MODELING AND ANALYSIS OF A SELF EXCITED INDUCTION GENERATOR DRIVEN BY A WIND TURBINE

Transcription

1 MODELING AND ANALYSIS OF A SELF EXCITED INDUCTION GENERATOR DRIVEN BY A WIND TURBINE A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Mate of Technology In Powe Contol and Dive By CH SUBHRAMANYAM Roll No. 211EE2141 Depatment of Electical Engineeing National Intitute of Technology, Roukela Roukela-7698

2 MODELING AND ANALYSIS OF A SELF EXCITED INDUCTION GENERATOR DRIVEN BY A WIND TURBINE A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Mate of Technology In Powe Contol and Dive By CH SUBHRAMANYAM Roll No. 211EE2141 Unde The Supeviion of Pof. K.B. MOHANTY Depatment of Electical Engineeing National Intitute of Technology, Roukela Roukela-7698

3 DEPARTMENT OF ELECTRICAL ENGINEERING NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA ODISHA, INDIA CERTIFICATE Thi i to cetify that the Thei entitled MODELING AND ANALYSIS OF A SELF EXCITED INDUCTION GENERATOR DRIVEN BY A WIND TURBINE, ubmitted by M. CH SUBHRAMANYAM beaing oll no. 211EE2141 in patial fulfillment of the equiement fo the awad of Mate of Technology in Electical Engineeing with pecialization in Powe Contol and Dive duing eion at National Intitute of Technology, Roukela ian authentic wok caied out by him unde ou upeviion and guidance. To the bet of ou knowledge, the matte embodied in the thei ha not been ubmitted to any othe univeity/intitute fo the awad of any Degee o Diploma. Date: 31/12/213 Place: Roukela Pof. K. B. MOHANTY Dept. of Electical Engg. National Intitute of Technology Roukela 7698

4 ACKNOWLEDGEMENTS I would like to expe my incee gatitude to my upevio Pof. K. B. MOHANTYfo guidance, encouagement, and uppot thoughout the coue of thi wok. It wa an invaluable leaning expeience fo me to be one of thei tudent. Fom them I have gained not only extenive knowledge, but alo a caeful eeach attitude. I expe my gatitude to Pof. A. K. Panda, Head of the Depatment, Electical Engineeing fo hi invaluable uggetion and contant encouagement all though the thei wok. My thank ae extended to my colleague in powe contol and dive, who built an academic and fiendly eeach envionment that made my tudy at NIT, Roukela mot fuitful and enjoyable. I would alo like to acknowledge the entie teaching and non-teaching taff of Electical depatment fo etablihing a woking envionment and fo contuctive dicuion. CH SUBHRAMANYAM Roll. no.:- 211EE2141 M.Tech PCD

5 ABSTRACT Wind enegy i one of the mot impotant and pomiing ouce of enewable enegy all ove the wold, mainly becaue it i conideed to be non-polluting and economically viable. At the ame time thee ha been a apid development of elated wind enegy technology. Howeve in the lat two decade, wind powe ha been eiouly conideed to upplement the powe geneation by foil fuel and nuclea method. The contol and etimation of wind enegy conveion ytem contitute a vat ubject and ae moe complex than thoe of dc dive. Induction geneato ae widely pefeable in wind fam becaue of it buhle contuction, obutne, low maintenance equiement and elf potection againt hot cicuit. Howeve poo voltage egulation and low powe facto ae it weaknee. A lage penetation of wind geneation into the powe ytem will mean that poo powe quality and tability magin cannot be toleated fom wind fam. Thi pape peent modeling, imulation and tanient analyi of thee phae elf-excited induction geneato (SEIG) diven by a wind tubine. Thee phae elf-excited induction geneato i diven by a vaiable-peed pime move uch a a wind tubine fo the clean altenative enewable enegy in ual aea. Tanient of machine elf-excitation unde thee phae balanced load condition ae imulated uing a Matlab/Simulink block diagam fo contant, tep change in wind peed and andom vaiation in wind peed. i

6 CONTENTS ABSTRACT i CONTENTS ii LIST OF FIGURES v LIST OF TABLES vii CHAPTER-1 INTRODUCTION 1.1 Motivation Liteatue Review Thei Objective Oganization of thei 4 CHAPTER-2 WIND ENERGY 2.1 Souce of wind Wind tubine Vetical axi wind tubine Hoizontal axi wind tubine Powe extacted fom wind Toque developed by a wind tubine tip-peed atio powe contol in wind tubine Pitch contol Yaw contol Stall contol Summay 15 ii

7 CHAPTER-3 AXES TRANSFORMATION 3.1 Intoduction Geneal change of vaiable in tanfomation Tanfomation into a tationay efeence fame Tanfomation into a otating efeence fame Summay 21 CHAPTER-3 THE SEIG SYSTEM 4.1 Intoduction SEIG ytem configuation The Self-Excitation Phenomenon SEIG Sytem Pefomance Opeational Poblem of the SEIG Sytem Summay 26 CHAPTER-5 MODELLING OF STAND ALONE WIND DRIVEN SEIG SYSTEM 5.1 Modelling of wind tubine Modelling of elf-excited induction geneato Modelling of excitation capacito Modelling of load impedance Development of wind diven SEIG dynamic model in matlab/imulink35 iii

8 5.6 Summay 36 CHAPTER-6 RESULTS & DISCUSSION 6.1 Simulation eult Self-excitation Poce Inetion of Load Lo of Excitation due to heavy-load Inetion of Excitation Capacito Step change in wind velocity Expeimental eult 47 CHAPTER-7 CONCLUSION& SCOPE OF FUTURE WORK 7.1 Concluion Scope of Futue wok 52 REFERENCES 53 iv

