ANN Model for Estimation of Capacitance Requirements to Maintain Constant Air-Gap Voltage of Self-Excited Induction Generator with Variable Load

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1 ISSN : 09-89(Online ISSN : 9-(Print IJCST Vo l., Is s u e, Oc t. - De c. 0 NN Model for Estition of Cpcitnce Requireents to Mintin Constnt ir-gp Voltge of Self-Excited Induction Genertor with Vrible od Rj Singh Khel, K. S. Sndhu Dept. of Electricl Engg, Sri Si Group of Institutes, dhni, Pthnkot, Punjb, Indi Dept. of Electricl Engg, Ntionl Institute of Technology, Kurukshetr, Hryn, Indi bstrct It is essentil to supply electric power t rted voltge nd frequency to the consuers for efficient nd sfe opertion of electric equipent or other pplinces under vrying conditions of lod connected in power syste. The dependence of output voltge nd frequency of Self-Excited Induction Genertor (SEIG on its speed, lod nd terinl cpcitnce poses liittions on its use in public sector utilities for power genertion. In power systes, the utility of SEIG s stnd lone chine hs strted gining iportnce when power engineers encountered difficult situtions for instlltion of trnsission nd distribution lines in the reote res due to difficult geogrphicl conditions. The probbility of reduced terinl voltge t rted or ner full lod becoe ore pronounced when power is supplied fro n isolted genertor. Thus, to keep the lod voltges t rted level under vide rnge of lod vritions, it is necessry to regulte the terinl cpcitnce to generte constnt irgp voltge (E.00 pu. In this pper n ttept is de to odel the behvior of SEIG to intin constnt ir-gp voltge using rtificil Neurl Networks (NN. The results re in good greeent with the nlyticl solution nd re verified experientlly. Keywords Self-excited induction genertor, rtificil neurl networks, terinl cpcitnce. I. Introduction The dependence of output voltge nd frequency of self-excited induction genertor on its speed, lod nd terinl cpcitnce poses liittions on its use in public sector utilities for power genertion. To bring econoic nd socil growth in hilly nd under developed res electric power is the bsic requireent tht forced the reserchers to find n lterntive sources of power genertion fro non-conventionl energy sources. Selfexcited induction genertor (SEIG s stnd lone chine hs eerged s substitute rrngeent for power genertion in hilly res utilizing wind energy. Though SEIG hs nuber of dvntges, but it suffers fro inherent poor voltge regultion due to the difference between the rective power supplied by the shunt cpcitors nd VRs required by the lod nd chine, when operted with fixed vlue of cpcitnce. The dditionl cpcitnce requireents cnnot be deterined without the knowledge of operting conditions nd perfornce chrcteristics of the chine nd its behvior under different terinl conditions. The design of thyrister phse controlled voltge regultors for optiu output voltge nd voltge regultors using thyristor-controlled inductor for cost-effective voltge regultion t vrying lods deonstrtes the role of SEIG in power syste to eet frequency sensitive lods requireents [-]. The lterntive use of synchronous condenser to eet rective power requireents tht is costlier in intennce nd opertion is o proposed []. Singh et l. [] hve developed n lgorith for clculting the nuber of cpcitor steps required to generte voltge within the specified upper nd lower liit for loding the chine up to its rted cpcity. Ojo [] concluded tht SEIG with the long shunt connections hs the tendency to operte t higher sturtion level. Insufficient cpcitnce does not llow the genertor to build up nd selection of lrger vlue of cpcitnce t prticulr speed, invites trnsients due to sudden rise in voltge on reovl of lod. i et l. [] hve used the pproxite nlysis