Modeling and Performance Study of Single Phase Induction Motor in PV Fed Pumping System using MATLAB

Transcription

1 Interntionl Journl of Electricl Engineering. ISSN Volue 5, Nuber 3 (2012), pp Interntionl Reserch Publiction House Modeling nd Perfornce Study of Single Phse Induction Motor in PV Fed Puping Syste using MATLAB 1 N. Chndrsekrn nd 2 K. Thygrjh 1 Associte Professor, PSNA College of Engg. & Tech., Dindigul, Tilndu, Indi E-il: chndrsekrn283@gil.co 2 Principl, KSR College of Tech, Tiruchengode, Tilndu, Indi E-il: drkt52@gil.co Abstrct Wter puping using AC otors hs becoe one of the ost fesible photovoltic (PV) pplictions. Moreover, PV puping is getting ore ttention in recent dys inly in reote res where connection to the grid is techniclly not possible. Power genertion by Photovoltic is relible. The opertion nd intennce costs re low. The induction otor is ore rugged, nd intennce-free otor. In this pper, PV fed wter puping syste using single phse induction otor hs been considered. The odeling of PV cell, Boost converter, inverter nd single phse induction otor hve been studied nd developed. The overll AC puping syste fed by PV cell hs been siulted using MATLAB nd the results re obtined. The results show the perfornce of single-phse induction otor drive supplied by photovoltic genertor. Keywords: Photovoltic; Puping syste; Modelling; Mtlb Introduction Photovoltic is being eployed round the whole world in ost recent yers. It is widely used in ny pplictions in islnds nd reote res. Using photovoltic s the power source for wter puping is considered s one of the ost proising res of PV ppliction [1]. PV wter puping systes generlly consist of PV rry, controller, otor, pup nd wter storge tnk [2]. Photovoltic wter puping systes re prticulrly suitble for wter supply in reote res where the electricity

2 306 N. Chndrsekrn nd K. Thygrjh is not vilble. Wter cn be puped during the dy nd stored in tnks, king wter vilble lso t night or when it is cloudy. The puped wter cn be used in ny pplictions such s doestic use, wter for irrigtion nd villge wter supplies. PV CELL BOOST CONVERTER SINGLE PHASE INVERTER SINGLE PHASE INDUCTION MOTOR PUMP PULSE CIRCUIT SPWM GENERATOR Figure 1: PV fed AC puping syste The dvntges of using wter pups powered by photovoltic systes include low intennce, ese of instlltion, relibility nd the tching between the powers generted nd the wter usge needs. In ddition, wter tnks cn be used insted of btteries in photovoltic puping systes. Puping schees driven by d.c. otors suffer fro intennce probles. A puping syste bsed on n induction otor cn be n ttrctive proposl where relibility nd intennce-free opertion is iportnt [6]. In this pper, puping syste bsed on n induction otor driven by voltge source inverter hs been considered. The induction otor bsed photovoltic puping syste offers n lterntive for ore relible nd intennce free systes [11]. In ddition, recent dvnces in the field of solid stte devices, logic circuits nd control theory hve given gret ipetus to the use of single phse induction otors in PV systes [3]. The schetic digr of puping syste using single phse induction otor fed by PV cell is shown in fig.1. The syste consists of PV rry, d.c.-d.c, converter, voltge source inverter, nd the induction otor coupled to centrifugl pup. The pup is to convert the echnicl energy into hydrulic energy. Here, the AC puping syste powered by PV cell is siulted using MATLAB nd the perfornce of single-phse induction otor drive is obtined. PV Cell Model The physics behind photovoltic is helpful in understnding the equivlent circuits used to odel it. Photovoltic cells re seiconductor devices; the vst jority of coercil PV cells re fbricted fro silicon [4]. A PV cell is essentilly lrge diode tht produces voltge when exposed to incident light. It y be considered to be light-eitting diode run bckwrd; the nlogy is siilr to het engine nd refrigertor [8]. The PV genertor is non-liner device nd is usully described by

