Analysis, Voltage Control and Experiments on a Self Excited Induction Generator

Transcription

1 Analy, Voltage Control and Experment on a Self Excted Inducton Generator Brendra Kumar Debta, Kanungo Barada Mohanty Department of Electrcal Engneerng Natonal Inttute of Technology, Rourkela-7698, Inda e-mal: bkbren@gmal.com, dr.kbmohanty@redffmal.com Abtract. In th paper dynamc analy, cloed loop oltage control and experment on a elf excted nducton generator are preented. Electromagnetc torque, acte power and reacte power are controlled under dynamc condton of ared load, exctaton capactance and haft peed, A cloed loop oltage control cheme ung a PWM Voltage Source Conerter (VSC), lnk capactor and a P-I oltage controller propoed and mplemented. Th cheme generate contant oltage and arable frequency ung the conerter whch alo act a a reacte power compenator. The frequency of tator oltage and current ared by changng the error proportonal gan makng t attracte for wnd energy coneron ytem. The mulaton done ung MATAB enronment and the expermental reult are alo preented n th paper. Key word Self excted nducton generator (SEIG), nuodal pule wdth modulaton (SPWM), reacte power compenaton, oltage control, wnd energy coneron ytem. 1. Introducton Wndy area, waterfall, reeror, hgh tde locaton are extremely helpful for generatng clean and economcal electrcal energy by proper harneng mechanm. Throughout the globe n lat three to four decade generaton of electrcty out of thee renewable ource ha created wde nteret. Growng nteret n water management and utanable enronment toward a utanable world ha awaken new ource of hydro energy. Among thee are the run-of-rer plant to produce electrcty ung nducton generator. The nducton generator elf exctaton phenomena reewed n [1]. The bruhle contructon, robutne, low mantenance requrement, abence of DC power upply for feld exctaton, mall ze, elf protecton agant hort crcut are the adantage of aynchronou generator oer the ynchronou and DC generator. The relately poor oltage and frequency regulaton and low power factor are t weaknee [1]. The frequency and magntude of oltage generated by the elf excted nducton generator (SEIG) completely goerned by the rotor peed, the exctaton and the load []. There ext mnmum and maxmum capactance for the elf exctaton to occur.e., oltage buld up at a partcular peed. Alo t requre a mnmum cut n peed for ucceful oltage buld up and t ha a maxmum peed lmt conderng mechancal afety for a fxed exctaton capactance [3-4]. The effect of dynamc mutual nductance on oltage buld up proce of SEIG ued n [5]. The applcaton of power emconductor dece, controlled conerter crcut, and control algorthm ha reulted n utable regulatng cheme for elf excted arable peed qurrel cage generator. From the electrcty company tandpont, accurate control of oltage and frequency can lmt the electrcal and mechancal tree n the power ytem and deler good qualty energy. Already many crcut are propoed to control the output oltage and/or frequency [6,7,8]. Dynamc performance of SEIG feedng dfferent tatc load ued n [9]. Contant oltage operaton ung optmzaton tool ued n [1]. The aboe paper dd not menton the effect of peed, exctaton capactance, mutual nductance on dynamc power araton and frequency of power exchange and lne oltage. Th paper explot the poble way to generate electrcal power by analyzng the machne at loaded and ared peed condton to extract the nformaton regardng dynamc acte power, reacte power and torque araton. The ablty of a contant oltage and arable frequency generaton cheme analyzed. Expermental reult are preented. A wnd peed tattcal n nature, th cheme could be extended to a arable peed, contant oltage and arable frequency wnd energy coneron ytem.. Dynamc Analy of SEIG A three phae nducton machne can operate a a SEIG f a utable capactor bank connected acro t termnal and rotor peed uffcent to hae a negate lp when dren by a prme moer. Capactor bank prode the neceary magnetzng current to tart the oltage buld up proce whch determned by feedng the machne a an nducton motor wthout load and meaurng the current a a functon of the termnal oltage araton. A complete dynamc equaton of SEIG nolng an R load n tatonary reference RE&PQJ, Vol.1, No.9, May 11

