Simulation and Hardware model of Induction Generator using PWM

Transcription

1 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November Smulaton and Hardware model of Inducton Generator usng PWM Saravanakumar.S S.Saravanakumar Sankar. S, S.Sankar,D.Jayalakshm, Jayalakshm.D M.Padmarasan Padmarasan.M Prof /Dept. Of IT Prof /Depart. Of EEE Asst. Prof/Dept. of EEE Asst. Prof/Dept. of EEE Panmalar Inst. of Tech Panmalar Inst of Tech, SRM Eswar Engg College Panmalar Inst of Tech Chenna, Inda Chenna, Inda Chenna, Inda Chenna, Inda was dealt by N.C. Scott []. The voltage nput of dstrbuted wnd generaton on rural dstrbuton feeder was presented by Abstract A varable speed cage type Inducton Generator system s smulated and mplemented. The complete model conssts of Inducton Generator, PWM converter, PWM nverter and local load. The system studed mantans constant voltage when the speed s fluctuatng. The advantages of PWM rectfer and PWM nverter are utlzed. Crcut model for varable speed nducton generator s developed and the smulaton studes performed on the crcut model for varable speed cage machne wnd generaton unt show that the output voltage s constant even as the load changes. Index Terms Inducton generator, wnd power generaton, wnd energy, Voltage control, mcro controller.. INTRODUCTION In recent years wnd power generaton has experenced a very fast development n the entre world. Wnd power provdes an addtonal source of energy for power corporatons and state electrcty boards. Wth the advent of large scale wnd farms, utltes are fndng t attractve and cost effectve to purchase wnd power. Wnd power s envronmentally frendly and enjoys postve publc acceptance. It provdes a hedge aganst spralng ncrease n fuel prce. Varable speed operaton s ntroduced to gan hgh effcency n the generatng system. Otherwse the generatng system cannot capture the largest possble energy avalable n the wnd comprehensve control strategy for varable speed cage machne wnd generator unt s gven n ths analyss. Ths paper has dscussed the control of local bus voltage to avod voltage rse. Smth [4]. A method of trackng the peak power pont for the varable speed wnd energy converson system was gven by V.T.Ranganathan [5].. THE WIND TURINE SYSTEM The block dagram of varable speed Inducton Generator system s shown n Fg.. The system has Inducton Generator (IG), PWM rectfer, PWM nverter and the local load. The modelng of each block s dscussed and the overall model s used for smulaton. IG s represented as varable frequency source n the smulaton. PWM. Rectfer converts ac nto dc. The dc output s fltered usng the capactor flter. The rectfer and the capactor flter acts as voltage source at the nput of PWM nverter.the PWM nverter converts dc nto constant frequency of ac. The output frequency s constant snce the MOSFETs are trggered at constant power frequency. The PWM output has very low harmoncs snce snusodal pulse wdth modulaton s employed. The smulaton was done usng nonlnear model for varable speed nducton machne. Growth of worldwde wnd generaton capacty as compared wth nuclear capacty was dealt by C.R.De Azua [].The varable speed wnd power generaton usng doubly fed wound rotor nducton machne was dealt by R.Datta [].The use of load controlled regulated voltage on dstrbuton networks wth embedded generaton Fg.. lock dagram of varable speed nducton generator system. ANALYSIS OF HYRID SYSTEM The objectve of the optmzaton model s to optmze the avalablty of energy to the loads accordng to ther levels of prorty. It s also proposed to mantan a far level of energy storage to meet peak load demand, demands durng low or no radaton perods, or wnd speed s very less. The loads are classfed as prmary and deferrable loads. Machnes used to produce power from the wnd are usually classfed nto two dfferent groups: horzontalaxs and vertcalaxs machnes []. In order to develop a model to 4