9 LIST OF FIGURES Fig.2.1 Vetical axi wind tubine...7 Fig. 2.2 Hoizontal axi wind tubine (a) Upwind machine (b) downwind machine...8 Fig.2.3. Detail of a wind tubine diven powe geneation ytem..11 Fig. 2.4 Wind Tubine output toque a a function of tubine Speed...12 Fig. 2.5 Powe Coefficient (v.) Tip Speed Ratio Cuve.13 Fig 3.1 Thee-axe and two-axe in the tationay efeence fame...18 Fig 3.2 Step of the abc to otating dq axe tanfomation (a) abc to tationay dqaxeb) tationay d -q to otating d e -q e axe.2 Fig. 4.1.Schematic diagam of a tandalone SEIG..23 Fig. 5.1 Schematic d-q axe diagam of Fig. 5.2d-q model of induction machine in the tationay efeence fame.3 (a) d-axi (b) q-axi Fig.5.3 Flow chat fo dynamic of Wind Tubine model 35 Fig.6.1 SEIG Roto peed.4 Fig. 6.2 Magnetizing cuent Fig.6.3Magnetizing Inductance...4 Fig.6.4 Stato teminal Voltage Fig.6.5 Stato cuent wave fom.. 41 Fig.6.6 SEIG Stato teminal Voltage...42 Fig.6.7 Peak SEIG teminak voltage/phae..42 v

10 Fig.6.8SEIG oto peed vaiation with load 42 Fig. 6.9SEIG tato cuent wavefom.43 Fig.6.1 Vaiation of I µ with load...44 Fig.6.11 Load cuent vaiation Fig.6.12 Lo of excitation.. 44 Fig.6.13 Peak SEIG teminal voltage/phae 45 Fig.6.14 Roto peed vaation with load and addition of capacito...45 Fig.6.15 I µ Vaiation Fig.6.16 Real powe vaiation...45 Fig.6.17 Reactive powe vaiation...46 Fig.6.18 Step change in wind velocity 46 Fig.6.19 Stato voltage vaiation with tep change...46 Fig.6.2 Roto peed vaiation with Step change in wind velocity...47 Fig.6.21 I m Vaiation..47 Fig.6.22 Expeimental etup.. 48 Fig.6.23 Build up of Line Voltage.. 48 Fig.6.24 Settled voltage..49 Fig.6.25 Deceae in voltage by eleaing Load 49 Fig.6.26 Reduced voltage afte eleaing Load. 49 Fig.6.27 Inceae in voltage by eleaing Load..5 vi

11 LIST OF TABLES Table-1 Wind tubine coupled with 22kW induction machine Table-2 Induction machine 22 kw,3-phae,4 Pole ta connected, volt,5hz Table-3 Magnetizing inductance v Magnetizing cuent..38 Table-4 Wind tubine coupled with 7.5 kw induction machine. 38 Table-5 Induction machine 7.5 kw,3-phae,4 pole ta-delta connected, volt, 5 Hz Table-6 Magnetizing inductance v Magnetizing cuent..38 vii

12 CHAPTER 1 INTRODUCTION 1

13 1.1 MOTIVATION: Geneation of pollution fee powe ha become the main aim of the eeache in the field of electical powe geneation. The depletion of foil fuel, uch a coal and oil, alo aid to the impotance of witching to enewable and non-polluting enegy ouce uch a ola, tidal and wind enegy etc., among which wind enegy i the mot efficient and wide pead ouce of enegy[1].wind i a fee, clean, and inexhautible enegy ouce. The high capital cot and the uncetainty of the wind placed wind powe at an economic diadvantageou poition. In the pat fou decade method of haneing hydo and wind enegy fo electic powe geneation and the technology fo uch altenate ytem ae developed. Fom the ecent cenaio it i alo evident that wind enegy i dawing a geat deal of inteet in the powe geneation ecto. If the wind enegy could be effectively captued it could olve the poblem uch a envionmental pollution and unavailability of foil fuel in futue. The above fact give the motivation fo development of a wind powe geneation ytem which would have bette pefomance and efficiency [2]. Continuou eeach i going on taking into account diffeent citical iue in thi ecto. Induction geneato ae inceaingly being ued thee day becaue of thei elative advantageou featue ove conventional ynchonou geneato. Thee featue ae buhle ugged contuction, low cot, le maintenance, imple opeation, elf potection againt fault,good dynamic epone and capability to geneate powe at vaying peed. The mall-cale powe geneating ytem fo aea like emotely located ingle community, a militay pot o emote induty whee extenion of gid i not feaible may be temed a tand-alone geneating ytem. Potable gen-et, tand-by/emegency geneato and captive powe plant equied fo citical application like hopital, compute cente, and continuou indutial poce come unde the categoy of tand-alone geneating ytem. Self-excited induction geneato i bet uitable fo geneating electicity fom wind, epecially in emote aea, becaue they do not need an extenal powe upply to poduce the excitation magnetic field. 1.2 LITERATURE REVIEW: Seveal new fom of enewable eouce uch a wind powe geneation ytem (WPGS) and photovoltaic ytem (PV) to upplement foil fuel have been developed and integated globally. Howeve, the photovoltaic geneation ha low enegy conveion efficiency and vey cotly a compaed to the wind powe, wind geneato take a paticula place; thu, they 2

14 ae conideed a the mot pomiing in tem of competitivene in electic enegy poduction.renewable enegy integation in the exiting powe ytem [3] i the demand in futue due to the envionmental concen with conventional powe plant. Thee phae elf-excited induction geneato diven by a vaiable-peed pime move uch a a wind tubine ued fo the clean altenative enewable enegy poduction. Self-excitation poce in induction geneato make the machine fo application in iolated powe ytem [7]. Vaiou model have been popoed fo teady tate and tanient analyi of elf-excited induction geneato (SEIG). The d-q efeence fame model, impedance baed model, admittance baed model, opeational cicuit baed model, and powe equation baed model ae fequently ued fo analyi of SEIG. The oveview of elf-excited induction geneato iue ha been povided in thi poject. Diffeent containt uch a vaiation of excitation, wind peed and load have been taken into account and accodingly the effect on geneated voltage and cuent ha been analyzed. The effect of excitation capacitance on geneated voltage ha been analyzed. The dynamic d- q model deived in thi pape i baed on following aumption: contant ai gap, thee phae ymmetical tato and oto winding, inuoidal ditibution of the ai gap magnetic field i.e., pace hamonic ae neglected. Roto vaiable and paamete ae efeed to the tato winding and coe loe ae neglected. In thi pape, we develop a dynamic model of SEIG, imulate and analyze the tanient epone of elf-excited induction geneato. Alo tanient of machine elf-excitation unde thee phae loading condition ae imulated fo contant, tep change in wind peed uing a Matlab/Simulink block diagam. Alo an expeiment i conducted in lab on open loop contol of SEIG. 1.3 THESIS OBJECTIVES: The following objective have been achieved at the end of the poject. 1) To tudy about wind a a powe ouce and the mechanim of conveion of wind powe to mechanical powe and alo the vaiation of output powe and output toque with oto angula peed and wind peed. 2) To tudy the thee-axe to two-axe tanfomation applicable fo any balanced theephae ytem. 3) Study the elf-excited induction geneato unde diffeent load condition. 3