2 frame deeloped and repreented n a tate pace matrx form gen n Equaton 1. d q dr p qr d q d q R R r m r m m r r m R r mr Rr m r R R m m r r m m RS m r Rr m K 1 CK 1 CK 1 CK 1 CK 1 K R K 1 K m r m r d q R K d q dr qr d q d q ( 1) Where d, dr, q, qr are repectely the tator and rotor current n drect and quadrature ax and d and q are the ntal drect ax and quadrature ax appled oltage and K () 1 ( m 1 ) A the magnetzng charactertc nonlnear n nature, the magnetzng current found for each teraton n term of tator and rotor current a I {( ) ( ) } (3) 1 m d dr q qr The magnetzng nductance calculated from the expermentally plotted magnetzng charactertc relaton between V g and I m, through cure fttng to fnd the contant n the nonlnear equaton and gen by [11]: m (.16 exp(.56 Im)).71 (4) The per phae acte and reacte power gen by the relaton: P 1 ( dd q q ) (5) Q 1 ( qd d q ) (6) Deeloped electromagnetc torque relaton gen by: Te (3 P / 4) m ( qdr d qr ) (7) d-q tatonary reference frame to abc phae tranformaton gen by the relaton: (8) a q (1 )* ( 3 )* (9) b q d (1 )* ( 3 )* (1) c q d 3. Experment on Self-Excted Inducton Generator Schematc dagram for SEIG hown n Fg.1. Magnetzaton charactertc expermentally plotted for the 1 hp, 5 Hz nducton machne whoe detal are gen n Appendx A., by mong the haft of the machne by a hunt motor. It hown n Fg.. Mutual nductance a a functon of magnetzng current alo expermentally determned and hown n Fg.3. Operatng pont hould be choen n the negate lope zone known a table operatng regon. Prme Moer SEIG Capactor Bank oad Fg. 1. Self excted nducton generator ytem I m Fg.. Magnetzaton charactertc of nducton machne under conderaton m (H) V g I m Fg.3. Varaton of Mutual Inductance wth Magnetzng Current Photograph of the expermental etup hown n Fg.4. The ocllogram of tator oltage durng a oltage buld up proce hown n Fg.5. In th cae prme moer peed et at 1115 rpm. Stator oltage taken through a 1:1 probe. Ocllocope ettng are 13.6 V/d and m/d. At th peed of 1115 rpm, SEIG loaded ung a lamp load of W/phae. The correpondng tator oltage waeform hown n Fg.6, wth ame ocllocope ettng a n Fg.5. The tator oltage waeform durng a buld up proce at 144 rpm hown n Fg.7. The tator current waeform when t loaded wth W/phae hown n Fg.8. Stator oltage 1 RE&PQJ, Vol.1, No.9, May 11

3 waeform durng a buld up proce at 175 rpm hown n Fg.9. Fg.1 how that for low alue of peed (n th cae 19 rpm), the oltage collape and fal to buld up. V Fg.1. Voltage could not buld up and collape for a prme moer peed of 19 rpm The ratng of capactor bank.6 kvar, 415V, 5.1A. Each of three capactance alue come out to be 48µF. V Fg.4. Expermental et-up Fg.5. The oltage buld up at a prme moer peed of 1115 rpm V Fg.6. Stator oltage wth a W/phae lamp load at a prme moer peed of 1115 rpm V 4. Voltage Control of SEIG A oltage control cheme for SEIG hown n fg.11. The nducton machne for lnk oltage control modeled n tatonary reference frame. Inducton machne, pule wdth modulated oltage ource nerter, lnk capactor and load, each component of the cheme modeled eparately. A 4 V battery ued for a perod of econd for upplyng the neceary magnetzng current through a pule wdth modulated oltage ource nerter to etablh flux n the ar gap requred for elf exctaton. A DC lnk capactor of 5µF n parallel wth the dode mantan the oltage at et alue. The oltage acro the lnk capactor ened and compared wth the reference output oltage and paed through a reet PI controller. The output of PI controller conerted to three phae reference waeform and compared wth a 5 khz trangular carrer to generate the nuodal modulated gate pule. The oltage ource nerter act a a reacte power compenator. The wtchng ntant are tracked by the PI controller from SEIG. The power flow to lnk capactor through a three phae dode brdge conerter and the nput power to SEIG through a three leg IGBT conerter. Fg.7. The oltage buld up proce for a prme moer peed of 144 rpm A B C V Fg.8. For a W/phae lamp load the phae a current wth prme moer peed of 144 rpm V Fg.9. Voltage buld up at a prme moer peed of 175 rpm Fg.11. A oltage control cheme for Self-Excted Inducton Generator The oltage ource nerter modeled a : a SF1 a An n( n t ) (11) n 1 RE&PQJ, Vol.1, No.9, May 11

