TUNING MODEL REFERENCE ADAPTIVE CONTROLLER FOR AVR OF SYNCHRONOUS GENERATOR 1

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1 IJCCCE, OL.11. NO., 11 CONTROLLER FOR AR OF SYNCHRONOUS 1 Dr. Abulrahm Thab Humo Abstract A Tunng Moel Reference Aatve Controller (TMRAC) for a synchronous generator s resente n ths aer. The controller erforms the functon of termnal voltage of the machne. The roose controller s use to overcome the roblems of nonlneartes an arametrc uncertantes for Synchronous Generator (SG). The results verfy mrove erformance of TMRAC comare to conventonal Automatc oltage Regulator (AR) uner varous oeratng contons. Keywor: Moe Reference Aatve Controller, synchronous generator, Automatc oltage Regulator (AR) الخلاصة في ھذا البحث تم تقدیم مسیطر النموذج المرجعي التكیفي الم نغم (TMRAC) لمولد متزامن.. ی ؤد ي المسیطرة وظیفة تنظیم الفولطیة الطرفیة للماكنة. ی ست عمل جھازالسیطرة الم قت ر حللت غ ل ب على مشاكل ألاخطیة وعدم وثوقیة المتغیرات للمولد المتزامن. أثبتت الن تاي ج أداء م حس ن لمسیطر النموذج المرجعي التكیفي الم نغم بالمقارنة مع منظم الفولطیة الا لي الاعتیادي تحت ظروف الاشتغال الم خ ت ل فة. 1 Ths aer was resente n the Engneerng Conference of Control, Comuters an Mechatroncs On Jan. 3-31/11, Unversty of Technology. Electrcal an Electronc Engneerng Deartment/ Unversty of Technology. 56

2 IJCCCE, OL.11. NO., Introucton Synchronous generators are resonsble for the bulk of the electrcal ower generate n the worl toay. The voltage stablty an ower ualty of the electrcal system een on roer oeraton of AR. Synchronous generator exctaton control s one of the most mortant measures to enhance ower system stablty an to guarantee the ualty of electrcal ower t roves. The man control functon of the exctaton system s to regulate the generator termnal voltage whch s accomlshe by ajustng the fel voltage wth resect to the varaton of the termnal voltage [1]. Synchronous Generator n a ower system s non-lnear an fast actng whch s contnuously subjecte to loa varatons [,3]. Nowaays, Desgn technology of AR s beng broaly mrove. Nonlneartes an arametrc uncertantes are unavoable roblems face n controllng the outut voltage of SG when workng alone or wth others. Fg (1) shows a block agram of SG an AR system [4]. Conventonal lnear controllers for the synchronous generator consst of the AR to mantan constant termnal voltage an the turbne governor to mantan constant see an ower at some set ont. They are esgne to control, n some otmal fashon, the generator aroun one artcular oeratng ont; an at any other ont the generator s amng erformance s egrae [5]. A number of new control theores an methos have been ntrouce to esgn hgh erformance exctaton controllers to eal wth the roblem of transent stablty for nonlnear synchronous generator moels. Among them are the Lyaunov metho, sngular erturbaton methos, feeback lnearzaton an slng moe control, lnear otmal control, the aatve control metho assocate wth neuro technue, the fuzzy logc control theory [,6]. The roose controller n ths aer s TMRAC [7]. It s use to esgn an AR for a non-lnear an fast actng synchronous generator whch s subjecte to contnuously loa varatons. The controller arameters are tune accorng to ther effect on the rse tme, eak over shoot an steay state resonse where each arameter s examne searately an ajuste to overcome ther rft. The voltage stablty s obtane even though the lant mathematcal moel s unknown. Fg (1) Block agram of a synchronous generator an AR. Moel Reference Aatve Controller (MRAC) The MRAS s one of the man aroaches to aatve control. The esre erformance can be exresse n term of a reference moel. The system conssts of two loos; an nner loo, whch s an ornary feeback loo, comose of the lant an the regulator. The arameters of the regulator are ajuste by the outer loo n such a way that the error between the lant outut an the moel outut becomes small. The outer loo s thus also a regulator loo. The roblem s to etermne the ajustment mechansm whch brngs the error to zero for all comman sgnals. The block agram of the MRAC s shown n Fgure (). 57