2 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November any one of the machne groups, etz theory [] s usually used. etz assumes that the wnd rotor s deal and that s to say; t has no hub and an nfnte number of blades offerng no resstance drag to the passage of ar. Moreover, the condtons over the whole area swept by the wnd rotor are supposed to be unform and the speed of the ar through and beyond the rotor s assumed to be axal. The power of the movng ar through the wnd rotor can be expressed as []: Po A rvw () A r represents the swept area by the motor rotor and t wll be set n ths nvestgaton to A r = r. r represents the radus of the rotor. : densty of the ar whch may be taken at normal temperature and pressure as equals to.5 kg/m V w : s the wnd speed n meter/second (m/s). The movng ar power (P o ) can be converted partally to a mechancal power. The mechancal power that can be Pw ArVwC p extracted from such movng ar power can be expressed as []: Where C p s a dmensonless performance power coeffcent and ts value s naturally always. There s no radcal theoretcal bass that can lead to the development of () a well defned analytcal expresson for the power coeffcent C p. x 6 ( ) C C C C C p C p C e () Investgators [] dealng extensvely wth the subject of wnd energy have proposed a handy formula or expresson of the form: Where C =.5, C = 6/, C =.4, C 4 =.,C 5 =5, C 6 =/, x=.5. p / P P C w o p.8p p r w V w : angular velocty of the wnd motor (rad/sec) V w : wnd speed (m/s) r: radus of the rotor of the wnd motor (m) p: ptch angle between the blade element wth respect to the plane of rotaton. Such an angle s fxed n ths nvestgaton and s set to be equal to /8 radan. : s known as the tp speed rato. Examnng equaton, one can deduce that for each possble wnd speed, the extracted wnd power (P w ) can be maxmzed when the power coeffcent C p s maxmzed. The w (4) power coeffcent C p attans ts maxmum when the condton dc p /d = s satsfed. Such condton s reached and can be checked when the tp speed rato s equal to The correspondng value of the coeffcent C p at such tp speed rato s C p,max = Thus, for the sake of extractng maxmum wnd power (P w,max ) at a certan wnd speed (V w ), the wnd motor speed has to be controlled and made rotatng at the followng angular * Vw w r velocty: The maxmum extracted wnd power s of the form: It s desred to mnmze, dumped energy, Q dump ( t ). The dumped energy s the excess energy, or energy whch cannot be utlzed by the loads. The objectve functon s to Maxmze 4 t P. I t Q dump wth I t where t s hour of a partcular day t =,, 4 s load type prmary and deferrable loads P s Demand of load at tme t n KW I (t) s the fracton of tme t that the load s suppled energy. A. Load constrants The energy dstrbuton from the energy devces at perod tto each load s gven as follows: t Q W, Q G, t Q, t I t P (8) Q. P, Where Q P, Q w, Q G, Q are the energy suppled by the Hybrd energy system (PV, Wnd, Gasfer and attery respectvely).pv Array constrants Ep(t) s the sum of the energy suppled by the PV array to the loads and to the battery bank, hour t, QP, t Qp, t QP, R EP (9) where Q P,R (t) s the energy dumped by the PV array Q P, (t) s the energy suppled by the PV array to the battery bank Pw,max A rvw Cp,max A rvw E a K a w (6) (7) 5

3 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November Snce energy generated by the system vares wth nsolaton, therefore the avalable array energy Ep(t) at any partcular tme s gven by E P VS( t) () Where V s the capacty of PV array S(t) s the nsolaton ndex C. Wnd energy system constrants E W (t) s the sum of the energy suppled by the wnd energy system to the loads and battery bank at hour t, QW, t Qp, t QW, R EW () (5) Kaw Pelec EaIa Ra RL where Q w,r (t) as the dumped energy by the wnd energy system D. Gasfer constrants The energy produced by the Gasfer Q G s dstrbuted to the loads and battery ank respectvely, wth a possblty of excesses. It desre to run the generator at ts Optmum capacty to ensure longevty and effcency QG, QG, QG, R QG () where Q G,I (t) s the energy suppled by the gasfer to the loads Q G, (t) s the energy suppled by the gasfer to the battery bank Q G,R (t) k the dumped energy from the gasfer Q G s the maxmum capacty of the generator Q G,, QG,, QG, R E. attery bank constrants The battery serves as an energy source entty when dschargng and a load when chargng. The net energy balance to the battery determnes ts stateofcharge, (SOC) the state of charge s expressed as follows Q SOC t) Q SOC( t ) ( Q Q Q ) Q ( P G W, where Q s the capacty of the battery bank (4) The battery has to be protected aganst overchargng; therefore, the charge level at (t) plus the nflux of energy from the PV, wnd and gasfer at perod (tl), (t) should not exceed the capacty of the battery. Mathematcally, Q Q SOC( t ) Q Q Q (5) P It s also necessary to guard the battery aganst excessve dscharge. Therefore the SOC at any perod t should be greater than a specfed mnmum SOC, SOC mn SOC( t) SOC (6) F. Dumped energy mn From the above equatons the total dumped energy n each hour t as follows Q t) Q Q Q ( ) (7) p, R ( G, R W, R dump t. SIMULATION RESULTS The smulaton crcut model for VSIG system s shown n Fg.. The MOSFETs n the sem rectfers are represented as the swtches S and S. The swtches S and S are voltage controlled swtches. The output of the rectfer s fltered usng the Capactor C. The MOSFETs of the nverter are represented usng the voltage controlled swtches. Two MOSFETs are adequate n rectfer snce one MOSFET and dode come n seres. The controlled crcut used for generatng the pulses s shown n Fg. (a) and Fg. (b). The PWM nverter output s shown n the Fg. (c). The frequency spectrum for R load s shown n Fg. (d). The crcut model wth RL load s shown n Fg. (e). AC to AC PWM converter wth RL load s shown n Fg. (f). The frequency spectrum s shown n Fg. (g). From ths fgure t can be seen that the output voltage s an mproved PWM wave form. The above mentoned waveforms are obtaned usng transent analyss of PSPICE whch calculates all the node voltages and branch currents over a tme nterval. g g R g g G uf Fg.. AC to AC PWM converter wth R load C7 S Sg W S D8 S Sg V8 VAMPL = FREQ = 5 The Fourer s wth Rload s gven s gven n table. The total harmonc dstorton (THD) was found to be 4.%. The hgher order harmoncs were found to ncrease wth RL load. AC to AC PWMC wth RLE load s shown n Fg. (a). The THD was found to be 9.8% wth RLE load. The Fourer s wth RL load are gven n table.. S D7 6