4 bo co SF 1b SF 1c n 1 n 1 A n( n t 1 ) (1) n A n( n t 1 ) (13) The lnk capactor modeled a : d (14) dt C S S S (15) a ea b eb c ec The et pont of V mut be greater than the peak alue of the machne lne oltage n order to force the dered lne current. The oltage error at the kth ample gen by V ( k) V ( k) V (16) err ref mcal ( k) The output of the PI controller, at the kth ample expreed a ( k) ( k 1) KITampV err ( k) KP ( Verr ( k) Verr ( k 1)) (17) Where K P and K I are the proportonal and ntegral controller gan contant. The gan contant are gen n Appendx A. 5. Smulaton Reult and Dcuon MATAB code ued to pret the generated oltage from a 1 h.p. three phae qurrel cage nducton machne wth an ntal redual oltage of 1 olt rotatng at a gen peed wth approprate capactor connected at the tator termnal to prode the neceary magnetzng current to etablh the requred flux n the ar gap. The mulaton reult how that elf exctaton can be etablhed and peed on elf-exctaton netgated. Fg.1. how the oltage buld up n phae a of nducton machne wth per phae exctaton capactance of 48µF at a rotor peed of 1 rpm. It took about. econd to ettle to t teady tate oltage of 3 olt. Fg.13, Fg.14 and Fg.15 how the generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque repone. The load 5Ω and 5mH. Fg.13 for a peed of 14rpm wth exctaton capactance of 48µF. Fg.14 for a peed of 18 rpm wth 48µF exctaton capactance. Fg.15 for an exctaton capactance of 1µF, at 18 rpm peed. It can be obered from all thee fgure that a the peed ncreaed from 14 rpm n Fg.13 to 18 rpm n Fg.14 keepng the load ame at 5Ω and 5mH, the reacte power araton too ncreaed to the range of -8VAr to -1VAr from the range of - 17VAr to -VAr. In Fg.15 a the per phae capactance alue ncreaed to 1µF for a peed of 18 rpm there a conderable ncreae n the reacte power from -1VAr to -13VAr. The ncreae n acte power araton and electromagnetc torque alo n obered a a reult of ncreae n peed and per phae exctaton capactance. Reult are hown for a perod of. econd from 5 econd to 5. econd. oad gen at 4.5 econd. A the peed ncreae the oltage buld up tart early a a reult of mutual nductance araton. It reache to t aturaton alue early ncreang the teady tate oltage. A the mutual nductance depend on magnetzng current whch n turn depend on drect ax and quadrature ax current, whch contnuouly ncreang tll the oltage reache teady tate, drawng more reacte power. ne current too ncreaed. The frequency of exchange of power too ncreaed o the frequency of lne oltage and lne current a the peed ncreaed a t can be obered from Fg.13 and Fg.14. ne Voltage V I Fg.1 The termnal oltage buld up for 48µF at 1rpm Fg.13 The generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque for a rotor peed of 14 rpm for a load of 5Ω and 5mH wth C=48µF A the per phae exctaton capactance wtched to 1µF from 48µF the dtorton n lne current apparent apart from the decreae n frequency a obered from Fg.14 and Fg.15. It happen becaue of a comparate delay n aturaton of magnetzng nductance. Fg.16. how the lnk capactor oltage profle a t track the reference alue of 4 olt at RE&PQJ, Vol.1, No.9, May 11

5 about 1 econd. Fg.17 how the generated oltage, lne current, load current, acte power and reacte power and electromagnetc torque araton when the machne run at 14 rpm and excted by a lnk capactor through a pule wdth modulated oltage ource nerter wth an error proportonal gan of unty. Reult are hown between 17 econd to 18 econd for a load of 6W and 5VAr. Reacte power are between - 5VAr to -7VAr. The lne current a dtorted nuodal. Same reult are hown n Fg.18 wth error proportonal gan of.8. The lne current get a nearly nuodal hape wth an ncreaed frequency of about 15 Hz. The oltage reman contant at 4 olt. Reacte power alo ncreae. V I Fg.14 The generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque for a rotor peed of 18 rpm for a load of 5Ω and 5mH wth C=48µF V I Fg.15 The generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque for a rotor peed of 18 rpm for a load of 5Ω and 5mH wth C=1µF V C Fg.16 DC lnk capactor oltage profle for 48µF at 18rpm V I 5-5 (a) 1-1 (b). -. (c) - (d) -4 Fg.17 The generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque for a rotor peed of 14 rpm for a load of 6W and 5VAr wth lnk capactor of 5µF wth unty gan V I (a) (b) (e) (f) (e) (c) (f) Fg.18 The generated oltage, lne current, load current, acte power, reacte power and electromagnetc torque for a rotor peed of 14 rpm for a load of 6W and 5VAr wth lnk capactor of 5µF wth.8 gan (d) RE&PQJ, Vol.1, No.9, May 11