for long shunt SEIG to estite the vlue of shunt nd series cpcitors. Reserchers hve exined the cpcitnce requireents nd perfornce of self-excited induction chines by using the bsic odel hving single prllel cpcitor for ech phse of the chine [8-9]. The single cpcitor is idel to provide the rective power required for self-excittion when the genertor supplies constnt c lod nd is driven t fixed echnicl shft speed [0]. However, ny chnges in lod or rotor speed will result in fluctuting output voltge nd frequency unless ore elborte excittion nd control strtegy is used []. For frequency regultion, it reve fro the investigtions tht the series cpcitor helps to intin output frequency with vrying rotor speed to liited extent []. The verstile fetures like universl function pproxition bility to odel non-liner nd coplex systes, lerning nd fult tolernce hve resulted in widespred pplictions of NNs in diverse fields [-]. In the proceeding sections, the estition of terinl cpcitnce requireents to intin constnt irgp voltge of SEIG using NNs is deonstrted. II. nlyticl technique to solve equivlent circuit of SEIG ow initil nd intennce cost, robust construction of induction genertor hs de the chine ttrctive for offgrid ppliction. Under this ode of opertion the rective power is supplied fro the cpcitor bnk connected cross the lod nd the chine. s ir gp voltge (E of chine re function of sturted gnetizing rectnce (X nd generted frequency (, the equivlent circuit digr is drwn with reference to rted frequency of chine thus king the resistnce preter of rotor / sttor nd lod resistnce s frequency sensitive eleents. Per Fig. : Per phse equivlent circuit of self-excited induction genertor In t e r n t i o n l Jo u r n l o f Co p u t e r Sc i e n c e & Te c h n o l o g y

2 IJCST Vo l., Is s u e, Oc t. - De c. 0 phse conventionl equivlent circuit of SEIG is shown in Fig.. The ipednces of different brnches seen fro respective nodes re given below: R Z + jx ZCD Z CE Rs + jx jx c Re Rr ZEF // jx ZEH jx + b ( EH // EF CE ( // CD Z Z Z + Z + Z Z ( The equivlent circuit results into single loop eqution: I s Z 0 For successful voltge build up, Is 0 hence Z 0 ( y seprting the rel nd iginry coponents of eqution ( nd putting seprtely equl to zero, two non-liner siultneous equtions re obtined in ters of chine preters, speed, cpcitive rectnce, lod resistnce / rectnce, gnetizing rectnce (X nd generted frequency (. Thus the equtions obtined re s under: F (, + ( ( o X X X + X + + X + +( X + + X 0 ( ( (, G X X X X o X ( The coefficients ( - 0 nd ( - 9 of two chrcteristics equtions re obtined using Sybolic Mthetics tool box in MT nd re given in ppendix I. Polynoil equtions ( & ( re solved with Newton- Rphson (NR technique to deterine the per unit vlue of sturted gnetizing rectnce (X nd generted frequency (. Per unit ir-gp voltge (E of SEIG is deterined fro its gnetic chrcteristics given in ppendix - II. Now by solving the equivlent circuit of SEIG, the nlysis of chine is siple nd stright. rnch currents, terinl voltge nd out-put power is coputed s under: - E E Ir I Rr / ( - b + jx jx I e E R e / E/ Is ZCE + ( ZCD // Z - jx / I I c s ( R / ( / + j X- Xc ( R/ + jx I s P / ( / ( / o I R R + j X- Xc Vt / E/ - Is ( Rs / + jx III. NN odel of self-excited induction genertor Interntionl Journl of Coputer Science & Technology ISSN : (Online ISSN : 9-(Print It is estblished tht excittion phenoen of SEIG is gretly influenced by the excittion cpcitnce nd speed. Siilrly when induction genertor opertes in isolted ode its terinl voltge decreses due to the decrese in ir-gp voltge due to rture rection nd dends ore rective power. Thus to intin the terinl voltge of SEIG within the perissible operting liits, the ir-gp voltge ust be copensted by ddition of rective