for the SAPF operaton 4. Mathematcal Modelng of the Proposed Method n the three-phase three-wre arrangement, the nstantaneous load currents of phase a, b, c ( a, b, and c ) can be dsassembled nto postve-sequence and negatvesequence consttuents based on the symmetrcal wegh law, whch was developed by Fortes cue ndependently. nk l nk l ( n) Sn π π Sn π π = x 1k 1k k k k = 1 Where, 0 x = a l = 1 x = b x = c ormally, only the postve-sequence, negatve-sequence, actve power and reactve power of the elementary current are concerned, and t s not essental to decompose the harmonc. Subsequently, the essental current component s gven as follows l l ( n ) = Sn π n π Sn n π π x1 = Sn n Cos Cos n Sn Sn n Cos () Cos n Sn The ntal term of () represents the postve-sequence component n phase wth the phase voltage, whch s the actve power consttuent of the postve- sequence elementary current; the second term of () represents the postvesequence element orthogonal wth the lne voltage, whch s the reactve power consttuent of the postve-sequence elementary current; the thrd term of () represents the negatve-sequence element n phase wth the lne voltage, whch s the actve power component of the negatve-sequence elementary current; the forth term of () represents the negatve-sequence component orthogonal wth the lne (1) SS Bonfrng

4 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 4 voltage, whch s the reactve power element of the negatve sequence elementary current. Fg. 4 llustrates the block dagram of the proposed current-detecton approach, n whch Sn π n s synchronous wth the postve-sequence elementary voltage of phase a, whch decdes the calculaton precson of actve and reactve power consttuents. The low-pass flter whch s utlzed decdes the performance of the complete system. n accordance wth dfferent compensaton purposes, the segregator wll acqure dfferent elements approprately, whch s advanced to the algorthm dependng on the nstantaneous reactve power theory. V. GA SELECTO n accordance wth the above confguraton, the control dffculty trms down to select the accurate gans for the model of Fg. 4.4 for a varety of operatng condtons. Consderng the samplng delay, the plant s an uncomplcated lag along wth an ntegratng component 1 U () H = plant 1 st s s Where T represents the samplng tme. The open-loop transfer functon H 0l wth the controller then becomes 1 st 1 pll U H = o1 K pll st 1 s s pll T s (4) Where K pll, T pll ndcates the gans related wth the P regulator. Ths s a typcal control setback very comparable to a current controlled speed loop of a drve system n whch the ntegral term n the plant mtates the mechancal nerta and the lag element emulates the current control loop. umerous technques can be exploted to choose the gans dependng on the preferred performance condton. n ths paper, the technque of symmetrcal optmum was exploted to compute the regulator gans. Based on ths technque, the regulator gans K pll and T pll are chosen such that the ampltude and the phase plot of H 01 are symmetrcal regardng the crossover frequency ω c, whch s at the geometrc mean of the two corner frequences of H 0l. A normalzng factor α s specfed, the frequency ω c, K pll, T pll are connected as followng equaton, ( ) ω = 1 ( α ) c T s (5) T = pll α T s K = ( 1 α )( 1 ( U pll T )) s Replacng (4) nto (5) t can be revealed that the factor α and the dampng factor ξ are connected by the assocaton α 1 ξ = By alterng α, the system bandwdth and dampng can be managed. A three-phase PLL system was formulated whch s approprate for tme doman nvestgaton under ndstnct utlty condtons and t was tuned the control effects, for nstance, loss of gan, lne harmoncs and frequency dsturbances. The PLL was entrely executed n software wthout the utlzaton of any hardware flters. When the reference u de s fxed to zero, the θ computed s synchronous wth the postve-sequence consttuent of elementary voltage. When u de s not fxed to zero, a constant phase dfference s between