6 6. Concluon Th paper ue the operaton of an nducton machne under tandalone generatng mode and a generatng cheme for contant oltage and arable frequency by a proportonal gan control technque. A laboratory tet performed where the nducton machne controlled a a elf excted nducton generator. The dynamc analy of a elf excted nducton generator done and the effect of rotor peed and exctaton capactance obered. From the mulaton and expermentaton, t confrmed that a the capactance ncreaed at a partcular peed, oltage buld up fater and the magntude of oltage ncreae due to aalablty of more VAR. But frequency reman contant. A the peed ncreae at a fxed capactance, both magntude and frequency of generated oltage ncreae. The capacte current lmted to a alue le than the current ratng of the nducton generator. The effect of ncreaed peed and hgher capactance on dynamc reacte power araton, oltage and frequency of output oltage alo obered. The output oltage controlled to ge a contant oltage by a mple calar lnk oltage control cheme. The frequency of the current can be controlled by aryng the error gan of the rete PI controller. The PWM VSC between generator and lnk alo controlled a a tatc VAr compenator to prode VAR to the nducton generator. [6] Mutafa A. Al-Saffar, Eu-Cheol Nho, Thoma A. po, Controlled hunt capactor elf-excted nducton generator, IEEE Conference on Indutral App., ol., pp , October [7] Jayaramaah, G.V. and Fernande, B.G., Noel Voltage Controller for Stand-alone Inducton Generator ung PWM-VSI, IEEE Conference on Indutry Applcaton, ol. 1, October 6, pp.4-8. [8] Venkatea Perumal, B. and Chatterjee, Jayanta K., Voltage and Frequency Control of a Stand Alone Bruhle Wnd Electrc Generaton Ung Generalzed Impedance Controller, IEEE Tran. on Energy Coneron, ol. 3, no., June 8, pp [9] Al Neba, Rachd Ibtouen, Tooham, Dynamc performance of elf-excted nducton generator feedng dfferent tatc load, Serban Journal of Electrcal Engneerng, ol. 3, no.1, June 6, pp [1] Vadhere Shelly and Sandhu, K.S., Contant oltage operaton of elf excted nducton generator ung optmzaton tool, Internatonal Journal of Energy and Enronment, ue 4, ol., 8. [11] Smoe, M. Godoy, Farret, Felx A., Alternate Energy Sytem: Degn and Analy wth Inducton Generator, Second Edton, CRC Pre, Boca Raton, 7, Chapter 5, pp Appendx A Inducton Machne parameter Ratng of the nducton machne 1 hp, 415 V, 14.6 A, 4 pole, and t parameter are a follow: R.6837Ω; Rr.451Ω; X l X lr 1.34Ω. PI Controller Gan Contant K P 3; K I 14. Reference [1] Sngh, G.K., Self-excted nducton generator reearch-a urey, Electrc Power Sytem Reearch, 69, 4, pp [] Salama, M.H. and Holme, P.G., Tranent and teadytate load performance of tand-alone elf-excted nducton generator, IEE Proc. Electr. Power Appl., ol. 143, no.1, January 1996, pp [3] Malk, N.H. and Haque, S.E., Steady-tate analy and performance of an olated elf-excted nducton generator, IEEE Tran. on Energy Coneron, ol. EC- 1, no.3, 1986, pp [4] Malk, N.H. and Maz, A.A, Capactance requrement of elf-excted nducton generator, IEEE Tran. on Energy Coneron, ol. EC-, no.1, 1987, pp.-9. [5] Debta, Brendra Kumar and Mohanty, K.B., Analy on the effect of dynamc mutual nductance n oltage buld up of a tand-alone bruhle aynchronou generator, Procc. of Natonal Power Electronc Conference, IIT Roorkee, June RE&PQJ, Vol.1, No.9, May 11