power supplied by the cpcitor bnk. Thus for vrying lod dend, the terinl cpcitnce hs to be chnged to new vlue (C C±ΔC to generte ir-gp voltge (E.00. The proposed NN odel of SEIG is given in Fig. tht deterines the excittion cpcitnce (C required to intin constnt ir-gp voltge E.00 corresponding to gnetizing rectnce (X. The deterintion of excittion cpcitnce to intin constnt ir-gp voltge of SEIG by using NN technique is described in the next section. Fig. : NN odel of SEIG for intining constnt ir-gp voltge (E.00. Structure of NN Model of SEIG In this work, three ode of NN structure re used to chieve full pping cpbility to deterine the cpcitnce requireents to generte constnt ir-gp voltge under vrying conditions of lod. The structure of proposed NN odel of SEIG is described s under:. NN Model Is designed to hve 8-- rchitecture structure. Input lyer hs eight neurons ccounting for input vribles i.e. chine preters (R s, R r, X, X, lod dittnce (Y, lod power fctor (Pf, speed (b nd cpcitnce (C. Single hidden lyer hs eleven neurons nd the output lyer hs two neurons ccounting for two output vribles i.e. pu generted frequency ( nd gnetizing rectnce (X.. Model Is designed to hve -- rchitecture structure. Its input lyer hs five neurons ccounting for five vribles nely; un-sturted gnetizing rectnce (X u, iniu vlue of gnetizing rectnce (X in, iniu nd xiu vlue of ir-gp voltge (E in & E x nd sturted gnetizing rectnce (X corresponding to given out-put of Model-I. Hidden lyer hs seven neurons nd output lyer hs two neurons ccounting for two vribles i.e. ir-gp voltge (E.00 pu nd sturted gnetizing rectnce ( X corresponding to constnt ir- gp voltge ( E.00 pu.. NN Model Is designed to hve -- rchitecture structure. Input lyer hs four neurons ccounting for four vribles which re;

3 ISSN : 09-89(Online ISSN : 9-(Print terinl cpcitnce (C, sturted gnetizing rectnce (X corresponding to given conditions of lod, ir-gp voltge (E.00 pu nd gnetizing rectnce (X corresponding to constnt ir- gp voltge. Hidden lyer hs six neurons nd output lyer contins only one neuron ccounting for output vrible i.e. ctul terinl cpcitnce (C C±ΔC required to generte constnt ir-gp voltge (E.00 for given loding conditions.. NN trining preters Widely used supervised neurl network, the Multi-lyer Perceptron (MP is used to trin the network. The proposed NN odel of SEIG is trined with five thousnd input-output trining sples obtined fro nlyticl technique using MT progring corresponding to rndoly chosen input vribles s discussed in section II. The rnge of ll input vribles is crefully chosen which re coptible to rel life pplictions of induction chine s self excited induction genertor. The NN structure of ech odel nd trining preters re described in the Tble. When su-squre error gol is chieved, the results of NN network re tested with the vlidtion input output sples which re other thn the trining sples. On chieving sufficient ccurcy, the trining process is terinted other wise network is trined further by setting new vlue of SEE gol. IJCST Vo l., Is s u e, Oc t. - De c. 0 requireents (C C±ΔC to intin constnt ir gp voltge (E.00 of SEIG corresponding to given speed (8 rp with vrying lod is shown in Fig.. Generted frequency, output power, terinl voltge nd brnch currents of SEIG re evluted using the results obtined fro NN odel nd the vritions of these vribles with Tble : Cpcitnce requireents to intin constnt ir-gp voltge (E.00 pu with vrying lod dittnce Tble : Terinl voltge nd output power of SEIG with constnt ir-gp voltge (E.00 Tble : NN rchitecture nd trining preters. IV. Ipleenttion of NN odel for estition of cpcitnce The proposed NN odel of SEIG is ipleented to deterine the cpcitnce requireents to intin constnt ir-gp voltge under vrying conditions of lod t unity