the θ and the postve-sequence consttuent of elementary voltage, whch make the control of the dsplacement feature easy. n addton, ths phase dfference wll not nfluence the strength of the chosen harmoncs detecton. The resultant smulaton dagram of the SPLL s shown n Fg.5. The phase voltage s determned by per-unt; the base quanttes for per-unt value are the maxmum value of postve-sequence elementary phase voltage. Subsequently, three phase voltages can be determned as, Sn n correspondngly. The nstantaneous power of the elementary current can be acqured by multplyng current by phase voltage as follows - ( n ) x 1 Sn n 1 4π 4lπ = 1 Cos Cos n 4π 4lπ Sn Sn n 4π 4lπ Cos 1 Cos n The ntal term of the equaton represents the nstantaneous actve power element of the postve-sequence elementary (the sum of three phases s steady, whch adds to the overall power delvered from source to load). The second term of the equaton represents the nstantaneous reactve power element of the postve-sequence elementary (the total of three phases s zero, whch travels between the phases and can be balanced by a compensator wthout an energy storage component). The thrd term represents the nstantaneous actve power element of the negatve-sequence elementary (the three-phase total of the prevous porton of ths tem s zero, whch travels between the phases and can also be balanced by a compensator wthout an energy-storage component). The three-phase sum of the remanng (together wth the posteror part of the thrd and fourth terms, whch s equal to Cos 4π n 4Π 4lπ Sn Sn n (6) and equvalent for each phase) s not zero, and ts frequency s two tmes the elementary, whch can be balanced by a compensator wth an energy-storage element). As a result, the negatve-sequence elementary currents do not add to the power delvered to the load. n the same way, the nstantaneous power of harmoncs can be obtaned by multplyng current as follows SS Bonfrng

5 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 5 ( n ) xk 1 nπ nπ = Cos ( k 1) Cos ( k 1) 1 k 1k 1k nπ nπ Cos ( k 1) Cos ( k 1) k k k t can be seen that ether the negatve-sequence or postve-sequence consttuent has one porton of whch the three-phase sum equal to zero, whch can be balanced by a compensator wthout energy storage, and the remanng can be balanced by a compensator wth energy storage. n (7) and (8), the least frequency consttuent s two tmes the elementary frequency; the dc consttuent can be obtaned by a low-pass flter wth a cutoff frequency lesser than double the elementary frequency or by a sldng-wndow wth / samples. Subsequently, multplyng by, the followng equaton can be obtaned: Multply (1) wth the followng equaton 4π 4lπ Sn n } Sn h (9) can be obtaned. Usng the smlar technque, the followng equatons can also be obtaned ( 4l ) = 1 Sn Sn π (10) Here, defne A A B B = Sn Sn Cos Cos (7) (8) () n () and represents the peak values of the A B reactve power consttuent and actve power consttuent of postve-sequence elementary current, correspondngly. A and are the maxmum values of the reactve power B consttuent and actve power consttuent of negatve-sequence elementary current of phase a, correspondngly. n accordance wth phase b and c, the maxmum values are ( ), ( ) and π Cos ( ) π Sn, ( π ) Cos Sn π respectvely, n the same way, multplyng Snk n and Cosk π lπ n, correspondngly, and gong through the low-pass flter, Axk and Bxk can be obtaned: ( k 1) lπ ( k 1) lπ (1) A = Sn xk 1k 1k Sn k ( k 1) lπ ( k 1) l = Cos π 1k k Cos k Sn n Bxk 1 ( 4 ) B = x 1 Cos Cos lπ Cos n ( n) C os n = x l π π Sn Sn n, (1) SS Bonfrng Subsequently, defne = A Cos (14) x n Sn n B n = A Cos x B xk = x1 = Sn n n A Cos x1 Bx 1 n A Cos x1 Bxk Snk n Sn n (15) (16) (17) Equatons () (16) generate the segregator shown n Fg. 4, by whch numerous results can be accomplshed based on dfferent compensaton purpose. When the SAPF s exploted to balance harmoncs and the negatve-sequence consttuent of the elementary current, the postve-sequence consttuent