15 4) To tudy the d-q model of elf-excited induction geneatodiven by vaiable peed pime move and in paticula by wind tubine in tationay efeence fame and developing a mathematical model. 5) To analyze the effect of peed and excitation capacitance on powe vaiation and line voltage. 6) Analyze the dynamic voltage, cuent, electomagnetic toque developed by the induction geneato and geneated output powe fo a contant, tep change and andom vaiation in wind peed. 7) Expeimentally veify the open loop contol on elf excited induction geneato in the laboatoy. 1.4 ORGANIZATION OF THESIS: The thei i oganized into even chapte including the intoduction in the Chapte 1. Each of thee i ummaized below. Chapte 2: Deal with the vaiou ouce of wind enegy and type of wind tubine available. A bief idea i given about how toque and powe poduced fom wind tubine and it i followed by diffeent method of powe contol. Chapte 3: Decibe the method to convet vaiable fom thee axe to two axe and vaiable tanfomation into tationay efeence fame and alo otating efeence fame. Chapte 4: Decibe about the tand-alone Self-excited induction geneato ytem. Thi chapte initially give an idea of elf-excitation phenomena in SEIG and followed by ytem pefomance and it opeational poblem. Chapte 5: Decibe the mathematical modelling of wind tubine, elf-excited induction geneato, excitation capacito andload impedance. Chapte 6: The imulation eult of SEIG at no-load and with RL load at diffeent condition ae howed. Alo expeimental eult of SEIG with open loop contol ae included in thi chapte. Chapte 7: Reveal the geneal concluion of the wok done and the efeence. 4

16 CHAPTER 2 WIND ENERGY 5

17 2.1 WIND SOURCES Wind i a eult of the movement of atmopheic ai. Wind come fom the fact that the egion aound the equato, at latitude, ae heated moe by the un than the pola egion. The hot ai fom the topical egion ie and move in the uppe atmophee towad the pole, while cool uface wind fom the pole eplace the wame topical ai. Thee wind ae alo affected by the eath otation about it own axi and the un. The moving colde ai fom the pole tend to twit towad the wet becaue of it own inetia and the wam ai fom the equato tend to hift towad the eat becaue of thi inetia. The eult i a lage counteclockwie ciculation of ai team about low-peue egion in the nothen hemiphee and clockwie ciculation in the outhen hemiphee. The eaonal change in tength and diection of thee wind eult fom the inclination of the eath axi of otation at an angle of 23.5 o to the axi of otation about the un, cauing vaiation of heat adiating to diffeent aea of the planet [4]. Local wind ae alo ceated by the vaiation in tempeatue between the ea and land. Duing the daytime, the un heat landmae moe quickly than the ea. The wamed ai ie and ceate a low peue at gound level, which attact the cool ai fom the ea. Thi i called a ea beeze. At night the wind blow in the oppoite diection, ince wate cool at a lowe ate than land. The land beeze at night geneally ha lowe wind peed, becaue the tempeatue diffeence between land and ea i malle at night. Simila beeze ae geneated in valley and on mountain a wame ai ie along the heated lope. At night the coole ai decend into the valley. Although global wind, due to tempeatue vaiation between the pole and the equato, ae impotant in detemining the main wind in a given aea, local wind have alo influence on the lage cale wind ytem. Meteoologit etimate that about 1% of the incoming ola adiation i conveted to wind enegy. Since the ola enegy eceived by the eath in jut ten day ha enegy content equal to the wold entie foil fuel eeve (coal, oil and ga), thi mean that the wind eouce i extemely lage. A of 199 etimation, one pecent of the daily wind enegy input, i.e..1% of the incoming ola enegy, i equivalent to the wold daily enegy conumption [5]. It i encouaging to know that the global wind eouce i o lage and that it can be ued to geneate moe electical enegy than what i cuently being ued. 6

18 2.2 WIND TURBINE A wind tubine i a tubine diven by wind. Moden wind tubine ae technological advance of the taditional windmill which wee ued fo centuie in the hitoy of mankind in application like wate pump, cuhing eed to extact oil, ginding gain, etc. In contat to the windmill of the pat, moden wind tubine ued fo geneating electicity have elatively fat unning oto. In pinciple thee ae two diffeent type of wind tubine: thoe which depend mainly on aeodynamic lift and thoe which ue mainly aeodynamic dag. High peed wind tubine ely on lift foce to move the blade, and the linea peed of the blade i uually eveal time fate than the wind peed. Howeve with wind tubine which ue aeodynamic dag the linea peed cannot exceed the wind peed a a eult they ae low peed wind tubine. In geneal wind tubine ae divided by tuctue into hoizontal axi and vetical axi Vetical axi wind tubine The axi of otation fo thi type of tubine i vetical. It i the oldet epoted wind tubine. It i nomally built with two o thee blade. A typical vetical axi wind tubine i hown in Fig Note that the C-haped oto blade i fomally called a 'topokien'. Guy wie C-haped oto '"//////////* Fig. 2.1 Vetical axi wind tubine 7

