Distributed Control for the Parallel DC Linked Modular Shunt Active Power Filters under Distorted Utility Voltage Condition

Transcription

1 Dtrbted Control for the Parallel DC Lnked Modlar Shnt Actve Power Flter nder Dtorted Utlty Voltage Condton Reearch Stdent: Adl Salman Spervor: Dr. Malabka Ba School of Electrcal and Electronc Engneerng Dbln Inttte of Technology, Ireland

2 Table of Content. Bac Analogy. Actve Power Flter Intro. Introdcton of Propoed Work 4. Propoed Topology 5. Propoed Control Strategy Man and Sb-controller 6. Smlaton Relt 7. Conclon

3 Bac Analogy Concept Utlty Power blk UPS Backp

4 Bac Analogy Concept UPS Backp Utlty Power UPS Backp UPS Backp 4

5 Actve Power Flter The man am of the APF to compenate for the harmonc and reactve power dynamcally. Fgre : Non deal-load crrent Fgre : Injected converter compenaton crrent Fgre : Grd crrent after actve power flterng

6 Introdcton Parallel-APF confgraton ed, ntead of hgh capacty ngle nt, to add flexblty and relablty drng operaton Indvdal b-controller are ed for each APF nt to determne dtrbted harmonc crrent and reactve component wth the PWM crct Whle all the Sb-Controller are governed by one Man Controller. The control complexty gnfcantly redced wth e of the propoed controller. The propoed ytem ha been verfed nder dtorted and nbalanced grd voltage. 6

7 . Topology of Propoed Parallel Modlar APF t = t + t t L h + q. INDIVIDUAL SUB-CONTROL UNITS. MAIN CONTROL UNIT t t t L t + h + q t = = n n c t = t * n Fg. The power crct of the common dc-lnked modlar APF and aocated control nt 7

8 . Propoed Control Strategy A- Man Controller Fg. Man Controller 8

9 Therefore, the performance of the control method dependent on the type of PLL algorthm ed. In order to mprove the effcency of the PLL, the three-phae pply voltage a, b, c are tranformed ng the Clarke or α-β tranformaton nto a dfferent coordnate ytem by ng:. Propoed Control Strategy A- Man Controller 9 = c b a 0 0 β α

10 [ ] K a β α α ω = [ ] K α β β β ω + =. Propoed Control Strategy A- Man Controller 0 Fgre 4: Prncple Scheme of The STF

11 . Propoed Control Strategy A- Man Controller Fg. PI Reglator for Inverter Loe Mearement

12 . Propoed Control Strategy B Sb Controller Fgre 9: The propoed b-control ytem nt for each Inverter

13 Bede th, the n-balanced load crrent are alo mportant power qalty e that may redce the performance of the APF. For th reaon, the obtaned d and q component of the load crrent are alo proceed wth STF n order to calclate balanced crrent component. + a d co co co π π. Propoed Control Strategy B Sb Controller + = c b o q n n n π π [ ] K q d d d ω = [ ] K d q q q ω + =

14 . Propoed Control Strategy B Sb Controller After obtanng the balanced and ndtorted crrent component, the fndamental and harmonc component of ntantaneo crrent can be obtaned by ng eqaton, ~ d ~ q = = d q q d In the mot of the control method, a low-pa or hgh-pa flter ed to eparate the fndamental and harmonc crrent. However, there no need for an addtonal flter n the propoed control method 4

15 Fnally, the obtaned crrent harmonc component are then tranformed to the three phae converter reference crrent ng the nvere ynchrono tranform a gven by, = d ca ~ ~ n co n co * * π π. Propoed Control Strategy B Sb Controller = q cc cb ~ n co n co * π π

16 .Smlaton Relt The propoed control method mlated ng MATLAB/Smlnk and power ytem block et envronment to verfy the performance of the ytem. Three varable RL type non-ln ear load ed to ee dynamc performance of the modlar APF. Addtonally, a load ed to create adaddtonal nbalance crrent condton n the tded ytem. The ed parameter n thee work are gven n Table I. 6 TABLE I Parameter of the Analyed Sytem

17 .Smlaton Relt 7

18 Smlaton Relt.Operaton wth Sngle Inverter + 8

19 Smlaton Relt.Operaton wth Dal Inverter 9

20 Smlaton Relt.Operaton wth Trple Inverter 0

21 Conclon In th paper, we have condered the degn of a modlar actve power flter APF n order to dtrbte the total compenaton crrent for nbalanced nonlnear load. Th acheved wth a flexble and n-blky olton that mantan low power lo for the reqred level of harmonc ppreon and reactve power compenaton. The controller complexty of the modlar APF gnfcantly redced wth the e of the propoed control trategy. The propoed ytem compre a man controller and a nmber of b-controller. The former ed to determne the reqred common gnal for each b-controller, wherea the b-controller themelve e the common gnal to generate the reqred compenaton for each branch.

22 Conclon A beneft of havng a modlar APF ytem come from the fact that a falty b-nt can be olated from the ytem for repar whlt the ytem tll n operaton. Another beneft offered by a modlar ytem the ablty to modfy the nmber of parallel branche dependng on the power demand of the plant. A major advantage of havng the type of dtrbted controller cheme propoed n th paper the elmnaton of the need for repeated gnal proceng reqred for each nverter. The ytem nder tdy wa mplemented on RT-LAB real-tme expermental platform to evalate the real-tme performance of the ytem. The THD of the grd crrent wth e of propoed method are redced to ~ % nder both grd voltage and freqency flctaton condton, whch meet the IEEE recommended tandard.

23 Acknowledgment: Dr. Samet Brck Eropean Unverty of Lefke, North Cypr Pot-Doc from Dbln Inttte of Technology DIT, Dbln, Ireland & Dr. Malabka Ba Dbln Inttte of Technology DIT, Dbln, Ireland

24 IECON'04 The 40th Annal Conference of the IEEE Indtral Electronc Socety Sheraton Hotel Dalla - Dalla, TX - USA October 9 - November, 04 4

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