Control of the Shunt Active Power Filter under Non-ideal Grid Voltage and Unbalanced Load Conditions

Transcription

1 Dbln Inttte of Technology Conference paper School of Electrcal an Electronc Engneerng Control of the Shnt Actve Power Flter ner Non-eal Gr Voltage an Unbalance Loa Conton Samet Brck Dbln Inttte of Technology Soyan Ref Eropean Unverty of Lefke Cypr Ozgr Ozerem Near Eat Unverty - Cypr Malabka Ba Dbln Inttte of Technology, malabka.ba@t.e Follow th an atonal work at: Part of the Electrcal an Electronc Common Recommene Ctaton Brck, S.; Ref, S.; Ozerem, O.C.; Ba, M., "Control of the hnt Actve Power Flter ner non-eal gr voltage an nbalance loa conton," Power Engneerng Conference UPEC, 48th Internatonal Unverte', vol., no., pp.,5, -5 Sept. o:.9/upec Th Conference Paper broght to yo for free an open acce by the School of Electrcal an Electronc Engneerng at ARROW@DIT. It ha been accepte for nclon n Conference paper by an athorze amntrator of ARROW@DIT. For more nformaton, pleae contact yvonne.emon@t.e, arrow.amn@t.e, bran.w@t.e.

2 Control of the Shnt Actve Power Flter ner Non- Ieal Gr Voltage an Unbalance Loa Conton Samet Brck Dbln Inttte of Technology & Eropean Unverty of Lefke Soyan Ref Eropean Unverty of Lefke Ozgür Cemal Ozerem Near Eat Unverty Malabka Ba Dbln Inttte of Technology Abtract-In th ty a new metho propoe n orer to mprove the harmonc ppreon effcency of Actve Power Flter for the problem cae by the torte an nbalance voltage wth nbalance loa crrent n control trategy. The propoe control metho gve an aeate compenatng crrent reference even for non eal voltage an nbalance crrent conton. The relt of mlaton ty are preente to verfy the effectvene of the propoe control techne n th ty. Inex Term--Actve Power Flter, Park Tranformaton, Clark Tranformaton, Self Tnng Flter, Unbalance Loa Crrent an Voltage. I. INTRODUCTION Non-lnear electrcal evce have became common place n ntral an commercal faclte. Compter power pple rectfer epment, ometc applance, ajtable pee rve are ome example of thee non-lnear loa. Thee non-lnear power electronc loa raw non-noal crrent from ac man an cae a type of voltage an crrent torton calle harmonc []. Thee harmonc cae varo problem n power ytem an n conmer proct, ch a epment overheatng, blown capactor, tranformer overheatng, exceve netral crrent, low power factor, etc. In orer to olve thee problem, Actve Power Flter APF ha rawn mch attenton nce the 97, becae they have excellent compenaton charactertc. They are evelope to ppre the harmonc crrent an compenate for reactve power, mltaneoly. For th propoe, the power converter of an actve power flter controlle to generate a compenaton crrent that eal to the harmonc an reactve crrent. In orer to etermne the harmonc an reactve component of the loa crrent, everal techne are ntroce n the lteratre []. Thee tratege apple to APF play a very mportant role n the mprovement of the performance an tablty. The control trategy affect the cot, teay tate, an ynamc performance of the flter. The common pont of the nvetgate control techne the nee of gr voltage mearement []. The nbalance voltage ally occr becae of varaton an nbalance n the loa arng from fferng phae of the loa crrent e to fferent network mpeance for example. Therefore, the ynamc charactertc of the harmonc etecton metho wol lkely be averely affecte wthot proper coneraton of the voltage nbalance, torton an crrent nbalance. In th ty, we propoe a new metho to ncreae the harmonc ppreon effcency of three phae three wre APF n the cae of both non-eal gr voltage an nbalance loa crrent conton. II. ACTIVE POWER FILTER In th ty, we coner three-phae ytem wth varable nonlnear loa. The block agram of a bac threephae APF connecte to a general non-lnear loa hown n Fg.. Fg.. Block agram of the APF The man am of the APF to compenate for the harmonc an reactve power ynamcally. The APF overcome the rawback of pave flter by ng the wtchng moe power converter to perform the harmonc crrent elmnaton. The three-phae loa crrent ha a nonnty power factor. Therefore, the crrent rawn by the pobly reactve loa wth harmonc an gven by: t t t t L h where L t the loa crrent, t the fnamental crrent, h t the harmonc crrent an t the reactve crrent. A conventon, hnt APF are operate a a crrent orce n parallel wth the loa. The power converter of an APF controlle to generate a compenaton crrent, c t, whch eal to the harmonc an oppote phae,.e., //$. IEEE