19 The pimay aeodynamic advantage of the vetical axi Daieu machine i that the tubine can eceive the wind fom any diection without the need of a yaw mechanim to continuouly oient the blade towad the wind diection. The othe advantage i that it vetical dive haft implifie the intallation of geabox and electical geneato on the gound, making the tuctue much imple. On the diadvantage ide, it nomally equie guy wie attached to the top fo uppot. Thi could limit it application, paticulaly fo offhoe ite. Wind peed ae vey low cloe to gound level, o although it might ave the need fo a towe, the wind peed will be vey low on the lowe pat of the oto. Oveall, the vetical axi machine ha not been widely ued becaue it output powe cannot be eaily contolled in high wind imply by changing the pitch. Alo Daieu wind tubine ae not elf-tating; howeve taight-bladed vetical axi wind tubine with vaiable-pitch blade ae able to ovecome thi poblem Hoizontal axi wind tubine Hoizontal axi wind tubine ae thoe machine in which the axi of otation i paallel to the diection of the wind. At peent mot wind tubine ae of the hoizontal axi type. Depending on the poition of the blade wind tubine ae claified into upwind machine and down wind machine a hown in Fig Mot of the hoizontal axi wind tubine ae of the upwind machine type. In thi tudy only the upwind machine deign i conideed. Wind tubine fo electic geneation application ae in geneal of thee blade, two blade o a ingle blade. The ingle blade wind tubine conit of one blade and a counteweight. The thee blade wind tubine ha 5% moe enegy captue than the two blade and in tun the two blade ha 1% moe enegy captue than the ingle blade. Thee figue ae valid fo a given et of tubine paamete and might not be univeally applicable. Fig. 2.2 Hoizontal axi wind tubine (a) upwind machine (b) downwind machine 8

20 The thee blade wind tubine ha geate dynamic tability in fee yaw than two blade, minimizing the vibation aociated with nomal opeation, eulting in longe life of all component. 2.3 POWER EXTRACTED FROM WIND Ai ha a ma. A wind i the movement of ai, wind ha a kinetic enegy. To convet thi kinetic enegy of the wind to electical enegy, in a wind enegy conveion ytem, the wind tubine captue the kinetic enegy of the wind and dive the oto of an electical geneato. The kinetic enegy (KE) in wind i given by = 1 2 (2.1) Wheem- i the ma of ai in Kg, V-i the peed of ai in m/. The powe in wind i calculated a the flux of kinetic enegy pe unit aea in a given time, and can be witten a = = = mv (2.2) whee m i the ma flow ate of ai pe econd, in kg/, and it can be expee in tem of the denity of ai ( in kg/m ) and ai volume flow ate pe econd (Q in m /) a given below.. m = ρ Q = ρav (2.3) WheeA-i the aea wept by the blade of the wind tubine, in m 2. Subtituting equation (2.3) in (2.2), we get P= AV (2.4) 9

21 Then the atio of wind powe extacted by the wind tubine to the total wind powe i the dimenionle powe coefficient Cp,which will alo effect the powe extacted fom wind. So the equation can be witten a P= AV C (2.5) WheeDi the weep diamete of the wind tubine. P= D V C (2.6) Thi i the total wind powe enteing the wind tubine. Thi calculation of powe developed fom a wind tubine i an idealized one-dimenional analyi whee the flow velocity i aumed to be unifom aco the oto blade, the ai i incompeible and thee i no tubulence whee flow i in vicid (having zeo vicoity). The volume of ai enteing the wind tubine hould be equal to the volume of ai leaving the wind tubine becaue thee i no toage of ai in the wind tubine. A a eult volume flow ate pe econd, Q, emain contant, which mean the poduct of A and Vemain contant. Hence when the wind leave the wind tubine, it peed deceae and expand to cove moe aea. The coefficient of powe of a wind tubine i a meauement of how efficiently the wind tubine convet the enegy in the wind into electicity.the coefficient of powe at a given wind peed can be obtained by dividing the electicity poduced by the total enegy available in the wind at that peed. The maximum value of powe coefficient C p give the maximum powe abobed by the wind tubine. In pactical deign, the maximum achievable C p i below.5 fo high peed, two blade wind tubine, and between.2 and.4 fo low peed tubine with moe blade. 1

22 Fig. 2.3 Detail of a wind tubine diven powe geneation ytem 2.4 TORQUE DEVELOPED BY A WIND TURBINE The toque in a wind tubine i poduced due to the foce ceated a a eult of peue diffeence on the two ide of each blade of the wind tubine. Fom fluid mechanic it i known that the peue in fat moving ai i le than in tationay o low moving ai. Thi pinciple help to poduce foce in an aeo plane o in a wind tubine. On a wind tubine oto the blade ae at ome angle to the plane of otation. At low haft peed, the angle of incidence on a blade element at ome adiu fom the hub i lage, the blade ae talled and only a mall amount of diving foce will be ceated. A a eult malltoque will be poduced at low haft peed. A the haft peed inceae the velocity 11

23 of the wind hitting the blade element inceae, becaue of the additional component of wind due to the blade' otational peed. In addition, the angle of incidence deceae. If thi angle i below the blade tall angle, lift inceae and dag deceae, eulting in highe toque. A the haft peed inceae futhe, the angle of incidence on the blade element deceae towad zeo a the fee wind peed become inignificant elative to the blade' own velocity. Since lift geneated by a blade i popotional to the angle of incidence below tall, the toque educe towad zeo at vey high haft peed. Fo a hoizontal axi wind tubine, opeating at fixed pitch angle, the toque developed by the wind tubine, T, can be expeed a P T = (2.7) ω Whee ω - angula velocity of the wind tubine, ad/. Wind Tubine Toque (Nm) m/ 1 m/ 12 m/ 11 m/ Tubine Speed (ad/ec) Fig. 2.4 Wind Tubine output toque a a function of tubine Speed 2.5 TIP-SPEED RATIO A tip peed atio TSR i imply the ate at which the end of the blade of the wind tubine tun (tangential peed) in compaion to how fat the wind i blowing. The tip peed atio TSR i expeed a: V ωt TSR = m = (2.8) V V ω ω 12

