A Recent Approach to Repetitive Control Strategy for Induced Draft Fan

Transcription

1 Europan Journal of Applid Scincs 9 (5): , 217 ISSN IDOSI Publications, 217 DOI: /idosi.jas A Rcnt Approach to Rptitiv Control Stratgy for Inducd Draft Fan G. Thanigaivl, M. Vijayakarthick, S. Sathishbabu and P.K. Bhaba 1 Dpartmnt of Elctronics and Instrumntation Enginring, Annamalai Univrsity, Annamalai Nagar, India 2 Dpartmnt of Chmical Enginring, Annamalai Univrsity, Annamalai Nagar, India Abstract: In this work, dsign and dvlopmnt of controlling inducd Draft fan in a ta industry is proposd. Th aim of this work is to control th Inducd Draft Fan in a diffrnt priodic input signals. An ida of Nw Modifid Rptitiv Control Stratgy (NMRCS) of ID fan is introducd. Basd on th nonlinaritis prsnt in th systm and th input rfrnc signal is priodic in natur, th convntional typ controllrs givs poor satisfactory tim-varying trajctory spd control. To xamin th proposd tchniqu, simulation runs ar carrid out and prformanc masurs ar invstigatd in trms of tracking rror and th rsults confirm th dominanc of NMRCS controllr. A robustnss of th proposd control stratgy is also tstd. Ky words: ID fan NMRCS Rptitiv control Rational factor INTRODUCTION basd on th principl of fdback, whr output rrors ar fd, through a controllr, back to th input. Th cost Inducd Draft Fan is on of th rotating quipmnt of this fdback is th possibility of causing instability, in a ta industry. It maintains th tmpratur in th whr boundd inputs to th systm ar abl to produc drying unit as pr procss rquirmnt. Th flu gass unboundd outputs, vn for a priori stabl systms. gnratd in th air hating stov to b suckd by This convntional controllr usually lavs larg transint Inducd Draft fan and to maintain rquird tmpratur rrors whn th systm is subjctd to priodic insid dryr. disturbancs. Errors may b du to intractions, dlays Th ta industris gnrat wast in th diffrnt and othr lmnts of dynamics that prvnt rigid tuning. forms lik Grn laf wast, Dust, Nois, Frmnting To ovrcom this problm, Rptitiv controllrs basd aroma, solid wast in this most of as is not crating any on th Intrnal Modl Principl (IMP) ar placd in th problms to nvironmnt. But co2 on of th major control loop. Th main contributions of th work constitunt of th GHG mission through chimny taks prsntd in this papr ar prcisly implmntation of considrabl attntion in thir nvironmntal pollution, th Nw Modifid Rptitiv Control Stratgy in an ID bcaus most of th industris using coal, Firwood fan and analyzs th tracking prformanc. In sction 2 and lignit for th thrmal nrgy sourcs. Th furnacs th mathmatical modl of ID fan is summarizd. Th in th ta industris ar installd with vry long back and dsign and structur of Nw Modifid Rptitiv Control it oprating with vry low fficincy that claims th highr Stratgy is dtaild in sction 3. Simulation rsults ar amount of flu gass with vry high tmpratur that mix analyzd in sction 4 to xmplify th bttr prformanc with th atmosphr, this incras th atmosphric air of th NMRCS in closd loop. Finally, sction 5 concluds tmpratur and also incrasing th co2 lvl in th th papr. surrounding aras. Thrfor, control of tmpratur is prdominant in Idntification of Modl Paramtrs and Controllr th ta industry. In gnral, controllr [1] may also ffort Sttings to rduc th magnitud of actuator signals, th tim Mathmatical Modl Dscription: Th fan modl is takn takn for th output to rach its dsird valu or th ffct from th simulation softwar HVACSIM+. Th inducd of disturbancs. Usually th convntional control is draft fan modl is xprssd as follows [2]. Corrsponding Author: M. Vijayakarthick, Dpartmnt of Elctronics and Instrumntation Enginring, Annamalai Univrsity, Annamalai Nagar, India. 258

2 C f ω 3 = ρ ND 1Pf Ch = ρ 2 2 N D h= + 1 f + 2 f + 3 f + 4 f C a ac a C a C a C f = + 1 f + 2 f + 3 f + 4 f n C C C C (1) (2) (3) (4) Th RCS includs th factor which has pols at jk, k =, ± 1,.., ± (corrsponding to th harmonic and sub harmonics of th basic priod L), th controllr can track any priodic signal and rjct any disturbanc of priod L. Basd on this concpt, RCS is constructd with a modl of. Th basic Rptitiv control structur shown in Fig. 1. E f ωpf = ρ n f PD Controllr Dsign: Th PD controllr paramtrs (Kc and Kd) ar dsignd by using a optimization tool in MATLAB platform [3] and modl paramtrs ar automatically optimizd to gt th dsird prformanc rquirmnts as givn in Tabl 1. Th optimizd PD controllr sttings ar K c= and K d= Tabl 1: Prformanc spcification for PD control systm Ris tim (tr) 2 Sttling tim (ts) 22.2 Ovr shoot (Mp) 2% Rptitiv Control Stratgy (RCS): Rptitiv control stratgy [4]-[6] is considrd for tracking a priodic input signal and liminating a priodic load signal. Th Rptitiv Control Stratgy (RCS) dsign is basd on th Intrnal Modl Principl (IMP) and it is proposd by Wonham and Francis [7]. Th IMP stats that if any xognous signal can b rgardd as th output of an autonomous systm, th inclusion of th modl of th signal in a stabl closd-loop systm can promis idal tracking or complt limination of th priodic signal. (5) Implmntation of Nw Modifid Rptitiv Control Stratgy (NMRCS): Th modlling of ID fan motor is uncrtain for high frquncy signals. At high frquncis, nois signal will affct th rspons, which lads to instability of ID fan. To mt out this troubl, a low-pass filtr (Q(s)) is introducd to th xisting RCS loop and to mak sur th ID fan stability. This structur is namd as Modifid Rptitiv Control Stratgy (MRCS) [8]. To nhanc th stability of MRCS basd on snsitivity, a Nw Modifid Rptitiv Control Stratgy [9] is proposd and givn in Fig. 2. Fig. 2: Nw Modifid Rptitiv Control Stratgy Th snsitivity function of th proposd schm is givn by 1 s( jw ) = = d PC PCV jwtd jwtd (6) Fig. 1: Rptitiv Control Stratgy Th snsitivity function dscribd by quation (6) is plottd as shown in Fig. 3. In th magnitud rspons, th snsitivity at th priod frquncis is smallr than th MRCS configuration. This mans that th rrors with frquncis btwn th priod frquncis ar minimizd with th NMRCS than th MRCS. 259