of the elementary current can be obtaned from (14), and the x current reference can be acqured as n) = ( n) ( n) by ( cx x x subtractng from the load current. When the lne current x after balancng s antcpated to be a symmetrcal three-phase elementary current, and the power factor s 1, the actve power consttuent of the postve-sequence elementary current px can be acqured by consderng A = 0 n (4.14), and the current reference can be acqured as ( n) = ( n) ( n) by cx x px subtractng from the load current. n the same way, by px fxng to zero, the reactve power consttuent of the B postve-sequence elementary current can be acqured. The negatve-sequence consttuent of the elementary current can be acqured by (15). When the APF s employed to balance the chosen order harmoncs, the compensatng reference can be acqured by (17). n fact, the actve power consttuent and reactve power consttuent of harmoncs do not requre to be segmented, as a result the factors and and Snk n Cos Cosk π n can be substtuted wth nkπ Sn nkπ separately. Subsequently, the programmng can be sgnfcantly smplfed. n accordance wth the detecton technques, several compensaton ams can be accomplshed by usng specfc combnatons. V. SMULK MODEL OF THE MPROVED ALGORTHM The major elements of the current detecton approach comprse a Soft Phase Loop Lock, a sne wave generator and the separator. The current detecton approach s employed based on the proposed approach to decde the reference balancng current. Fg. 4.6 and 4.7 llustrates the Smulnk model of the current detecton approach and the Soft Phase Loop Lock correspondngly. t s clear from the above nvestgaton that the delay resultant from the proposed approach s almost less than half

6 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 6 of the man cycle, whch s half of that of DFT and the equvalent as that of the approach depends on RPT. n addton, the algorthm proposed Fgure 6 llustrates the source voltage, load current and the source current after compensaton. Smulaton results of compensaton current produced by the controller are revealed n Fgure. 7. Fgure 4: Smulaton Dagram of the Proposed mproved Algorthm Fgure 6: Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase A Fgure 5: Smulaton Dagram of the Phase Locked Loop Possbly wll sense the postve/negatve-sequence elementary current, actve/reactve power consttuent of postve-sequence elementary current and selectve harmoncs approprately, whch s more flexble than the algorthm dependng on RPT and DFT. V. SMULATO CODTOS The major ntenton of the smulaton s to reveal the effectveness of the proposed SAPF control approach. Two test cases are consdered wth varety of source voltages and load condtons. n case 1, the source voltages are snusodal and balanced wth a magntude of 0 V and a frequency of ω=100π and the source supples an mbalanced nonlnear load. n case, mbalanced / dstorted source voltages provde an mbalanced nonlnear load n parallel wth an mbalanced load. 7.1 Smulaton Results for Snusodal, Balanced Source Voltages The balanced and snusodal three phase voltages taken nto consderaton are, V a =0 sn (ωt) V b =0 sn (ωt-10 o ) V c =50 sn (ωt10 o ) The load exploted s a brdge rectfer whch operates as a nonlnear mbalanced load.the smulaton results have been plotted ndvdually for a comprehensble nvestgaton. Fgure 6, Fgure 7, Fgure 8, llustrates the source voltage, lne current, reference compensaton current and source current after compensaton for the three phases correspondngly. Fgure 7: Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase B Fgure 8: Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase c SS Bonfrng