24 Whee V tn - tangential peed of the blade at the tip ω T - angula velocity of the wind tubine - adiu of the wind tubine V w - unditubed wind peed in the ite. The tip peed atio dictate the opeating condition of a tubine a it take into account the wind ceated by the otation of the oto blade. A typical powe coefficient C p veu tip peed atio TSR i given in Fig The tip peed atio how tangential peed at which the oto blade i otating compaed with the unditubed wind peed. A the wind peed change, the tip peed atio and the powe coefficient will vay. The powe coefficient chaacteitic ha ingle maximum at a pecific value of tip peed atio. Theefoe if the wind tubine i opeating at contant peed then the powe coefficient will be maximum only at one wind peed..6 Powe Coefficient,CP Tip Speed atio Fig.2.5.Powe Coefficient (v.) Tip Speed Ratio Cuve Uually, wind tubine ae deigned to tat unning at wind peed omewhee aound 4 to 5 m/. Thi i called the cut in wind peed. The wind tubine will be pogammed to top at high wind peed of 25 m/, in ode to avoid damaging the tubine. The top wind peed i called the cut out wind peed. 2.6 POWER CONTROL IN WIND TURBINES The output powe of a wind tubine i a function of the wind peed. The detemination of the ange of wind peed at which the wind tubine i equied to opeate depend on the pobability of wind peed obtained fom wind tatitic fo the ite whee the wind tubine i 13

25 to be located. Thi hitogam i deived fom long tem wind data coveing eveal yea. The hitogam indicate the pobability, o the faction of time, whee the wind peed i within the inteval given by the width of the column. In a wind powe ytem typically the wind tubine tat opeating (cut in peed) when the wind peed exceed 4-5m/, and i hut off at peed exceeding 25 to 3m/. In between, it can opeate in the optimum contant C p egion, the peed-limited egion o the powe limited egion. Thi deign choice wa made in ode to limit the tength and theefoe the weight and cot of the component of the wind tubine. Ove the yea ome enegy will be lot becaue of thi opeating deciion A dicued in Section 2.3 the powe abobed by the wind tubine i popotional to the cube of the wind peed. Hence thee hould be a way of limiting the peak abobed powe. Wind tubine ae theefoe geneally deigned o that they yield maximum output at wind peed aound 15 mete pe econd. In cae of tonge wind it i neceay to wate pat of the exce enegy of the wind in ode to avoid damaging the wind tubine. All wind tubine ae theefoe deigned with ome ot of powe contol to potect the machine. Thee ae diffeent way of doing thi afely on moden wind tubine Pitch contol In pitch contolled wind tubine the powe eno ene the output powe of the tubine. When the output powe goe above the maximum ating of the machine, the output powe eno end a ignal to the blade pitch mechanim which immediately pitche (tun) the oto blade lightly out of the wind. Conveely, the blade ae tuned back into the wind wheneve the wind peed dop again. On a pitch contolled wind tubine, in ode to keep the oto blade at the optimum angle and maximize output fo all wind peed, the pitch contolle will geneally pitch the blade by a mall angle evey time the wind change. The pitch mechanim i uually opeated uing hydaulic Yaw contol Yaw contol i a mechanim of yawing o tilting the plane of otation out of the wind diection when the wind peed exceed the deign limit. In thi way the effective flow co ection of the oto i educed and the flow incident on each blade conideably modified. 14

26 2.6.3 Stall contol Unde nomal opeating condition, a talled oto blade i unacceptable. Thi i becaue the powe abobed by the wind tubine will deceae, even to the point whee no powe i abobed. Howeve, duing high wind peed, the tall condition can be ued to potect the wind tubine. The tall chaacteitic can be deigned in to the oto blade o that when a cetain wind peed i exceeded, the powe abobed will fall to zeo, hence potecting the equipment fom exceeding it mechanical and electical ating. In tall contolled wind tubine the angle of the oto blade i fixed. The co ectional aea of the oto blade ha been aeodynamically deigned to enue that the moment the wind peed become too high, it ceate tubulence on the ide of the oto blade which i not facing the wind. The tall pevent the ceation of a tangential foce which pull the oto blade to otate. The oto blade ha been deigned with a light twit along it length, fom it bae to the tip, which help to enue that the wind tubine tall gadually, athe than abuptly, when the wind peed eache it citical value. The main advantage of tall contol i that it avoid moving pat in the oto blade itelf, and a complex contol ytem. Howeve, tall contol epeent a vey complex aeodynamic deign poblem, and elated deign challenge in the tuctual dynamic of the whole wind tubine, e.g. to avoid tall-induced vibation. Aound two thid of the wind tubine cuently being intalled in the wold ae tall contolled machine. 2.7 Summay The geneal definition of wind and the ouce of wind have been peented in thi chapte. The analyi of powe abobed by a wind tubine i baed on the hoizontal axi wind tubine. The mechanim of poduction of foce fom wind that caue the oto blade to otate in a plane pependicula to the geneal wind diection at the ite ha been dicued in detail. The impotance of having twited oto blade along the length fom the bae to the tip i given. The vaiation of the toque poduced by the wind tubine with epect to the oto angula peed ha been peented. Powe abobed by a wind tubine i popotional to the cube of the wind peed. Wind tubine ae deigned to yield maximum output powe at a given wind peed. Diffeent way of powe contol to potect the machine have been peented. 15