3 t t t h c, Th yel a noal orce crrent gven by n t S. III. PROPOSED CONTROL METHOD In the propoe control metho, frt the loa crrent a, b, c are tranforme nto the component n the Synchrono Reference Frame coornate ytem by ng followng park tranformaton: c b a o n n n co co co π π π π, 4 where, the angle the anglar poton of the ynchrono reference. It a lnear fncton of the anglar poton of the gr voltage. Th anglar poton can be etermne by the a of a Phae-Locke-Loop PLL. Therefore, the performance of the control metho epenent on the type of PLL algorthm e. In orer to mprove the effcency of the PLL, the three-phae pply voltage a, b, c are tranforme ng the Clarke or - tranformaton nto a fferent coornate ytem by ng: c b a. 5 Then, we obtane two phae voltage procee by the elftnng flter STF. STF wa frt e n orer to etmate the phae angle of PWM converter otpt [4] an e n [5-9]. In [6], the tranfer fncton obtane from the ntegraton of the ynchrono reference. The tranfer fncton efne a: j U V H x, 6 where j t j t V t e e U t t. 7 The STF ha a magnte an phae repone that mlar to thoe of a general ban-pa flter. Apart from the ntegral effect on the npt magnte, the STF oe not alter the phae of the npt,.e. the npt U an otpt V have the ame phae. Note that n orer to have nt magnte,.e. H B, a contant X ncorporate n to E. 6, that, X X X j U V H. 8 In the tatonary reference, the fnamental component are gven by: [ ] a, 9 [ ]. Then, the obtane n-torte an balance two phae voltage can be convert to the three phae ytem by ng nvere Clark tranformaton a gven by, c b a. By th metho the anglar poton of the orce voltage can be etermne correctly by ng PLL. Bee th, the n-balance loa crrent are alo mportant power alty e that may rece the performance of the APF. For th reaon, the obtane an component by 4 are alo procee n the propoe control metho n orer to calclate balance crrent component. [ ], [ ]. After obtanng the balance an ntorte crrent component, the fnamental an harmonc component of ntantaneo crrent can be obtan by ng 4 an 5, repectvely, ~, 4 ~. 5 In the mot of the control metho, a low-pa or hgh-pa flter e to eparate the fnamental an harmonc