7 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 7 Fgure 9: Source Voltage, Load Current and Source Current after Compensaton Fgure 1: Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase B Fgure 10: Compensaton Currents Fgure 1: Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase C 7. Smulaton Results for Unbalanced / Dstorted Source Voltages n ths case, 0 V, 50Hz three phase voltage source s taken nto consderaton and rd order harmonc of 0. ampltude, phase angle zero s ntroduced n the postve sequence consttuent of phase A and a Fgure 14: Compensaton Currents Fgure : Source Voltage, Lne Current, Current Reference and Source Current after Compensaton for Phase A SS Bonfrng

8 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 8 Fgure 15: Source Voltage, Load Current and Source Current after Compensaton S.o Method for reference compensaton current calculaton % THD of source current for balanced supply voltage % THD of source current for unbalanced supply voltage 1 GRPT method SRF method SCD method Proposed method V. AALYSS OF SMULATO RESULTS The smulaton results are avalable for two cases consdered. t s clear that the SAPF njects harmonc currents nto the lne thereby makng the nput supply snusodal. The comparson of THD s gven n Table 1 for the three revewed and avalable methods namely Generalzed nstantaneous Reactve Power Theory based methods, Synchronous Reference Frame method and the Synchronous Current Detecton methods. From the results (Fgure. 16 and Fgure 17) t observed that for both balanced and unbalanced source voltages the THD for the proposed method s less than the avalable methods and also the delay resultng from the proposed algorthm s less than half of the man cycle, whch s half of that of DFT and the same as that of the algorthm based on RPT. Table 1: Comparson of % THD Fgure 16: THD Plot for Balanced Case Fgure 17: THD Plot for U Balanced Case Ffth order harmonc of magntude 0.15, phase angle 5 o s ntroduced n the negatve sequence consttuent of phase B for a tme perod of 0 to 1 seconds. Fgure, Fgure 1, Fgure 1 llustrate the source voltage, lne current, reference compensaton current and source current after balancng for the three phases correspondngly. Fgure 1 llustrates the source voltage, load current and the source current after compensaton. Smulaton results of compensaton current produced by the controller are llustrated n Fgure 14. X. COCLUSO Ths research work has formulated the mathematcal modelng and desgn of the reference compensaton current controllers for shunt actve power flters based on tme doman approach. The smulaton results of the proposed approach are compared wth that of the avalable results of Generalzed nstantaneous Reactve Power Theory based method, Synchronous Reference Frame method and the Synchronous Current Detecton methods. From the results t can be concluded that the delay resultng from the proposed algorthm s less than half of the man cycle, whch s half of that of DFT and the same as that of the algorthm based on RPT. From the analyss and smulaton t s found that the algorthm presented n ths thess has the advantages of flexblty, accuracy and easy mplementaton. Snce the reference compensaton currents are determned n the a-b-c reference frame, there s no reference frame transformaton s requred. Therefore, t results n less complexty n realzng the control crcut of SAPF and stll mantans good flter performance. After SAPF njects the compensaton currents, t s found that the source currents become deal and reman n phase wth the postve-sequence fundamental source voltages. Therefore, the utlty source power factor at the postve sequence fundamental frequency s acheved and the harmonc currents are well controlled. The Total Harmonc Dstorton (THD) study reveals that the proposed method has a source current THD less than the avalable methods. The proposed compensaton strategy of the SAPF s verfed through MATLAB/Smulnk whch yelds good agreement wth the expected SAPF goals. REFERECES [1] H. Akag, Y. Kanazawa, and A. abae, Generalzed theory of the nstantaneous reactve power n three-phase crcuts, n Proc. EEJ nt. Power Electron. Conf., Tokyo, Japan, 198, pp [] H. Akag and A. abae, nstantaneous reactve power compensators comprsng swtchng devces wthout energy storage components, EEE Trans. nd. Appl., vol. 0, no., pp , Mar./Apr [] A. Grgs, W. B. Chang, and E. B. Makram, A dgtal recursve measurement scheme for on-lne trackng of power system harmoncs, SS Bonfrng