4 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November The THD was found to be 6.5%. The nverter output voltage wth RLE load s shown n Fg. (b). V 5V S Sg S Sg U6e U5r Re k Ve MCTE.9 AND V5r V6w Vdc U4r Rr k V4r U7r.9 AND V6p Vdc MCTE V6r Fg. (a and b). Inverter and Rectfer trggerng crcut V 5V V Hz Hz Hz Hz 4Hz 5Hz 6Hz 7Hz 8Hz 9Hz V(R:,R:) Fg. (d). Spectrum for R load The moments consttute the bass for a non classcal representaton of lnear systems. The characterzaton of an mpulse response by ts moments s equvalent to the moment characterzaton of a probablty densty functon. Impulse response moments are system nvarants. Lke for a probablty Harmonc number Table.. Fourer Components wth RLoad (HZ) Fourer Normalzed 5.E.67E.E.E 4.6E.55E.5E 5.749E.44E 4.E 4.54E.79E 5.5E.447E.6E 6.E 4.95E.5E 7.5E.9E 8.7E V V V V V V V V V V V V 4ms 45ms 5ms 55ms 6ms 65ms 7ms 75ms 8ms V(R:,L:) Tme V V 4ms 45ms 5ms 55ms 6ms 65ms 7ms 75ms 8ms V(R:,R:) Tme Fg. (c). Inverter Output Voltage for R load Fg. (e). AC to AC PWM converter wth RL load V V V V V V V 4ms 45ms 5ms 55ms 6ms 65ms 7ms 75ms 8ms V(R:,R:) Tme Fg. (f). Inverter Output Voltage for RL load 7

5 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November V s shown n Fg. 4. The pulses are generated from the port of the mcrocontroller. They are gven to the drver crcut through the buffer 74LS44. 5V 5Vdc 5Vdc U MCTE Vdc Ohm MOSFET6 V uf k P.5 P.4 74LS U MCTE Vdc Ohm MOSFET5 5V V Harmonc number Hz Hz Hz Hz 4Hz 5Hz 6Hz 7Hz 8Hz 9Hz V(D5:,:4) Fg. (g). Spectrum for RL load Table.. Fourer s wth RL load (HZ) Fourer Normalzed 5.E.7E.E.E.8E.45E.5E 4.645E.8E 4.E.8E.E 5.5E.68E.6E 6.E.56E 7.494E4 7.5E.4E 6.987E g g S Sg S S Sg S MHz 4 5 P. P. AT89C5 P. P. 47uF 47uF Fg. 4. lock Dagram of Control Crcut The 5V pulses from the buffer are amplfed to V usng the drver IC IR. Two drver chps were used n the present work. Each drver IC can amplfy two pulses. Therefore two drver ICs are requred to control four MOSFETs. The other two MOSFETs are controlled usng MCTE chps. The pulses from the mcrocontroller are shown n Fg. 4(a). The output voltage of the nverter wth R load s shown n the Fg. 4(b) and that of nductve load s shown n the Fg. 4(c). The top vew of the hardware s shown n the Fg. 4(d). 9 9 Drver IC IR Drver IC IR uF 47uf Ohm Ohm Ohm Ohm uf uf MOSFET4 Vdc MOSFET MOSFET MOSFET V L R FREQ = 5 V8 VAMPL = 85V mh VAMPL = 4uF C7 g D8 D7 g V Fg. (a). AC to AC PWM converter wth RLE load Fg. 4 (a). The pulses from the mcro controller V V V V V V 4ms 45ms 5ms 55ms 6ms 65ms 7ms 75ms 8ms V(R:,V:) Tme Fg. (b). Inverter Output for RLE Voltage Fg. 4 (b). The output voltage of nverter wth Rload 4. HARDWARE IMPLEMENTATION The pulses requred for the MOSFETs are generated usng mcrocontroller 89C5. The block dagram of control crcut 8