3 Modeling nd Perfornce Study of Single Phse Induction Motor 307 its equivlent circuit nd the I-V chrcteristics, shown in fig. 2 nd fig. 3.The electricl odel of solr cell is coposed of diode, two resistnces nd current genertor. The reltionship between the voltge V (V) nd the current I (A) is given by I V + IR V + IR S S = I L IO exp 1 (1) A R P where I L, I O nd I re the photocurrent, the inverse sturtion current nd the operting current, R S nd R P re series nd prllel resistnces, respectively, which depend on the incident solr rdition nd the cell teperture. A =KT/q is the diode qulity fctor. K nd q re Boltznn constnt nd electronic chrge respectively. Townsend (1989), Eckstein (1990), Al-Ibrhii (1996), propose the odel with four preters ssuing tht the prllel resistnce is infinite so (1) cn be rewritten s V + IRS I = IL IO exp 1 (2) A The current nd the voltge preters of the PV genertor re: I pv =I nd V pv = n s N s V, where n s, N s re the nubers of series cells in the pnel nd of the series pnels in the genertor. The PV genertor consists of solr cells connected in series nd prllel fshion to provide the desired voltge nd current required by the lod [7]. Figure 2: Equivlent circuit of PV cell Now only the four preters I L, I O, R S nd A need to be evluted, ethod to clculte these preters hs been developed by Townsend (1989) nd Eckstein(1990), Duffie nd Beckn (1991).

4 308 N. Chndrsekrn nd K. Thygrjh Figure 3: VI Chrcteristics of PV Genertor The fig. 3 shows typicl I-V chrcteristics for incresing insoltion levels of the used PV rry. The short circuit current vries in proportion to the insoltion level, while the open circuit voltge is pproxitely constnt [5]. Consequently, the extrcted electric power will increse ccordingly. Ech curve hs xiu power point, which is the optil operting point for n efficient use of the solr rry. Boost converter Model Boost converter is power electronic circuit which gives the output voltge which is greter thn the input voltge. It consists of dc input voltge source V s, boost inductor L, controlled switch S, diode D, filter cpcitor C, nd lod resistnce R.[10] When the switch S is in the on stte, the current in the boost inductor increses linerly nd the diode D is off t tht tie nd t the se tie inductor stores the energy. When the switch S is turned off, the energy stored in the inductor is relesed through the diode to the output RC circuit. Now the output voltge is su of input voltge nd the inductor voltge. The circuit digr of boost converter is shown in Fig. 4. Figure 4: Circuit digr of Boost Converter

5 Modeling nd Perfornce Study of Single Phse Induction Motor 309 Using Frdy s lw for the boost inductor V kt = (V V )(1 k)t (3) S O S fro which the dc voltge trnsfer function turns out to be VO 1 M V = = (4) V 1 k S As the ne of the converter suggests, the output voltge is lwys greter thn the input voltge. The boost converter opertes in the CCM for L > L b where L b ( 1 k) 2 kr = (5) 2f where k, is the duty rtio of dc to dc converter which is defined s the rtio of turn on tie to tht of totl tie. The boost converter steps up the voltge fro pv rry to the required vlue before feeding to the puping syste. Inverter Model Voltge source inverters re widely used in power supplies, power qulity controllers, renewble energy, rine nd ilitry pplictions. If the input dc is voltge source, the inverter is clled Voltge Source Inverter (VSI). The siplest dc voltge source for VSI y be bttery bnk or solr photovoltic cells stck. They re t the hert of pplictions requiring n AC supply fro DC source [9]. Therefore, it is iportnt tht they re designed to be robust nd efficient, especilly in reote res nd renewble energy pplictions. Fig. 5 shows the circuit topology for full bridge inverter. It is n electronic power converter tht is necessry s n interfce between the power input nd the lod. The full bridge single phse inverter consists of the DC voltge source, four switching eleents G1, G2, G3 nd G4 nd lod. The switching eleent vilble nowdys, such s bipolr junction trnsistor (BJTs), gte turn off thyristor (GTOs), etl oxide seiconductor field effect trnsistors (MOSFETs), insulted gte bipolr trnsistors (IGBTs), etl oxide seiconductor controlled thyristor (MCT s) nd sttic induction trnsistors (SIT s) cn be used s switch[9]. The full bridge single phse inverter hs two legs, left or right or A phse leg nd B phse leg. Ech leg consists of two power devices (here MOSFET) connect in series. The lod is connected between the idpoints of the two phse legs. Ech power control device hs diode connected in nti-prllel to it.