3 ossble to obtan R an G from euaton (4), an must be have fast resonse comare Fgure () Block Dagram of MRAC [8] Fgure (3): Regulator Block Dagram A sngle-nut sngle-outut system, whch may be ether a contnuous tme or a screte tme moel, s gven by [8] B yt ut (1) A where eg A eg B Where u s the control sgnal an y s the outut sgnal. The symbols A an B enote olynomals n fferental oerator. The olynomal A assume to be monc (the frst coeffcent s unty). The regulator can be foun accorng to the relaton between comman sgnal u c an the esre outut sgnal y m as Bm ym t uc t Am A general lnear control law s R u T u G y 3 c where R, T an G are olynomals. Fgure (3) shows the regulator block agram. A P R B P G B A A m 4 where A m s the esre moel oles, A s the observer oles ( they are fast resonse than esre oles) an B s the cancelle zeros (t s use to cancel the effect of lant zeros). Observer oles are ae to become wth esre oles. The olynomal T can be foun from the followng euaton T A B 5 P P P m / b 1 Am A (6) where P s a stable monc olynomal of the same egree as R The flter error can be ntrouce as Q e f y y m 7 Fltere error n term of regresson vector can be wrtten as bq 1 e T f u 8 A Am P1 where Q s a olynomal whose egree s not greater than A Am egree, s the regresson vector an s the true regulator arameters. The feeback control law s T u P 1 9 where s the actual regulator arameter. Usng ths control law, t follows from e. (8) that that the Introuce the sgnals ς an µ, efne by 1 T u 1 P1 bq e f 11 A A m 58

4 where s the augmente error an ς s the error augmentaton. The Graent Rule that use for uatng arameters s 1 t where γ s the aataton gan. Fgure (4) shows a block agram of a moel reference aatve controller. The controller s esgne usng Matlab/Smulnk, the reference moel s a secon orer an the nut sgnal s a unt ste sgnal. The lant of synchronous generator moel wth saturaton non-lnearty s taken from Matlab toolbox. s reresente n the rotor reference frame ( frame). All rotor arameters an electrcal uanttes are vewe from the stator. They are entfe by rme varables. The subscrts use are efne as follows:,: an axs uantty R,s: Rotor an stator uantty l,m: Leakage an magnetzng nuctance f,k: Fel an amer wnng uantty The electrcal moel of the machne s R s R (13) t Where L L ( ) an m f k L L m k Rs R (14) t Fgure (4): the block agram of a MRAS for SISO system 3. The Synchronous Generator Moel (Plant) The synchronous generator termnal voltage uner faulte conton has been shown that the ynamc resonse of SG n a ractcal ower system when a fault occurs s very comlcate nclung many nonlneartes such as the magnetc saturaton. However, the classcal thr orer ynamc generator moel has been commonly use for esgnng the exctaton controller. Ths thr orer moel can be shown n [3]. The MATLAB/SIMULINK toolbox synchronous generator moel takes nto account the ynamcs of the stator, fel, an amer wnngs. The euvalent crcut of the moel f t R f f f (15) Where L L ( ) k f f f t m R k k k (16) Where L L ( ) k k k m R (17) t k 1 k 1 k 1 k 1 Where k 1 L k 1 k 1 L m R (18) t k k k k Where k L k k L m k f 59

5 The saturaton non lnearty can be ae to the synchronous generator moel by actvate the saturaton of fel current n MATLAB / SIMULINK rogram. 4. Determnaton of Controller Parameters For the lant has exact mathematcal moel the controller arameters can be obtane rectly by alyng euatons 4 an 5. But the controller arameters for Synchronous Generator whch has nonlneartes an arametrc uncertantes can not foun rectly from euatons 4 an 5. The arameters of regulator can be etermne as follows (1) Set all arameters of the regulator an aataton gan (γ) to zero. () Alyng test sgnal to the system (lant an the controller) an observe the resonse. (3) Set an arbtrary value for last coeffcent for olynomal T(s) of the regulator arameters then recor ts effect on the resonse, change ts value untl goo results obtane. (4) Reeat ste 3 for other coeffcents of olynomal T(s) conseuently untl the frst coeffcent. (5) Reeat ste 3 an 4 for olynomal R(s) an G(s) conseuently. 5. Smulaton an Results The AR for SG wth saturaton effect of excter s esgne an mlemente usng the conventonal PID an TMRAC whch are shown n fgures (5 an 6) resectvely, an the arameter for SG use n the smulaton are shown n table (1). The stuy of the regulator arameters T ( s) t s t s t, R( s) G( s) g s r s an g s g effect on the transent an steay state resonse of SG wth zero aataton gan can be one by alyng smulnk rogram shown n fgure(6). t : Increase the value of ths arameter wll ten to ecrease the rse tme an ncrease the steay state level as shown n fgure (7). Fgure (7) shows the resonses of fferent values of arameter t wth the resent of excter saturaton (uer lmt= & lower lmt=) an all the other arameters of regulator are set to zero value. g : Increase the value of ths arameter wll ten to ecrease the steay state level as shown n fgure (8). Fgure (8) shows the resonses of fferent values of arameter g wth the resent of excter saturaton (uer lmt= & lower lmt=), arameter t =1 an all other the arameters of regulator are set to zero value. g 1 : Increase the value of ths arameter wll ten to ecrease the over shoot as shown n fgure (9). Fgure (9) shows the resonses of fferent values of arameter g 1 wth the resent of excter saturaton (uer lmt= & lower lmt=), arameter t =1, arameter g =9, an all the other arameter of regulator are set to zero value. From ths stuy we observe the rest controller arameters (t 1,t,r 1, an g ) have no a valuable effect on the resonse. So they are not tune an set to zero. When the TMRAC examne wth unt ste nut, secon orer reference moel (.7 amng rato an 4 ra/secon natural freuency), an excter saturaton (uer lmt = &lower lmt=). The obtane results for fferent loas (heavy=1.9ma, meum=1ma, lght=.1ma) are accorng to the followng cases:- 6