27 CHAPTER 3 AXES TRANSFORMATION 16

28 3.1 INTRODUCTION Mathematical tanfomation ae tool which make complex ytem imple to analyze and olution eay to find. In electical machine analyi a thee-phae axe to two-phae axe tanfomation i applied to poduce imple expeion that povide moe inight into the inteaction of the diffeent paamete. The diffeent tanfomation tudied in the pat ae given in [1] 3.2 GENERAL CHANGE OF VARIABLES IN TRANSFORMATION A ymmetical thee phae machine i conideed with theeaxe at 12 degee apat a hown in fig.2.the thee axe ae epeenting the eal thee phae upply ytem. Howeve, the two axe ae fictitiou axe epeenting two fictitiou phae pependicula, diplaced by 9 o, to each othe. The tanfomation of thee-axe to two-axe can be done in uch a way that the two-axe ae in a tationay efeence fame, o in otating efeence fame. The tanfomation actually achieve a change of vaiable, ceating the new efeence fame. Tanfomation into a otating efeence fame i moe geneal and can include the tanfomation to a tationay efeence fame. If peed of the otation of the efeence fame i zeo it become a tationay efeence fame. If the efeence fame i otating at the ame angula peed a the excitation fequency, when the vaiable ae tanfomed into thi otating efeence fame, they will appea a a contant value intead of time-vaying value Tanfomation into a tationay efeence fame Hee the aumption taken i that the thee-axe and the two-axe ae in a tationay efeence fame. It can be ephaed a a tanfomation between abc and tationay dq axe. To viualize the tanfomation fom thee-axe to two-axe, the tigonometic elationhip between thee-axe and two-axe i given below. 17

29 Fig. 3.1 Thee-axe and two-axe in the tationay efeence fame In the above diagam, Fig. 3.1, f can epeent voltage, cuent, flux linkage, o electic chage. The ubcipt indicate the vaiable, paamete, and tanfomation aociated with tationay cicuit. The angula diplacement θ how the diplacement of the two-axe, dq-axe, fom the thee-axe, abc-axe. f q and f d vaiable ae diected along path othogonal to each othe. f a, f b, and fc may be conideed a vaiable diected along tationay path each diplaced by 12 electical degee. A change of vaiable which fomulate a -phae tanfomation of the thee vaiable of tationay cicuit element to an abitay efeence fame can be expeed a [1]: = co co co in in in (3.1) It i impotant to note that the zeo-equence vaiable ae not aociated with the abitay efeence fame. Intead, the zeo-equence vaiable ae elated aithmetically to the abc vaiable, independent of θ. 18

30 The invee of Equation (3.1), which can be deived diectly fom the elationhip given in Fig. 3.1, i co in 1 = co in 1 co in 1 (3.2) In Fig. 3.1, if the q-axi i aligned with the a-axi, i.e. θ=, Equation (3.1) will be witten a: = 1 (3.3) and Equation (3.2) will be implified to: 1 1 = 1 1 (3.4) In Equation (3.3) and (3.4) the magnitude of the phae quantitie, voltage and cuent, in the thee (abc) axe and two (dq) axe emain the ame. Thi tanfomation i baed on the aumption that the numbe of tun of the winding in each phae of the thee axe and the two axe ae the ame. Hee the advantage i the peak value of phae voltage and phae cuent befoe and afte tanfomation emain the ame. 19

31 3.2.2 Tanfomation into a otating efeence fame The otating efeence fame can have any peed of otation depending on the choice of the ue. Selecting the excitation fequency a the peed of the otating efeence fame give the advantage that the tanfomed vaiable, which had intantaneou value, appea a contant (DC) value. In othe wod, an obeve moving along at that ame peed will ee the pace vecto a a contant patial ditibution, unlike the time-vaying value in the tationay abc axe. Thi efeence fame move at the ame peed a the obeve. Since we ae dealing with two- baicpace vecto, dimenional vaiable, the otating efeence can be any two independent which fo convenience anothe pai of othogonal dq axe will be ued. The zeo-equence component emain the ame a befoe. Fig. 3.3 how the abc to otating dq tanfomation in two tep, i.e., fit tanfoming to tationay dq axe and then to otating dq axe. (a) (b) Fig. 3.2 Step of the abc to otating dq axe tanfomation (a) abc to tationay dq axe b) tationay d -q to otating d e -q e axe The equation fo the abc to tationay dq-axe tanfomation i given in Equation (3.5). Uing geomety, it can be hown that the elation between the tationay d -q axe and otating d e -q e axe i expeed a: 2

32 in =co in co (3.5) The angle, θ, i the angle between the q-axi of the otating and tationay d -q axe. 6 i a function of the angula peed,, of the otating d e -q e axe and the initial value, that i = (3.6) If the angula peed of the otating efeence fame i the ame a the excitation fequency then the tanfomed vaiable in the otating efeence fame will appea contant (DC). The thee phae voltage and cuent ae obtained by applying d-q to a-b-c tanfomation equation a above explained 1 fa 1 3 fq f b = 2 2 f d f c (3.7) wheef a,f b and f c ae thee phae voltage o cuent quantitie and f q and f d ae the two-phae voltage o cuent quantitie. 3.3SUMMARY The thee-axe to two-axe tanfomation peented in thi chapte i applicable fo any balanced thee-phae ytem. It ha been dicued that the thee-axe to two-axe tanfomation implifie the calculation of m cuent, m voltage, active powe and powe facto in a theephae ytem. Only one et of meauement taken at a ingle intant of time i equied when uing the method decibed to obtain m cuent, m voltage, active powe and powe facto. And fom meauement taken at two conecutive intant in time the fequency of the theephae AC powe upply can be evaluated. 21

33 CHAPTER 4 THE SEIG SYSTEM 22

34 4.1 INTRODUCTION: A dicued in the peviou chapte, enewable enegy i the key to ou low cabon enegy futue. The ue of an induction machine a a geneato i becoming moe and moe popula fo enewable enegy application [8], [9]. Squiel cage induction geneato with excitation capacito (known a SEIG) ae popula in iolated nonconventional enegy ytem [17], [22]. The main limitation of the SEIG ytem i the poo voltage and fequency egulation when upplying vaiable load connected to the tato teminal. Howeve, the development of tatic powe convete ha facilitated the contol of the output voltage and fequency of the induction geneato. Thi chapte peent a liteatue eview of the development, the elf-excitation phenomena, the pefomance and the opeational poblem of the SEIG ytem. 4.2 SEIG SYSTEM CONFIGURATION The SEIG ytem i compoed of fou main item: the pime move, the induction machine, the load and the elf-excitation capacito bank. The geneal layout of the SEIG ytem i hown infigue 4.1. Figue 4.1 Schematic diagam of a tandalone elf-excited induction geneato. 23

