@ ACTIVE CURRENT SHAPING FOR BETTER UTILITY INTERFACE A dissertation submitted to the Department of Electrical Engineering, University of Moratuwa in partial fulfillment of the requirements for the degree of Master of Science by MATHARAGE HASATH CHANDIKA PERERA SRf lanka M O R A T U W A Supervised by: Dr. J. P. Karunadasa Department of Electrical Engineering University of Moratuwa, Sri Lanka January 2009 University of Moratuwa 9 2 9 7 0 9 2 9 7 0 6x\< z(p«f3 T W - D E C L A R A T I O N T h e w o r k s u b m i t t e d in th is d isser ta t ion is the resul t of m y o w n inves t iga t ion , e x c e p t w h e r e o t h e r w i s e s ta ted. It has not a l ready b e e n a c c e p t e d for any deg ree , a n d is a lso not be ing c o n c u r r e n t l y s u b m i t t e d for any o ther degree . M.H. C h a n d i k a Pere ra I e n d o r s e the dec la ra t i on by the cand ida te . Dr. J .P. K a r u n a d a s a C O N T E N T S Dedica t ion i Abs t rac t v A c k n o w l e d g e m e n t vii List of F igu res vii i List of T a b l e s ix C H A P T E R I I N T R O D U C T I O N 1.1. P o w e r s y s t e m h a r m o n i c s & e f fec ts of h a r m o n i c s 1 1 . 2 . M e a s u r e s of h a r m o n i c s 3 1 .3 . Impo r tance of h a r m o n i c mi t iga t ion 3 1 . 4 . M e t h o d s of h a r m o n i c mi t iga t ion 4 1 .5 .Ac t i ve P o w e r Fi l ters 6 1 .6 .Ob jec t i ves 8 1 .7 .Thes is O r g a n i z a t i o n 8 C H A P T E R 2 M A T E R I A L S A N D M E T H O D S 2 .1 .Acqu is i t i on of vo l t age and cur ren t s igna ls of the p o w e r a p p l i a n c e 2 . 1 . 1 . S a m p l e load 9 2 .1 .2 .Da ta acqu is i t i on card '. 10 2 . 1 . 3 . H a r d w a r e c i rcui t 11 2.1.4. Acqu is i t i on of vo l t age and cur ren t s igna ls by M A T L A B 12 2 . 1 . 5 . M A T L A B Data acquisition tool box 13 2 .2 .Ana l ys i s of acqu i red s igna ls us ing M A T L A B 15 2.3. D e t e r m i n a t i o n of the approp r ia te f i l ter cur ren t 18 2 .4 .S imu la t i on to i m p l e m e n t act ive p o w e r f i l ter 2 .4 .1 .C i rcu i t a r r a n g e m e n t of the s imu la t i on 19 2 .4 .2 .S imu la t i on to ob ta in c i rcui t p a r a m e t e r s 21 2.5. Va l i da t i on of the acqu i red c i rcui t p a r a m e t e r s 23 C H A P T E R 3 R E S U L T S 3.1. E lect r ica l p a r a m e t e r s of the load 3.1.1. V o l t a g e s igna l o f the s a m p l e load 24 3 .1 .2 .Cu r ren t s igna l of the s a m p l e load 25 3.1.3. E lect r ica l p a r a m e t e r s of the s a m p l e load 26 3 .2 R e q u i r e d cu r ren t f r om the f i l ter 3 .2 .1 .Cur ren t of the capac i to r cha rge r 26 3.2.2. Fi l ter cu r ren t w i th capac i to r cha rge r 27 3.3. S imu la t i on resul ts 3 .3 .1 .Se lec t ion of the inductor 28 3 .3 .2 .Se lec t i on of the s tep up t r ans fo rmer 31 3 .3 .3Se lec t i on of the sw i t ch ing f r equency 33 3 .4 Va l i da t i on 3.4.1 .Va l ida t ion for load var ia t ions 36 3 .4 .2Va l ida t ion for supp ly vo l tage var ia t ions 39 i i i C H A P T E R 4 D I S C U S S I O N R e f e r e n c e s 4 7 A n n e x - 1 A n n e x - 2 A n n e x - 3 4 8 4 9 50 A B S T R A C T I nc reased use of non l i nea r e lec t r ica l l oads in jects h a r m o n i c cu r ren t s to p o w e r sys tems. H igh leve ls of powe r s y s t e m h a r m o n i c s c rea te vo l t age d i s to r t i on a n d en la rge p o w e r qua l i ty p rob lems . H a r m o n i c s resul t in poor