6 Case one wth regulator arameters (t =1, g =9, g 1 =5, an t 1 =t =r 1 =g =) an no aataton (aataton gan eual to zero) the obtane resonses are ecte n fgure (1), whch shows goo resonse only wth meum loa. Case two wth the same settng of regulator arameters as n case one an aataton for omnant arameter g (aataton gan (γ) for arameter g =1 an the other arameters aataton gan sate to zero). The obtane resonses are shown n fgure (11), whch shows goo resonses for fferent loas. The aatatons of arameter g for fferent loas are ecte n fgure (1). It s clear from fgure (1) the aataton tme aroxmately four secon. The conventonal PID controller resonses wth same excter saturaton an loas are shown n fgure (13). The use gans for PID controller are (roortonal =5, ntegral =4, ervatve =). Fgure (13) shows hgh over shoot an large settlng tme comare wth TMRAC for fferent loas. Fgure(5) PID smulnk rogram for SG wth excter saturaton Table (1) arameter of SG from Matlab R8a Rate Power KA Rate voltage (L-L) 4 Rate freuency HZ 5 stator resstance u.95 Stator nuctance u.5 Quarature mutual n.u 1.51 rect mutual n. u.6 Fgure (6): Smulnk rogram of TMRAC for SG & saturaton Fel resstance u.1971 Fel nuctance u.3418 Damer resstance u.13 Damer nuctance u

7 Fgure (7): TMRAC resonse for t arameter when other arameters are zero Fgure (9): TMRAC resonses for arameter g1, g=9 an t=1 Fgure (8): TMRAC resonse for arameters g an t=1 Fgure (1): TMRAC resonse for fferent loas an aataton gan= (no aataton) 6

8 Fgure (11): TMRAC resonse for fferent loas wth aataton gan of g=1 Fgure (13): PID resonse for fferent loas Fgure (1): the aataton of arameter g for fferent loas 6. Conclusons The esgn arameters of aatve control have been nvestgate va several smulatons. The results of ths stuy can be summarze as follows: 1-Wth the novel aroach, asymtotcally stable resonse s acheve even though the lant s wth unknown ynamc euatons of hyscal system. -the regulator arameters can be tune wthout aataton (aataton gan =) untl the resonse aroxmately reachs the reference moel. 3-After the aataton mechansm works, the resonse wll be very close to the reference moel. 4-Only the omnant regulator arameters can be use. 5-The aataton mechansm can be use for only one arameter. 6-The mlementaton of TMRAC use n ths work s smle because of the reucton 63

9 n regulator arameters an the number of omnant arameters havng aataton. 7- The TMRAC has a better resonse than the conventonal PID controller for the fferent loas. 8-The contrbutons obtane from ths work are the aataton mechansm for only one arameter an only the omnant regulator arameters can be use n the TMRAC. References [1] Alreza S. (6)" A PI Controller Base on Gan-Scheulng for Synchronous Generator" Turk J Elec Engn, OL.14, NO.. [] Young F., Yunng C., Shangsheng L., Dong L., an Y. (6) " Aatve Control for Synchronous Generator Base on Pseuolnear Neural Networks" J. Wang et al. (Es.): ISNN 6, LNCS 397, Srnger-erlag Berln Heelberg 6 [3] Nubs S. N. (8) " A Fuzzy Moel Reference Learnng Controller for Synchronous Generator Termnal oltage Control" Euroean Journal of Scentfc Research ISSN X ol.4 No.3. ( EuroJournals Publshng, Inc. 8 htt:// [4] Crstea,M. N., Dnu,A., Khor J. G.,Cormck, M. M., () Neural an FuzzyLogc Control of Drves an PowerSystems, Lnacre House, JoranHll,. [5] Jung-Wook P., Ronal G. H., an Ganesh K.. (3) "Aatve-Crtc-Base Otmal Neurocontrol for Synchronous Generators n a Power System Usng MLP/RBF Neural Networks" IEEE, Transactons on Inustry Alcatons, ol. 39, NO. 5, Setember/October 159. [6] Salem M. M., Zak A. M., Malk O. P. () " Real-Tme Imlementaton Of A Neuro-AR For Synchronous Generator" 15th Trennal Worl Congress, Barcelona, San, Coyrght IFAC [7] Humo A. T. an Ameen N. M. (1) " Tunng Controller for Inucton Motor usng Moel Reference Aatve Control" Eng &Tech. Journal, ol.8,no.11. [8] Astrom K. J., Wttenmark B. () "Aatve Control", Ina. 64