6 Internatonal Journal of Advanced Informaton Scence and Technology (IJAIST) ISSN: 9:68 Vol.7, No.7, November [5] Datta, R.; Rangenathan, V.T.; A method of trackng the peak power pont for a varable speed wnd energy converson system, IEEE trans. Energy. Convers., vol. 8, no.,pp. 6 68, Mar.. IOGRAPHY Fg. 4 (c). The output voltage of nverter wth nductve load Dr S.SARAVANAKUMAR has more than years of teachng and research experence. He dd hs under graduate n.tech n Informaton Technology at Adhparasakth Engneerng college, Madras unversty Chenna and Postgraduate n ME n Computer Scence and Engneerng at harath engneerng college,anna unversty chenna, and Ph.D n Computer Scence and Engneerng at harath Unversty, Chenna. He has gudng a number of research scholars n the area Adhoc Network, ANN, Securty n Sensor Networks, Moble Database and Data Mnng. Fg. 4 (d). The top vew of hardware 5. CONCLUSION A complete crcut model for varable speed cage nducton generator machne wnd generator system has been developed usng Pspce and matlab. In the crcut model, nducton generator, rectfer, nverter and local load are consdered. All the control aspects of double sded pulse wdth modulaton were ncluded. The varable speed wnd generator system wth R, RL and RLE loads were smulated. From the smulaton studes t s observed that the output voltage remans constant even as the wnd speed changes. The hardware was successfully mplemented usng the mcrocontroller 89C5. The expermental results concde wth the smulaton results REFERENCES [] De Azua, C.R.; Growth n worldwde and Unted states wnd generatng capacty as compared wth nuclear capacty, Wnd Eng., vol.4, no.6, pp , Dr.S.Sankar obtaned hs.e Degree n Electrcal & Electroncs Engneerng at Sr Venkateswara College of Engneerng, from Madras Unversty and M.E (Power System) Degree from Annamala Unversty Chdambaram. He has done hs Ph.D n the area of FACTS controllers n. Hs research nterests are n the area of FACTS, Electrcal Machnes, Voltage stablty, power qualty, Power system securty and Power System Analyss. D.Jayalakshm obtaned her.e Degree n Electrcal & Electroncs Engneerng at Jaya College of Engneerng, from Madras Unversty and M.E (Power System) Degree from AnnaUnversty Chenna.. Her area of nterest s Power System Stablty, Dynamcs, Renewable Power Generaton, Hybrd Power Generaton & Hgh Voltage Engneerng. He publshed varous papers n Internatonal Journals & Conferences. Mr.M.PADMARASAN has completed hs.e. n Pryadharshn Engneerng College, Vanyambad. He completed hs M.E. (Power System Engneerng) at Annamala Unversty, Chdambaram n the year of 4. He s a Research Scholar n Sathyabama Unversty. Hs area of nterest s Power System Stablty, Dynamcs, Renewable Power Generaton, Hybrd Power Generaton & Hgh Voltage Engneerng. He publshed varous papers n Internatonal Journals & Conferences. [] Datta, R.; Ranagenathan, V.T.;, Varable speed wnd generaton usng doubly fed wound rotor nducton machne a comparson wth alternatve schemes, IEEE Trans. Convers., vol.. 7, no., pp. 44 4, sep.. [] Scott, N.C.; Atnson, D.J.; Morrel, J.E.; Use of load control to regulate voltage on dstrbuton networks wth embedded generaton, IEEE Trans. Power Syst., vol. 7, no., pp. 5 54, May. [4] Smth, J.W.; rooks, D.L.;, Voltage mpacts of dstrbuted generaton on rural dstrbuton feders, n Proc. Transm. Dstrb. Conf. Expo., vol.,, pp