6 310 N. Chndrsekrn nd K. Thygrjh Figure 5: Circuit digr of Single phse Inverter The diodes provide n lterntive pth for the lod current if the power switches re turned OFF. For exple, if lower MOSFET in the A phse leg is conducting nd crrying current towrds the negtive DC bus, this current would coutte into the diode cross the upper MOSFET of the A phse leg, if the lower MOSFET is turned OFF. Control of the circuit is ccoplished by vrying the turn on tie of the upper nd lower MOSFET of ech inverter leg with the provision of never turning ON both t the se tie, to void short circuit of DC bus. The control pulse to the swtches y be generted by either icrocontroller or DSP. The rs output voltge cn be found fro V O 1/ 2 2 TO / 2 2 = V 0 S dt = VS T (6) O A vrible voltge cn be obtined by vrying the input dc voltge nd intining the gin of the inverter constnt. On the other hnd, if the dc input voltge is fixed then vrible output voltge cn be obtined by vrying the gin of the inverter. This cn be ccoplished by Pulse Width Modultion-PWM control within the inverter. PWM ens the width of the squre pulse in positive nd negtive hlves cn be djusted ccording to the rs of the output required. The inverter gin y be defined s rtio of the c output (rs) voltge to dc input voltge. Here, the input to the inverter is supplied fro boost converter nd expected output voltge is 230V.

7 Modeling nd Perfornce Study of Single Phse Induction Motor 311 Induction Motor Model The equivlent circuit of the induction otor bsed on double revolving field theory is shown in Fig. 6 where is the turns rtio of the uxiliry to in winding R l, X l re the resistnce nd rectnce of the in winding, R l, X l re the resistnce nd rectnce of the uxiliry winding, R c, X c re the equivlent series resistnce nd rectnce of the cpcitor, R f, X f re the forwrd equivlent series resistnce nd lekge rectnce of the rotor referred to the in winding, R b, X b re the bckwrd equivlent series resistnce nd lekge rectnce of the rotor referred to the in winding, I, I, I re the in, uxiliry nd otor currents, respectively, E f, E b re the self induced voltges in in winding by its forwrd nd bckwrd fluxes, respectively, E f, E b re the utully induced voltges in uxiliry winding by its forwrd nd bckwrd fluxes of the in winding, respectively, E f, E b re the self induced voltges in uxiliry winding by its forwrd nd bckwrd fluxes, respectively, E f /, E b / re the utully induced voltges in in winding by its forwrd nd bckwrd fluxes of the uxiliry winding, respectively[13]. Figure 6: Equivlent circuit of Induction Motor Fro fig. 6, the following equtions re written V = Z I + E + E je / je / (7) I f b f + V = (Z + Z )I + E + E + je je (8) I c fb b f b b where, E E = Zf I = I (R f jx f ) (9) = Z I = I (R jx ) (10) + b b b + b