35 The eal powe equied by the load i upplied by the induction geneato by extacting powe fom the pime move (tubine). When the peed of the tubine i not egulated, both the peed and haft toque vay with vaiation in the powe demanded by the load. The elf-excitation capacito connected at the tato teminal of the induction machine mut poduce ufficient eactive powe to upply the need of the load and the induction geneato. A quiel cage induction geneato (SCIG) i moe attactive than a conventional ynchonou geneato in thi type of application becaue of it low unit cot, abence of DC excitation ouce, buhle cage oto contuction and lowe maintenance equiement [1]. A uitably ized thee-phae capacito bank connected at the geneato teminal i ued a vaiable lagging VA ouce to meet the excitation demand of the cage machine and the load. The machine opeated in thi mode i known a a Self-excited Induction Geneato (SEIG). Howeve, the main dawback of the tandalone SEIG i it poo voltage and fequency egulation unde vaiable load. A change in the load impedance diectly affect the excitation of the machine becaue the eactive powe of the excitation capacito i haed by both the machine and the load. Theefoe, the geneating voltage dop when the impedance of the load i inceaed eulting in poo voltage egulation. Poo fequency egulation occu (an inceae in the lip of the induction machine) when the load i inceaed. 4.3THE SELF-EXCITATION PHENOMENON The elf-excitation phenomenon of an induction machine i till unde conideable attention although it i known fo moe than a half centuy [9],[11]. When a tandalone induction machine i diven by a mechanical pime move, the eidual magnetim in the oto of the machine induce an EMF in the tato winding at a fequency popotional to the oto peed. Thi EMF i applied to the capacito connected to the tato teminal and caue eactive cuent to flow in the tato winding. Hence a magnetizing flux in the machine i etablihed. The final value of the tato voltage i limited by the magnetic atuation within the machine. The induction machine i then capable of opeating a a geneato in iolated location without a gid upply. 24

36 Once the machine i elf-excited and loaded, the magnitude of the teady-tate voltage geneated by the SEIG i detemined by the nonlineaity of the magnetizing cuve, the value of the elfexcitation capacitance, peed, machine paamete and teminal load. A the load and peed of the SEIG change, the demand fo lagging VA to maintain a contant AC voltage aco the machine teminal alo change SEIG SYSTEM PERFORMANCE The pefomance chaacteitic of the SEIG ytem depend mainly on the following: a. The paamete of the induction machine b. The machine opeating voltage, ated powe, powe facto, oto peed and opeating tempeatue and the induction machine paamete diectly affect the pefomance of the SEIG ytem. c. The Self-excitation poce d. The connection of a capacito bank aco the induction machine tato teminal i neceay in the cae of tandalone opeation of the ytem. The capacito connection cheme (delta o ta) and the ue of fixed o contolled elf-excitation capacito have a diect impact on the pefomance of a SEIG ytem. e. Load paamete f. The powe facto, tating/maximum toque and cuent, geneated hamonic and load type alo affect the pefomance of the SEIG ytem diectly. g. Type of pime move Whethe the pimay ouce i hydo, wind bioma o combination, the pefomance of the SEIG ytem i affected OPERATIONAL PROBLEMS OF THE SEIG SYSTEM The main opeational poblem of the SEIG ytem i it poo voltage and fequency egulation unde vaying load condition [11]. A change in the load impedance diectly affect the machine 25

37 excitation. Thi i becaue the eactive powe of the excitation capacito i haed by both the induction machine and the load impedance. Theefoe, the geneato voltage dop when the load impedance i inceaed eulting in poo voltage egulation. On the othe hand, the lip of the induction geneato inceae with inceaing load, eulting in a load dependent fequency, even if the peed of the pime move emain contant. 4.4 SUMMARY An oveview of the elf-excitation phenomenon wa peented in thi chapte. The pefomance chaacteitic and opeational poblem of SEIG ytem wee alo given. The pime move, the induction machine, the load and the elf-excitation capacito ae the fou main item compiing the SEIG ytem.howeve, thi thei i focued on tudying and analyzing the teady-tate nonlinea behavio of the SEIG ytem a a nonlinea dynamic ytem. Poo voltage and fequency egulation ae two majo dawback of the SEIG ytem unde vaiable load condition. 26

38 CHAPTER 5 MODELING OF STAND- ALONE WIND-DRIVEN SEIG SYSTEM 27

39 5.1 MODELLING OF WIND TURBINE The mechanical ytem conit of a wind tubine along with a gea box. Eq. 5.1 epeent the aeodynamic powe geneated by wind tubine, whee the aeodynamic powe i expeed a a function of the pecific denity (ρ) of the ai in kg/m 3, the wept aea of the blade (A) in m 2, pefomance co-efficient of the tubine (C P ) and the wind velocity (ν ω ) in m/[13]. 3.5 w P = ρac P v (5.1) Fo diffeent value of wind peed a typical wind tubine peed chaacteitic i hown in Fig.2.4 The cuve between powe coefficient (C P ) and tip peed atio (λ) at zeo degee pitch angle (β) i hown in Fig.2.5, which how that C P eache a maximum value of.48 fo a maximum tip peed atio of 8.1 fo any value of wind peed. Tip peed atio of the wind tubine can be calculated uing equation (2.5), whee ω T i the otational peed of wind tubine, R i the adiu of wind tubine, ω T R i the linea peed at the tip of the blade. w R v T λ = (5.2) w The polynomial elation between epeented by equation 5.3. C p and λ at paticula pitch angle fo conideed wind tubine [14] i C5 C2 λ i CP ( λ, β ) = C1 C3β C4 e + C6λ λ (5.3) i whee = (5.4) λ i ( λ +.8β ) ( β 3 + 1) wheec 1 =.5176, C 2 =116, C 3 =.4, C 4 =5, C 5 =21 and C 6 =