power fctor. In this cse the induction chine opertion is crried with constnt speed nd lod dittnce t unity power fctor is vried fro 0. to 0.90 pu in eight steps. To investigte the perfornce of the proposed NN odel, input dt is presented to Model-I with chine preters nd other conditions (speed 8 rp nd cpcitnce.0 icro frd nd vrying lod dittnce s entioned bove. Using trined NN, the excittion cpcitnce requireents re coputed with input dt of chine preters for speed of 8 Rp. The results obtined fro the proposed NN odel for coputtion of excittion cpcitnce requireents to intin constnt ir-gp voltge (E.00 pu with vrying lod dittnce re recorded in Tble. Using the results of NN odel, the perfornce of SEIG with reference to terinl voltge nd output power under constnt ir-gp voltge conditions is evluted. Tble gives the coprison of results obtined fro NN odel, nlyticl technique nd experientl dt of chine with vrying lod dittnce. The vrition of gnetizing rectnce nd generted frequency corresponding to given conditions of vrying lod dittnce fro 0. to 0.90 pu, speed (8 rp nd cpcitnce (.0 icro frd is shown in Fig.. Excittion cpcitnce Fig. : Effect of lod dittnce on gnetizing rectnce nd generted frequency for given terinl conditions. In t e r n t i o n l Jo u r n l o f Co p u t e r Sc i e n c e & Te c h n o l o g y

4 IJCST Vo l., Is s u e, Oc t. - De c. 0 ISSN : (Online ISSN : 9-(Print ore pronounced when power is supplied fro n isolted SEIG. Thus, to keep the lod voltges t rted level under vide rnge of lod vritions, it is significnt to regulte the exciting cpcitnce to generte constnt ir-gp voltge (E.00 pu. Using proposed NN odel, the cpcitnce requireents re evluted under vrying conditions of lod t constnt speed. The results obtined fro NN odel re in good greeent with the nlyticl solution nd re verified experientlly. It is observed tht with the chnge in exciting cpcitnce to intin ir-gp voltge t E.0 pu, the voltge regultion of SEIG reins within the tolerble liits, thus enhncing the cpbility of chine to supply power t rted lod voltge. ppendix - I Coefficients ( 0 of eqution Fo( X, Fig. : Cpcitnce requireents to intin constnt ir- gp voltge (E.00 pu with vrying lod dittnce vrying lod dittnce re verified experientlly. The closeness of results with experientl dt s shown in fig. - vlidtes the NN odel for nlysis of SEIG for vrying conditions of lod. V. Conclusions The dependence of output voltge nd frequency of SEIG on its speed, lod nd terinl cpcitnce poses liittions of its use s genertor. The probbility of reduced terinl voltge t rted or ner full lod re - ( X ( X X X X ( RrR + R e R + X Xc + X ( ReR + XcX + RsR + X ( ReRr + RsRe + RsRr X Re( X R + RrX + ReRsX X - X ( X Xc+ ReR - X ( RsR + ReR + X X c - ( RsReX - X Re( RsX + X R - XcRr( Rs + R - XcRe( R + Rs + Rr 8 - ReX Xc( R + Rs - ReRrXc( X + X - ReRsRrR 9 ReXc( Rs + R 0 X c X R ( R R e + s Coefficients ( 9 of eqution Go( X, X X ( Re + Rr + X X R + X X ( Re + R s X X X R e - X ( ReX + X R - X X ( Rs + Re b - ( X X X Re Fig. : Effect of lod dittnce on terinl voltge nd output power with ir-gp voltge (E.00 pu Fig.: Effect of lod dittnce on sttor / rotor & lod current with constnt ir-gp voltge (E.00 pu Interntionl Journl of Coputer Science & Technology - XcRe( X + X + X - R Re( Rs + R r - R ( X Xc + RsRr - Xc( RsX + X Rr + X R r - ReX ( X Xc + XcX + RsR - RrRe( X R + R X s Re( X Xc + X Xc + XcX + RsR + XcX ( Rs + R b 8 ReX ( X Xc + XcX + ( X R R R e s 9 ReXcRr( R + Rs ppendix II Mchine specifictions nd its preters: V Volts Z V / I I. p Z 9.8 oh P V I Y / Z P 9 V Y 0.00 ho

ISSN : 09-89(Online ISSN : 9-(Print IJCST Vo l., Is s u e, Oc t. - De c. 0 Mchine preters in ohs: Rs. oh X 9. oh Rr.9 oh X 9. oh R 8oh X 8oh e u Mgnetizing chrcteristics of chine (pu vlues: X <.90 E.