8 312 N. Chndrsekrn nd K. Thygrjh E E 2 2 = Zf I = I (R f jx f ) (11) 2 2 = Z I = (I (R jx ) (12) f + b b b + Substituting fro equtions (9)-(12) into equtions (7) nd (8) gives b V = (Z + Z + Z )I j(z Z ) I (13) l f b f b 2 V j(zf Zb )I + (Zl + Zc + (Zf + = Z )) I (14) The solution of equtions (13) nd (14) gives the in nd uxiliry winding currents under ny operting conditions. Hence, the totl otor current is obtined s I = I + I (15) The net ount of power trnsferred cross the ir gp is obtined s P = (I + I )(R R ) + 2I I (R + R )sin( θ θ ) (16) g f b Where θ nd θ re the phse ngles of the in nd uxiliry winding currents, respectively. The electro echnicl torque developed is T = P ω (17) d g / s Where ω s is the synchronous speed in rd/sec. The echnicl power developed is given by P = (1 S) (18) d P g where S is the per unit slip. The output power is P = P P (19) o d rot Where, Prot is the rottionl losses. The voltge equtions (13) nd (14) constitute the stedy stte ode of the single phse induction otor. The solution of these equtions under ny operting conditions gives the in nd uxiliry winding currents. Hence, ll the perfornce chrcteristics of the otor t prticulr lod point cn be clculted.it should be noted tht prticulr lod point ens given vlue for the pplied voltge nd otor speed. f b b Centrifugl Pup Model There re two types of pups coonly used for wter-puping pplictions. One is positive displceent pup nd nother is centrifugl pup. Displceent pups hve wter output directly proportionl to the speed of the pup, but lost independent of hed. These pups re used for solr wter puping fro deep wells

9 Modeling nd Perfornce Study of Single Phse Induction Motor 313 or bores[9]. Centrifugl pups re used for low-hed pplictions, especilly if they re directly interfced with the solr pnels. Centrifugl pups re designed for fixedhed pplictions, nd the pressure difference generted increses in reltion to the speed of the pup[10]. These pups re of the rotting ipeller type, which throws the wter rdilly ginst csing shped so tht the oentu of the wter is converted into useful pressure for lifting [12]. The centrifugl pups hve reltively high efficiency, but it decreses t lower speeds, which cn be proble for solr wter-puping syste t ties of low light levels. In fct, in the cse of the centrifugl pups, the opertion tkes plce for longer periods even for low insultion levels, nd the lod chrcteristic is in closer proxiity to the PV xiu power locus. Any pup is chrcterized by its bsorptive power which is obviously echnicl power on the shft coupled to the pup, which is given by [5] ρ P = ghq (20) η Useful power: power consued of the bsorptive power is given by P u = ρghq (21) where η, the totl output; ρ, density (Kg/ 3 ); G, ccelertion of grvity ( 2 /S); H, height of rise (); Q, flow( 3 /S). Siultion circuit And Results The siultion circuit odel of AC puping syste fed by photovoltic rry is shown in Fig. 7. The solr cell is generting 40V. The output voltge fro the solr rry is incresed to the required level by ens of boost converter. The output voltge fro boost converter is 230V.As the nuber of switches in the boost converter is less; it is econoicl when copring with other type of dc to dc converters. Here, the MOSFET bsed boost converter is used which is powered by PV rry. The PWM technique is used to generte the triggering pulse to the MOSFET. The Micro controllers or DSPs cn be used to generte the triggering pulses prcticlly to the swithes of boost converter nd the inverter. Figure 7: Siultion circuit odel of AC puping syste

10 314 N. Chndrsekrn nd K. Thygrjh The output current nd voltge of the boost converter re shown in the Fig. 8 nd Fig. 9 respectively. The high efficiency, non pulsting input current, high pek trnsistor current nd output voltge sensitive to duty rtio re soe fetures of boost converter. The output of the boost converter is given s input to the single phse bridge type inverter. The output voltge of the inverter is 230V. The output voltge of the inverter is shown in the Fig. 10. The output of the inverter is fed to the AC otor to which the centrifugl pup is coupled. Figure 8: Output current of boost converter Figure 9: Output Voltge of boost converter Figure 10: Output Voltge of Inverter

