Simulation and Analysis of Single Phase Shunt Active Filter Based on PQ Theory

Transcription

1 215 IJEDR Volume 3, Issue 4 ISSN: Smulaton and Analyss of Sngle Phase Shunt Ate Flter Based on PQ Theory 1 Anoop H. Budhran, 2 Krshna Veer Sngh, 3 Amt R Pathak 1 Assstant Professor, 2 Assstant Professor, 3 Assstant Professor 1 Eletral Engneerng Department, 1 V. V. P. Engneerng College, Rajkot, Inda Abstrat Ths paper deals wth the analyss and smulaton of sngle phase shunt ate flter based on PQ theory. Normally PQ theory s used for 3 phases 3 wres and 3 phases 4 wre system but here t s used for sngle phase system as well. Ths paper also onentrates on reduton of THD of load urrent [1]. Sne the system has only sngle phase sgnal for both oltage and urrent, thus the dummy sgnal wth a phase shft of 12 º dfferent angels must be generated for prodng the nput for pq theory. Durng smulaton the sx pulses wll be generated for swthng of IGBT but only two wll be used. MATLAB tool s used to smulate the proposed sheme. Index Terms Shunt ate flter, THD (Total harmon dstorton), PQ theory. I. INTRODUCTION The Power Eletron onerters and loads are the soures of harmons and reate power whh greatly affet the performane of the power system network[1].to oerome the problem of power qualty, reent efforts hae been made on deelopment of better flterng tehnque. The ate flters gathered more onentraton beause of exellent performane to oerome the harmon and reate power problems. But the performane of the ate flters depends upon shunt ate power flter wth ontrollng done oer Instantaneous ate and reate power (PQ) theory has been purposed to erfy ts apablty and ablty to redue the harmons [3]. The adantage of pq theory s that t s nstantaneous and t performs n tme doman system. The shunt ate flter onneted to AC dstrbuton system n the presene of dfferent shares of Eletron loads [1] s analyzed. It has been nestgated through smulatons that een under unbalaned and dstorted states of dstrbuton supply oltage and unbalaned loadng, shunt ate flter s able to mtgate the harmons (THD) spefed by power qualty standards the ontrol theory that s employed to formulate the ontrol strategy of the ate flter [2]. Due to exesse use of power onerters and other nonlnear loads n ndustry t s obsered that the power systems oltage and urrent waeforms gets deterorates. Stat power onerters suh as sngle phase and three phase retfers, Thyrstor onerters and maxmum number of power eletron dee are nonlnear loads whh produe onsderable large dsturbanes n the supply and dstrbuton system. Mostly oltage harmons and power dstrbuton ssues are arse due to urrent harmons generated by nonlnear load [5]. when nonlnear urrents flow n the eletral system and the dstrbutontransmsson lnes, supplementary oltage dstorton produe due to the mpedane present n the eletral network. Due to the presene of harmons n the power system arous power losses ours n dstrbuton, nterferene problem n ommunaton system and, sometmes result n operaton falure of eletron dee whh are more senste beause t ontans ontroller systems, whh an work wth low energy leels [6]. It has been obsered that nonsnusodal urrent results n many problems for the utlty power supply ompany, suh as low energy effeny, eletromagnet nterferene (EMI) and dstorton of lne oltage et. II. PRINCIPLE OF SHUNT ACTIVE POWER FILTER The shunt ate power flter wth d bus whh use to get adjust tself has a topology smlar to that of a stat ompensator (STATCOM) whh s basally used for reate power ompensaton n transmsson systems. Shunt ate power flters ompensate harmons by nsertng equal but opposte ompensatng urrent nto the system. Durng ths proess the ate flter works as a urrent soure njetng the harmon omponents generated by the load but phase shfted by 18. Fg 2 shows the bas ompensaton prnple of a shunt ate power flter. The load urrent, the desred mans urrent and ompensatng urrent njeted by the ate flter are ontanng the all harmon omponents to make mans urrent snusodal. The shunt ate flter adds the ompensatng urrent n the load urrent to prode the snusodal urrent. IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 861