p o w e r fac tor , l owe r e f f ic iency a n d in te r fe rence to ad jacen t c o m m u n i c a t i o n s y s t e m s . T h e h a r m o n i c cur rents f l ow into the uti l i ty supp l y l ines p r o d u c e s ex t ra losses. A n ac t ive p o w e r f i l ter uses a sw i t ch ing inver ter to p r o d u c e h a r m o n i c c o m p e n s a t i n g cu r ren ts . The m a j o r ob jec t i ve of th is p ro jec t w a s to e l im ina te e f fec ts of h a r m o n i c s a n d to improve p o w e r fac to r of a typ ica l non l i nea r load. A t t e m p t s w e r e m a d e to app l y ac t i ve power f i l ters for cu r ren t s h a p i n g of a spec i f i c load, con t ra ry to its c o m m o n app l i ca t ions of app ly ing at the po in t o f c o m m o n coup l ing . The Na t iona l I ns t rumen ts U S B - 6 0 0 8 mu l t i func t ion da ta acqu is i t i on ( D A Q ) m o d u l e w a s used to acqu i re da ta f r om the s a m p l e load viz. the c o m p u t e r p o w e r supp ly . A potent ia l d i v ide r w a s i nco rpo ra ted to the c i rcui t to acqu i re v o l t a ge s igna l . C u r r e n t s ignal w a s a c q u i r e d us ing a ser ies resistor . Filter cu r ren t w a s i m p l e m e n t e d by sw i t ch ing an induc to r us ing fou r i nsu la ted ga te bipolar t rans is to rs ( IGBT) a r r a n g e d in H b r idge con f igura t ion . T h e s imu la t i on c i rcu i t was i m p l e m e n t e d us ing M A T L A B S imu l i nk so f twa re tool . I n d u c t a n c e of the s w i t c h i n g inductor , vo l t a g e of the s tep up t r ans fo rmer and the sw i t ch ing f r e q u e n c y of t he sys tem w e r e ob ta i ned by s imu la t ion . S u b s e q u e n t l y the a b o v e c i rcu i t p a r a m e t e r s we re va l i da ted for va r iab le loads us ing total h a r m o n i c d is to r t ion as the d i s c e r n i n g cr i ter ion. V It w a s poss ib le to r educe T H D of the cu r ren t w a v e of c o m p u t e r p o w e r s u p p l y f r o m 1 0 7 % to 12%. P o w e r fac to r w a s i m p r o v e d f r om 0.66 to uni ty. By i n c r e a s i n g t he power fac to r to uni ty, the cur ren t f l ow can be r e d u c e d by a p p r o x i m a t e l y 3 4 % . T h e obse rva t i ons m a d e here in are app l i cab le for h a r m o n i c e l im ina t ion in n o n l i n e a r l oads in gene ra l w i th n e c e s s a r y mod i f i ca t ions . vi A C K N O W L E D G E M E N T I a m grea t l y i ndeb t to m y supe rv i so r Dr. J. P. K a r u n a d a s a , H e a d of D e p a r t m e n t , D e p a r t m e n t of E lect r ica l Eng ineer ing , Un ivers i ty of M o r a t u w a , M o r a t u w a fo r his eve r p resen t w o r d s of w i s d o m . D e p a r t m e n t of E lect r ica l Eng ineer ing , a n d the D e p a r t m e n t of M e c h a n i c a l e n g i n e e r i n g of the Un ivers i ty of M ra tuwa , M o r a t u w a fo r p rov id ing m e this i m m e n s e l y v a l u a b l e oppor tun i t y to car ry ou t a p o s t g r a d u a t e p ro jec t w i t h all t he faci l i t ies a n d g u i d a n c e in a p leasan t env i r onmen t . I w i s h to reco rd m y gra t i tude to the labora to ry s ta f f t he D e p a r t m e n t of E lec t r ica l Eng ineer ing , Un ivers i ty of M o r a t u w a , M o r a t u w a for the t echn i ca l s u p p o r t in ca r r y ing out m y r e s e a r c h wo rk . Fur ther to the s ta f f of the R e g i o n a l s u p p o r t C e n t e r ( S o u t h e r n / U v a ) of Nat iona l W a t e r supp ly and D r a i n a g e Board , M a t a r a fo r the i r suppor t . Final ly, I s h o u l d t h a n k m a n y ind iv idua ls , f r iends and co l l eagues w h o h a v e no t b e e n m e n t i o n e d he re pe rsona l l y in m a k i n g th is educa t iona l p rocess a s u c c e s s . M a y be I cou ld not h a v e m a d e it w i thou t you r suppor ts . v i i LIST OF F I G U R E S Figure 1.1: F igure 1.2: F igure 2 .1 : F igure 2.2: F igure 2.3: F igure 2.4: F igure 2.5: F igure 2.6: F igure 3.1: F igure 3.2: F igure 3.3: F igure 3.4 F igure 3.5: F igure 3.5: F igure 3.6: F igure 3.7: F igure 3.8: F igure 3.9: F igure 3 .10: F igure 3.11: F igure 3 .12 Typ i ca l a r r a n g e m e n t of a pass i ve f i l ter C o m p e n s a t i o n charac te r is t i cs of a para l le l ac t ive p o w e r f i l ter H a r d w a r e c i rcui t to ob ta in vo l t age and cur ren t s igna ls S c h e m a t i c rep resen ta t i on of the da ta acqu is i t ion us ing M A T L A B M A T L A B c o m m a n d s used for da ta acqu is i t i on M A T L A B c o m m a n d s used for w a v e f o r m ana lys i s C i rcu i t d i a g r a m of the para l le l ac t ive fi l ter S imu la t i on c i rcui t V o u l t a g e s igna l of the s a m p l e load Cu r ren t s igna l of the s a m p l e load C u r r e n t w a v e of the capac i to r cha rge r C u r r e n t w a v e f o r m requ i red f r o m the para l le l ac t i ve f i l ter W a v e f o r m ob ta ined for i n d u c t a n c e of 1 0 m H , s tep up v o l t a g e of 3 5 0 V a n d sw i t ch ing f r e q u e n c y of 1 0 0 k H z W a v e f o r m ob ta ined for i nduc tance of 1 0 m H , s tep up vo l t age of 3 5 0 V and sw i t ch ing f r equency of 1 0 0 k H z W a v e f o r m ob ta ined for i nduc tance of 5 0 m H , s tep up v o l t a g e of 3 0 0 V and sw i t ch ing f r equency of 5 0 k H z W a v e f o r m ob ta ined for i nduc tance of 5 0 m H , s tep up v o l t a g e of 3 5 0 V and sw i t ch ing f r equency of 1 0 k H z Resu l tan t tota l cu r ren t o b s e r v e d under i n d u c t a n c e of 5 0 m H , s tep up vo l t age of 3 5 0 V and sw i t ch ing f r equency of 1 0 0 k H z Resu l t an t to ta l cu r ren t o b s e r v e d unde r 5 0 % load u n d e r s e l e c t e d c i rcu i t p a r a m e t e r s Resu l t an t to ta l cu r ren t o b s e r v e d unde r 1 6 0 % load u n d e r s e l e c t e d c i rcui t p a r a m e t e r s Resu l t an t to ta l cu r ren t o b s e r v e d unde r 9 0 % of supp ly vo l t age u n d e r se lec ted c i rcui t p a r a m e t e r s Resu l tan t total cu r ren t o b s e r v e d unde r 1 1 0 % of supp l y v o l t a g e u n d e r se lec ted c i rcui t p a r a m e t e r s V I I I L I S T O F T A B L E S T a b l e 2 . 1 : T h e i n p u t r a n g e a n d t h e r e l e v a n t l e ve l o f a c c u r a c y T a b l e 3 .1 : E l e c t r i c a l p a r a m e t e r s o f t h e s a m p l e l o a d T a b l e 3 .2 : T o t a l h a r m o n i c d i s t o r t i o n v a r i a t i o n w i t h t h e i n d u c t a n c e T a b l e 3 .3 : T o t a l h a r m o n i c d i s t o r t i o n v a r i a t i o n w i t h t h e s t e p u p t r a n s f o r m e r v o l t a g e T a b l e 3 .4 : T o t a l h a r m o n i c d i s t o r t i o n v a r i a t i o n w i t h s w i t c h i n g f r e q u e n c y T a b l e 3 .5 : T o t a l H a r m o n i c D i s t o r t i o n v a r i a t i o n f o r d i f f e r e n t l o a d v a r i a t i o n ix