9 Bonfrng nternatonal Journal of Power Systems and ntegrated Crcuts, Vol., o., September 01 9 EEE Trans. Power Del., vol., pp. 5 60, Jul H. Akag, ew trends n actve flters for power condtonng, EEE Trans. nd. Appl., vol., no., pp. 11 1, May/Jun [4] G.Chen,Y. Chen and K.M. Smedley, Three-phase four-leg actve power qualty condtoner wthout references calculaton, n Procd. EEE APEC '04, vol.1, pp , 004. [5] Vadrajacharya Kumar, P. Agarwal and H.O.Gupta, A Smple Control Strategy For Unfed Power Qualty Condtoner Usng Current Source nverter, n Procd. PEC007, pp [6] K. Vswanathan, D. Srnvasan, and R. Orugant, Desgn and analyss of SSO fuzzy logc controller for power electronc converters, n Proc. EEE nt. Conf. Fuzzy Syst., 004, vol., Jul. 5 9, 004, pp [7] P.M. Balasubramanam and G. Gurusamy, Evaluaton and mplementaton of Three Phase Shunt Actve Power Flter for Power Qualty mprovement, nternatonal Journal of Electrcal Engneerng, SS Volume 5, umber 7, pp , 01. [8] Kévork Haddad, Desgn and mplementaton of Three-Phase Four-Wre Actve Flters, [9] B.M. Brd, J.F. Marsch, P.R. McLellaa, "Harmone Reducton n Multplex Converters by Trple-Frequency Current njecton," Proc. EEE, 6((10). pp , Oct [10] E. Chandra Sekaran and P. Anbalagan, Comparson of eural etwork and Fast Fourer Transform Based Selectve Harmonc Extracton and Total Harmonc Reducton for Power Electronc Converters, Asan Power Electroncs Journal, Vol., o. 1, Apr 008. [] Ametan, "Harmonc R n Thyrstor Converters by Harmonc Current njecton." ars. Power App. Syst., PAS-95(), pp , Mar.lApr [1] S. L. Clark, P. Famour, and W. L. Cooley, Elmnaton of Supply Harmoncs: An Evoluton of Current Compensaton and Actve Flterng Methods, EEE, [1] H. Sasak, and T. Machda, "A ew Method to Elmnate Ac Harmonc Currents by Magnetc Flux Compensaton," EEE Tram on Power Apparatus andsysrerns, vol. PAS-90, pp , [14] Hongyu L, Fang Zhuo, Zhaoan Wang, Wanjun Le, and Longhu Wu, A ovel Tme-Doman Current-Detecton Algorthm for Shunt Actve Power Flters, EEE Transactons on Power Systems, Vol. 0, o., 005. [15] J. Moreland, Choosng a Smulaton Tool, EE Colloquum on Power Electronc Systems Smulaton (Ref. o. 1998/486), nterests are measurements, Bo medcal nstrumentaton, optmzaton and optmal control. P.M. Balasubramanam was born n Tamlnadu, nda, on May, he receved the B.E from Bharathyar Unversty, Taml nadu, nda.m.e from Anna Unversty, Taml nadu, nda. n 004, 006 respectvely, both n Electrcal engneerng. He s currently workng toward the Ph.D degree from department of Electrcal and Electroncs Engneerng. Hs research nterests are actve power flter and power qualty mprovement, control systems. G. Gurusamy was born n Srvllputtur, Vrudhunagar, nda 16 th October He receved BE degree n Electrcal Engneerng n 1967, M.Sc (Engg) n Appled Electroncs n 197 and PhD n Control Systems n 198 all from PSG College of Technology, Combatore, nda. He joned PSG College of Technology as lecturer n He was promoted as Assstant Professor n 198 and promoted as Professor n 1994 and became Head of the Department n 001. He then joned Bannar Amman nsttute of Technology Sathyamangalam Erode nda n 00 and he s currently the Dean of Electrcal and Electroncs engneerng there. He s Fellow of Systems Socety of nda. He establshed EEE Student Branch at PSG College of Technology, Combatore n 1974 and became ts counselor and contnued for 1 years. He was unanmously elected as Hon secretary, nsttuton of Engneers (nda) Combatore Centre n 198 and organzed several nternatonal and atonal Conferences. He was selected as Outstandng EEE Student Counselor n He has publshed more than 40 papers n atonal and nternatonal Journals and presented more than 60 papers at varous conferences. He has guded 9 PhD research projects and currently gudng 10 PhD research projects. Hs teachng and research SS Bonfrng