11 Modeling nd Perfornce Study of Single Phse Induction Motor 315 The centrifugl pup with 20 hed is selected for this work. The rtings of single phse induction otor re s follows. Tble No.1: Specifictions of Single phse induction otor Preters Power Voltge Current speed Vlue 0.5 hp 230v AC 1.5 A 3000 rp The siultion results give the ide to go for the experientl set up of the c puping syste. In reote res where the power supply fro grid is not possible, this type of puping syste is ore suitble. The wter cn be stored in the tnks for the use t night tie. Or otherwise the energy cn be stored in the bttery nd y be utilized when the sunlight is bsent. This kind of solr bsed puping syste is ore efficient for low power pplictions. Figure 11: Siultion outputs for speed, rture current nd torque The siultion outputs of single phse induction otor re shown in fig.11.the speed, torque nd current output of the induction otor clerly indictes tht it is very uch suitble for c puping syste. Conclusion The work siulted in this pper exines the possibility of utilizing PV cell to supply single-phse induction otor through single-phse bridge inverter. The syste explined here is PV syste for wter puping, using single phse inverter nd single phse induction otor. We cn conclude tht this work will be contribution to the nlysis of the photovoltic puping syste with regrds to the results of siultion of the odel. This pper lso investigtes photovoltic

12 316 N. Chndrsekrn nd K. Thygrjh powered AC otor drive for wter puping ppliction nd rurl electricity. A nuber of experientl PV powered DC otor drives for wter puping re lredy in use, however such schees find liited pplictions due to high cost nd intennce probles coonly ssocited with DC chines. The experientl setup nd its nlysis y be considered s the future work. References [1] Nejib Hrouni, Moncef Jridi, Adnene Cherif Theoreticl nd experientl nlysis of the behvior of photovoltic puping syste Science direct, Solr Energy 83 (2009); [2] Odeh I, Yohnis YG, Norton B.Influence of puping hed, insoltion nd PV rry size on PVwter puping syste perfornce.solr Energy 80 (2006) ; [3] A Betk, A. Moussi Perfornce optiiztion of photovoltic induction otor puping syste Science direct, Renewble Energy 29 (2004) [4] Benlrbi K, Mokrni L, Nit-Sid MS. A fuzzy globl efficiency optiiztion of photovoltic wter puping syste.science direct, Solr Energy 77 (2004); [5] Arrouf M, Ghbrour S.Modelling nd siultion of puping syste fed by photovoltic genertor within the Mtlb/Siulink progring environent. Science direct, Deslintion 209 (2007) ; [6] Nng Sw Yuzn Kying, Wunn Swe Design Considertions of PV Wter Puping nd Rurl Electricity Syste (2011) in Lower Mynr. World Acdey of Science, Engineering nd Technology 75, [7] Rchid Chenni, Lid Zrour, Aiss Bouzid, Abdelhli Borni Iproveent of Synchronous nd Asynchronous otor drive systes supplied by Photovoltic Arrys with frequency control. Journl of Elecricl Engineering, Vol. 59, No. 4, 2008, [8] Mkbul Anwri M. Irn Hid, nd Tufik Power Qulity Behvior of Single Phse Fed Adjustble Speed Drive Supplied fro Grid of PV Genertion.2nd IEEE Interntionl Conference on Power nd Energy (PECon 08), Deceber 1 3, Johor Bhru, Mlysi. [9] Muhd H.Rshid. Power Electronics circuits, devices, nd Applictions.3rd edition.personeduction, [10] Mehet AkbbMtching induction otors to PVG for xiu power trnsfer Science direct, Deslintion 209 (2007) ; [11] B.L. Therj, A.K. Therj.A Textbook of Electricl Technology: Vol 2. AC nd DC Mchines, S.Chnd&copny Ltd, Newdelhi. [12] A. Hidt, B. Benyoucef Mthetic odels of photovoltic otor-pup systes.science direct, Renewble Energy 33 (2008) [13] K.Siduri, KThnushkodi Digitl siultion of Electronic trnsforer bsed single phse induction otor drive Interntionl journl of coputer nd network security, Vol.2 No.1 Jn. 2010