2 215 IJEDR Volume 3, Issue 4 ISSN: III. MATHEMATICAL MODEL Fg. 1: Prnple of sngle phase shunt ate power flter In ths method algebra transformaton whh s most popularly known as Clarke transforms [2] s used for three phase oltage and urrent. These three phase oltage and urrent are then onerted nto αβ oordnate. Aordng to ths theory three urrent and three oltage sgnals are used but t also an be used for sngle phase ate flter by makng the two dummy urrent and oltage sgnal wth 12º angel of shftng. Durng ths proedure separaton n mean and osllatng alues takes plae. Consder load urrent of sngle phase load as phase a and others phase (phase b and phase ) are generated by duplatng tehnque. The load urrent s assumed as phase a urrent and wth be expressed mathematally as shows n eq. (1). By assumng that eq. (1) as phase a load urrent, load urrent for phase b and an be represented as n eq. (2) and eq. (3). n 2I sn( w ) (1) a n b 2 sn( 12 ) I w (2) n 2 sn( 12 ) I w (3) Equaton (1), (2) and (3) an be transformed n matrx form as shown n (4) and (5) for load urrent and load oltage respetely: 1 a o b a o b The α and β referene urrent are obtaned usng algebra transformaton and shown wth the help of eq (6) for load urrent and n eq (7) for load oltage. a a (4) (5) a 3 3 b (6) IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 862

3 215 IJEDR Volume 3, Issue 4 ISSN: a 3 3 b The equaton for the ate and reate power an be obtaned as [1]: p (8) q (9) p q Ate power and reate power onsst of two part whh are aerage part and osllatng part also known as DC part and AC part. The equatons of ate power and reate power an be gen as: p p p (11) q q q (12) The DC part an be alulated by usng lowpass flter, whh use to extrat the hgh frequeny sgnal and prodes the fundamental omponent (DC part). From the DC part ate power and reate power. The αβ omponent of the urrent an be represented as n equaton (13). 1 The three phase referene urrent of ate power flter shown n eq (14) before the sgnal wll subtrated from load urrent. The subtrated three phases urrent wll be used to generate PWM sgnal usng hysteress band. Hysteress band wll produe sx PWM sgnals and for sngle phase ate flter only two are used as nput. * ab * (1) (13) (7) (14) IV. SINGLE PHASE SHUNT ACTIVE FILTER Fg 2 a system onfguraton of a snglephase or threephase shunt ate flter for harmonurrent flterng of a 1phase or 3 phase dode retfer wth a apate d load. The ate flter s one of the most bas system onfguratons among arous forms of pure and hybrd ate flters [4]. The d load may be taken as an a motor dren by a oltagesoure PWM nerter n many ases. Ths shunt ate flter s normally onneted wth the transformer s onneted n parallel wth the harmonprodung load. The ate flter an be ontrolled on the bass of the followng feed forward manner [5]. 1. The ontroller measures the nstantaneous load urrent. 2. It extrats the harmon urrent from the measured load urrent by means of dgtal sgnal proessng. 3 The ate power flters draw the ompensatng urrent from the supply so that t an anel out the harmon urrent [6]. IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 863

4 215 IJEDR Volume 3, Issue 4 ISSN: Fg. 2: Sngle phase shunt ate flter The blok dagram shown n fgure 3 shows the ontrol strategy based on pq theory whh s used to generate the PWM sgnal. V. ALGORITHM OF APPLIED CONTROL STRATEGY Fg. 3: Control strategy of pq theory From lterature surey t an be onlude that shunt ate flter s a useful dee for ompensaton of urrent harmons due to nonlnear loads. The THD due to nonlnear loads an be brought to lmts aordng to IEEE standards by usng shunt ate flter. IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 864