3 Magnitud (db) Phas (dg) Proposd NMRCS Original RCS Fig. 3: Magnitud of th snsitivity function Frquncy (Hz) 1 Bod Diagram Magnitud (db) Phas (dg) Frquncy (rad/sc) Fig. 4: Frquncy rspons of ID fan Dsign Procdur and Guidlins RESULTS AND DISCUSSIONS Dsign of Low Pass Filtr: A first ordr continuous tim low pass filtr is considrd hr. Th cut-off In th simulation tst, th input rfrnc priodic frquncy of low pass filtr is obtaind from th Bod plot sinusoidal signal with known priod (L = 62) and of th ID fan motor systm as shown in Fig. 4. It is found amplitud (V pp = 5) is gnratd and applid to ID fan with to b.33. NMRCS basd PD mod. Th tracking rspons is rcordd in Fig. 5. In addition to that an simulation runs Dsign of Rational Factor: By utilizing a simpl of MRCS basd PD mod and convntional PD optimization tchniqu th rational factor (V) is obtaind mod control loop ar carrid out and rsponss ar by considring minimum tracking rror as an objctiv tracd in Fig. 6 and Fig. 7.In all th cass th nominal function. Th idntifid valu of V for ID fan is.2. oprating point of % of spd is maintaind. 26

4 From th rsponss, th tracking rrors ar obtaind robustnss of th NMRCS, a simulation runs of th ID with rspct to tim and rsults ar chartd in Fig. 8 fan for a priodic trapzoidal signal with known priods and Tabl 2. It is obsrvd that NMRCS in control and amplitud valus (L=,Vpp= 5) is carrid out. loop is capabl of tracking dynamic priodic rfrnc Figurs (9 to 12) justify th robustnss of incorporation of trajctoris with minimum rror. To inspct th NMRCS in control loop Fig. 5: NMRCS: Simulation tracking rspons of sinusoidal priodic rfrnc trajctoris [Priod (L) = 62, Fig. 6: MRCS: Simulation tracking rspons of sinusoidal priodic rfrnc trajctoris [Priod (L) = 62, Fig. 7: PD: Simulation tracking rspons of sinusoidal priodic rfrnc trajctoris [Priod (L) = 62, 261

5 18 Absolut tracking rror NMRC MRC PI Itration Fig. 8: Simulation absolut tracking rror rsponss of sinusoidal priodic rfrnc trajctoris [Priod (L) = 62, Fig. 9: NMRCS: Simulation tracking rspons of trapzoidal priodic rfrnc trajctoris [Priod (L) =, Fig. 1: MRCS: Simulation tracking rspons of trapzoidal priodic rfrnc trajctoris [Priod (L) =, 262

6 Fig. 11: PD: Simulation tracking rspons of trapzoidal priodic rfrnc trajctoris [Priod (L) =, Absolut tracking rror NMRC MRC PI Itration Fig. 12: Simulation absolut tracking rror rsponss of trapzoidal priodic rfrnc trajctoris [Priod (L) =, Tabl 2: Prformanc analysis of diffrnt control stratgis Sinusoidal Trapzoidal Control stratgis L: 62 & Amp A: 5 L: 45 & A: 5 NMRC ATE: 63 ATE: 159 MRC ATE: 7 ATE: 188 PD ATE: 16 ATE: 2 CONCLUSION In this work, a nw modifid rptitiv control stratgy is proposd and valuatd using simulation for ID fan. An input of priodic rfrnc signal to proposd controllr is xcutd and prformanc analysis is don in trms of absolut tracking rror. A comparativ study with convntional PD is also carrid out. Th rsults clarly show th domination of th proposd NMCS in ID fan. Robustnss of th NMRCS is also invstigatd. Nomnclatur: Cf: Dimnsionlss air flow rat [-] Ch: Dimnsionlss prssur had [-] D: Diamtr of fan whl [m] Ef: Fan powr consumption [kw] f: frquncy of invrtr [Hz] N: Fan rotation spd [r/s] Pf: Fan prssur had [Pa] w: Fan supply air mass flow rat [kg/s] ñ: Air dnsity [kg/m3] a, a 1, a 2, a 3, a 4 Fittd cofficints using fan spcification data, 1, 2, 3, 4 Fittd cofficints of fan fficincy quation using fan spcification data 263

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