5 ISSN : 09-89(Online ISSN : 9-(Print IJCST Vo l., Is s u e, Oc t. - De c. 0 Mchine preters in ohs: Rs. oh X 9. oh Rr.9 oh X 9. oh R 8oh X 8oh e u Mgnetizing chrcteristics of chine (pu vlues: X <.90 E.88-0.X X <.88 & X >.90 E.9-0.0X X <.9 & X >.88 E X X >.9 E 0 References []. E. Hd, R. M. Mthur, "New generlized concept for the design of thyristor phse controlled vr copenstor", IEEE Trns. Power pprtus Systes, vol. 98, pp 9, 99. [] H. Frnk,. ndstor, "Power fctor correction with thyristor controlled cpcitors", se Jounl, vol., pp 80 8, 9. [] M.. rennen,. bbndnti, "Sttic exciters for induction genertors", IEEE Trns. Industril pplictions, vol. (, pp 8, 9. [].T Ooi, R.. Dvid, "Induction genertor / synchronous condenser syste for wind turbine power, IEE Proceeding, vol. (, pp 9, 99. [] S. P. Singh,. Singh, M. P. Jin,"Perfornce chrcteristics nd optiu utiliztion of cge chine s cpcitor excited induction genertor", IEEE Trns. Energy Conversion, vol. (, pp 9 8,990. [] O. Ojo, "Perfornce of self excited single-phse induction genertors with short shunt nd long shunt excittion connections", IEEE Trns. Energy Conversion, vol. (, pp 8, 99. [] E. i, J. Szjner, Y. urin,"voltge copenstion of n induction genertor with long shunt connection", IEEE Trns. Energy Conversion, vol. 0 (, pp 0, 99. [8] S. S. Murthy, " novel self-excited self-regulted singlephse induction genertor", Prt : sic syste nd theory, IEEE Trnsctions on Energy Conversion, vol. 8, (, pp. -8, 99. [9] D. Sutnto, C. Grnth, M. F. Rhn, "Regulted selfexcited induction genertor for use in reote re power supply", Sixth Interntionl Conference on Electricl Mchines nd Drives, pp -9, 99. [0]. Wng, J. Su,"Dynic perfornces of n isolted self-excited induction genertor under vrious loding conditions", IEEE Trnsctions on Energy Conversion, vol.(, pp.9-00, 999. [] D. Seyou, C. Grnth, M. F. Rhn,"The dynic chrcteristics of n isolted self-excited induction genertor driven by wind turbine," IEEE Trnsctions on Industry pplictions, vol.9(, pp.9-9, 00. [] E. Muljdi, J. Slln, M. Snz, C.P. utler Eld," Investigtion of self-excited induction genertors for wind turbine pplictions", Conference Record of the 999 IEEE Thirty-Fourth IS nnul Meeting, Industry pplictions Conference, vol., pp.09-, 999. [] Nrendr K. S, K. Prthsrthy, "Identifiction nd control of dynicl systes using neurl networks," IEEE Trnsctions on Neurl Networks, vol., pp. -,990. [] S. inond, J. Si, "Neurl network d control design: n MI pproch, "IEEE Trnsctions on Neurl Networks, vol. 9(, pp. -9, 998. [] shok K. Goel, S.C. Sxen, S. hnot, "Fst lerning lgorith for trining feed-forwrd neurl networks", Interntionl Journl of Syste Science, vol., no. 0, pp. 09-, 00. [] S. Jgnnthn, "Discrete-tie CMC NN control of feedbck linerizble non-liner systes under persistence of excittion", IEEE Trnsctions on Neurl Networks, vol. 0(, pp 8-, 999. Rj Singh Khel Ws born in Indi in 9. He pssed three yer diplo course (with honours in Electricl Engg. fro PSTE Chndigrh in 9, He grduted in Electricl Engg. fro Institution of Engineers, Clcutt in 98 nd did Mster s degree (with Distinction fro Punjb University, Chndigrh (Indi in the yer 990. He did his PhD in 009 fro Punjb Technicl University, Jllndhr (Indi. His jor field of study is power systes nd is working in the re of nlysis of selfexcited induction genertor using I techniques. He served s Deonstrtor / ecturer with J. R. Govt Polytechnic, Hoshirpur (Pb fro 98 to 99. He hs served s ssocite Professor t GZS College of Engg. & Technology, thind, Punjb fro 99 to 009. Presently, he is serving s Director- Principl with Sri Si Group of Institutes dhni Pthnkot, Punjb, Indi. He hs published nuerous reserch ppers in ntionl nd interntionl journ nd conferences. His reserch ppers include pplictions of rtificil intelligent techniques in powers systes. In t e r n t i o n l Jo u r n l o f Co p u t e r Sc i e n c e & Te c h n o l o g y

Steady Sate Analysis of Self-Excited Induction Generator using Phasor-Diagram Based Iterative Model

Steady Sate Analysis of Self-Excited Induction Generator using Phasor-Diagram Based Iterative Model WSS TNSTIONS on POW SYSTMS Knwrjit Singh Sndhu, Dheerj Joshi Stedy Ste nlysis of Self-xcited Induction Genertor using Phsor-Digr Bsed Itertive Model KNWJIT SINGH SNDHU & DHJ JOSHI Deprtent of lectricl