5 215 IJEDR Volume 3, Issue 4 ISSN: Start Load Current and Soure Voltage Measurement Clarke Transformaton,, & p & q Calulaton p p ~ p q q q~ HPF for p Calulaton and q Calulaton f reate power s to be ompensated Compensatng Current Calulaton & Inerse Clarke Transformaton a, b & End Fg. 4: Flowhart for the alulaton of ompensatng urrent VI. SIMULATION OF 1PHASE SHUNT ACTIVE FILTER BASED ON PQ THEORY [Ilne] [Iload] pow ergu Dsrete, Ts = 5e6 s. TNB Soure A [ab] B RECTIFIER In1 Load In2 In3 Out1 In4 Gatng Pulse Generaton Usng PQ Theory Cs INVERTER load urrent1 g A B Cs1 Shunt Ate Flter Fg. 5: Smulnk model of shunt ate flter The modelng of pq theory whh onssts of sngle to three phase blok, algebra transformaton[1] of pq theory three phase to two phase, two phase to three phase transformaton and hysteress band s shown n fgure 6. Hysteress band wll produe sx sgnals PWM and for sngle phase ate flter only use two sgnals to ontrol the sngle phase ate flter[8]. Fg. 6: Modelng of pq theory IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 865

6 215 IJEDR Volume 3, Issue 4 ISSN: VII. VARIOUS WAVEFORMS OF LOAD CURRENT & SHUNT ACTIVE FILTER Fg 7. (A) LOAD CURRENT Fg 7 (B) ACTIVE FILTERS CURRENT The effeted nonlnear load of the system wll make the THD of load urrent nrease up to % as shown n Fg. 8. By njetng the ate flter urrent the THD offlne urrent wll redue to.85% as shown n Fg 9 Fg 8 THD of load urrent Fg 9 THD of lne urrent IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 866

7 215 IJEDR Volume 3, Issue 4 ISSN: VIII CONCLUSION A program has been deeloped to smulate PQ theory n MATLAB tool. It s found from smulaton results that shunt ate power flter mproes power qualty of the power system by elmnatng harmons whh makes the load urrent snusodal and n phase wth the soure oltage. A model has been deeloped and smulated to erfy the results The PQ theory based shunt ate power flter has better performane to the other ontrollng methods and t s tme doman method as well. REFERENCES [1] H. Akag, "Trends n Ate Pow Lne Condtoners," IEEE Trans. On Power Eletrons, ol. 9, 1994, pp [2] B. Sngh, K. AlHaddad, and A. Chandra, "A Reew of Ate Flter for Power Qualty Improement," IEEE Trans. on Industral Eletrons ol. 46, 1999, pp [3] A. Bhattaharya, C. Chakraborty, and S. Bhattaharya, "Shunt Compensaton Reewng Tradtonal Methods of Referene Current Generaton," IEEE Industral Eletrons Magazne, MIE'9, ol. 3,29, pp [4] H. Akag, Y. Kanazawa, and A. Nabae, "Instantaneous Reate Power Compensators Comprsng Swthng Dees wthout Energy Storage Components Ler p," ol. I, 1984, pp [5] H. Akag, "New Trends n Ate Flters for Power Condtonng," IEEE Trans. on Industry Applatons, ol. 32, 1996, pp [6] H. Akag, E.H. Watanabe, and M. Aredes, Instantaneous Power Theory and Applatons to Power Condtonng, New Jersey: Jhon Wley & Sons, 27 [7] M.T. Haque, "Sngle Phase pq Theory," Power Eletrons Spealsts Conferene, PESC 2, pp , 22., 22, pp [8] M.T. Haque and T. Ise, "Implementaton of Sngle Phase pq Theory," Power Conerson Conferene, PCC'2, ol. 2, 22, pp [9] E.H. Watanabe, R.M. Stephan, and M. Aredes, "New Conepts of Instantaneous Ate and Reate Powers n Eletral Systems wth Gener Loads," IEEE Trans. on Power Delery, ol. 8, 1993, pp [1] M.K. Mshra and P.K. Lnash, "A Fast Transent Response Sngle Phase Ate Power Flter," IEEE Regon 1 Conferene, TENCON'5, 25, pp. 16. [11] A. Koohak, S. H.Fath, M.Dandar. Sngle phase applaton of spae etor pulse wdth modulaton for shunt ate power flters[c]. IEEE Internatonal symposum on Industral eletrons,27: [12] M. Satou and N. Matsu, "A Control Strategy of Sngle Phase Ate Flter Usng a Noel dq Transformaton," Industry Applaton Conferene, IAS'3, 23, pp IJEDR Internatonal Journal of Engneerng Deelopment and Researh ( 867