4 crrent. However, there no nee for an atonal flter n the propoe control metho. Fnally, the obtane crrent harmonc component, from 4 an 5, are then tranforme to the three phae converter reference crrent ng the nvere ynchrono tranform a gven by, * co n ca ~ * π π 6 cb co n ~ * cc π π co n A block agram repreentaton of the propoe control metho hown n Fg.. IV. SIMULATION RESULTS The propoe control metho mlate ng MATLAB/Smlnk an power ytem block et envronment to verfy the performance of the ytem. Three varable RL type non-lnear loa grop Loa, Loa & Loa are e to ee ynamc performance of the APF. Atonally, a lnear loa Loa 4 e to create atonal nbalance crrent conton n the te ytem. The e parameter n thee work are gven n Table I. TABLE I PARAMETERS OF THE ANALYZED SYSTEM Symbol Qantty Vale v S, f Lne to Netral Volt. & Fre. 4 V, 5 Hz Z Gr Impeance mω,.6 µh Z c Converter Impeance mω, mh Z L Loa Impeance mω,. mh Loa Non-Lnear Loa Re. an In. 6 Ω, mh Loa Non-Lnear Loa Re. an In. Ω, mh Loa Non-Lnear Loa Re. an In. 8 Ω, mh Loa 4 Lnear Loa Re. an In. 4 Ω C c APF c Capactor µf U c c- Lnk Voltage 75 V p & Proportonal & Integral Gan.88 & & STF Gan & 4 f Swtchng Freency 4 khz In th ty, the Total Harmonc Dtorton THD of the gr voltage n each phae are.8 %,.79 % an 8. %. The voltage between phae to netral n each phae are 4.4V, 6.V, 47.5V. The gr voltage waveform can be een n Fg.. Moreover, the THD of the loa crrent n each phae are.76 %,. % an 5. % whle the RMS crrent are 9. A, 5.4 A, 5.4 A. In the econ loa combnaton the crrent are ncreae to 49. A, 5.A, 4,96 A. The crrent waveform of the loa grop can be een n Fg. 4. Fg.. Three phae nbalance an torte non-eal gr voltage Fg.. The block cheme of the propoe control metho Fg. 4. Unbalance varyng loa crrent ner non-eal voltage conton.

5 After convertng the three phae voltage to two phae coornate ytem - a ecrbe n 5, the gr voltage are procee by ng STF a gven n 9 an. Then, the obtane ntorte an eal two phae voltage waveform are tranforme to three phae voltage waveform by ng nvere Clarke tranformaton ee E.. Relate waveform to thee proceng are gvng n Fg. 5. Moreover, the harmonc component are btracte from fnamental to obtan two phae converter reference crrent. For th, atonal low pa flter or hgh pa flter not e. Then, the obtane two phae reference crrent gnal are converte to three phae a gven n Fg. 7 by ng 6. Fg. 7. Three phae converter crrent Fnally, the gr crrent waveform obtane a gven n Fg. 8. The THD of the gr crrent are rece from % to aron %. Fg. 8. Gr crrent after flterng by propoe control metho ner torte an n-balance gr voltage wth nbalance loa conton V. CONCLUSION Fg. 5. Voltage waveform, a- Three phae nbalance an torte gr voltage, b- Gr voltage after tranformaton to - at the npt of STF, c- The obtane balance an ntorte two phae voltage waveform at the otpt of STF, - The obtane balance an ntorte three phae voltage waveform at the npt of PLL. After obtanng the correct anglar poton of the ynchrono reference, the an component are calclate by ng park tranformaton a gven n 4. Secon STF egne a ecrbe n an to proce an component. By th metho, balance an component are obtane. In orer to compenate converter loe the DC-lnk capactor voltage procee by ng conventonal PI reglator. The DC-lnk voltage waveform at the capactor termnal gven n Fg. 6. In th paper, we have conere to egn a control metho n orer to generate correct reference crrent gnal to atfy the rerement of harmonc ppreng an reactve power compenaton for the nbalance nonlnear loa combnaton ner cae of non-eal gr voltage conton. In the propoe metho, the torte an nbalance voltage frt procee by ng Self Tnng Flter to etermne the correct anglar poton. Then econ STF e to extract balance loa crrent waveform after obtanng the fnamental an harmonc component of ntantaneo crrent by ng park tranformaton. In th ty, atonal low-pa or hgh-pa flter not e to extract harmonc component from the fnamental. The mlaton te how that the propoe control techne gve an aeate compenatng crrent reference. ACNOWLEDGEMENTS The athor acknowlege the fnancal pport by the Eropean Unon ner contract no: / VI. REFERENCES [] W. M. Gray, S. Santoo, "Unertanng power ytem harmonc", IEEE Power Eng., Rev., pp. 8-. [] B. Sngh,. Al-Haa,, A. Chanra, "A revew of actve flter for power alty mprovement", IEEE Tranacton on Intral Electronc., vol. 46, no. 5, pp , 999. Fg. 6. DC-lnk termnal voltage wth the propoe control metho

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