40 5.2 MODELLING OF SELF EXCITED INDUCTION GENERATOR Fo the development of an induction machine model in tationay fame, the d-q abitayefeence fame model of machine [12] i tanfomed into tationay efeence fame. Fig5.1 how the chematic d-q axe diagam of SEIG. Capacito ae connected aco the tato teminal to make the machine elf-excited; the efeence diection of cuent and voltage ae indicated in Fig 5.2 (a) and (b). Uing d-q component of tato cuent (i d and i q ) and oto cuent (i d and i q ) a tate vaiable [2], the above diffeential equation ae deived fom the equivalent cicuit hown in Fig Fig. 5.1 Schematic d-q axe diagam of SEIG In tationay efeence fame the dynamic machine model can be deived by ubtituting w e = in ynchonouly otating efeence fame d-q model equation. The d-q axe equivalent cicuit of a (SEIG) upplying an inductive load i hown in Fig

41 Fig.5.2 d-q model of induction machine in the tationay efeence fame (a) d-axi (b) q-axi Fom above cicuit by applying KVL we can get the voltage equation a follow v v q d q = R i d = R i q dλ + dt d dλ + dt = R iq q dλ + dt w λ q = R i d dλ + dt d w λ d = R i q dλ + dt q w λ Whee V q = V d = The flux linkage expeion in tem of the cuent can be witten fom Figue q λ q = L i + L q m i q 3

42 λ q = L i + L q m i q λ d = L i + L d m i d λ d = L i + L d m i d di q dt = did = dt di 1 ( ) [ ] 2 L iq w Lmid + Lm iq w LmL id + Lv 2 q L L L m 1 ( ) [ ] 2 w Lmi q L S id + w LmL iq + Lm id + Lv 2 d L L L m 1 ( ) [ L ] ms iq + w LmLi d Li q + w L Li d Lmv q L L L q = 2 m dt did dt = 1 2 ( ) [ w ] LmL iq + Lm Sid w L Li q L id + Lmv d L L L m (5.5) (5.6) (5.7) (5.8) Whee L + = Ll Lm, L = Ll + Lm = L i + L i λ q q m q, λ d = L id + Lmid The electomagnetic toque can be computed a a function of q and d axe tato and oto cuent and epeented in equation (5.9). T e 3 P = L 2 2 m [ i i i i ] q d d q (5.9) The ubcipt q and dae fo quadatue and diect axe; ubcipt and ae fo tato and oto vaiable; l fo leakage component; v and i intantaneou voltage and cuent; λ flux linkage; i m magnetizing cuent; L m magnetizing inductance; eitance; L inductance; P numbe of pole; ω electical oto peed; and T e electomagnetic toque. The magnetization chaacteitic of the SEIG i nonlinea. The magnetizing inductance L m i not a contant but a function depend on the intantaneou value of magnetizing cuent i m given by L m =f (i m ). 31

43 Duing imulation, in each tep, the magnetizing inductance L m i updated a a function of the magnetizing cuent i m. The magnetizing cuent i epeented by equation (5.1). ( i + i ) + ( i i ) 2 2 m = d d q q (5.1) i + The magnetizing inductance L m i calculated fom the magnetizing chaacteitic fouth ode polynomial fo the tet machine i m. The 4 th ode polynomial i aived at, by applying cuve fit technique to the elationhip between L m and i m, obtained by pefoming ynchonou peed tet on the tet induction machine. Toque balance equation i epeented by equation (5.11). 2 dw Thaft = Te + J (5.11) P dt The toque balance equation given in (5.11) may be expeed in peed deivative fom a [9] dw dt P J ( T T ) = e haft 2 (5.12) 5.3 MODELLING OF EXCITATION CAPACITOR The excitation ytemintoduce the following tate equation 5.13 and 5.14 uing d-q component of tato voltage ( v d & v q ) a tate vaiable, fom the cicuit hown in Fig 3 (b). i = i + i dc qc ld i = i + i lq cd cq dv dt ld idc = C ild C (5.13) dv dt lq iqc = C ilq C (5.14) 32

44 5.4 MODELLING OF LOAD IMPEDANCE An induction geneato i elf-excited by poviding the magnetizing eactive powe by a capacito bank a hown in Fig 1 and the d and q axe cuent equation fo the balanced eitive load can be given by equation i i Rq Rd v = R q L v = R And fo the load conideed i R-L load ( =5 Ω and = 5mH). The load equation of the induction geneatoae epeented in the ame efeence fame ae given below. d L v = Ri ld ld + di dt ld L i ld 1 v L R i L = ld ld (5.15) di vlq = Rilq + dt lq L i lq 1 v L R i L = lq lq (5.16) If the load i capacitive in natue, then the capacito value will be added to the excitation capacito value. A claical matix fomulation uing d-q axe model i ued to epeent the dynamic of conventional induction machine opeating a a geneato [16, 17, 18, and 19]. Uing thi matix epeentation, we can obtain the intantaneou voltage and cuent duing the elf-excitation poce, a well a duing load vaiation. 33

45 34 + = q d q d m m m m lq ld lq ld q d q d m m m m m m m m m m m m lq ld lq ld q d q d v v v v L L L L L L L L i i v v i i i i LK R LK LK R LK CK CK CK CK L L R w L L R L L w L L w L L L R L w L R L L R L L w L L R w L L L w L R L w L L R dt di dt di dt dv dt dv dt di dt di dt di dt di Whee id, i d, i q, i q ae epectively the tato and oto cuent in diect and quadatue axi and v d and v q ae the initial diect axi and quadatue axi applied voltage and ( ) m L L L K = 2 1. Combining the above expeion, the electical tanient model in tem of voltage and cuent can be given in matix fom a ( ) ( ) = dt dl L w dt dlm L w L w dt dl L w dt dlm dt dlm RC dt LR d dt dl R dt dl R dt dlm RC dt LR d dt dl R dt dl R v v v v m m q d q d

46 Fo ingly fed machine, uch a a cage moto in tationay fame, v q = v d = and w e = in the above matix. 5.5 DEVELOPMENT OF WIND DRIVEN SEIG DYNAMIC MODEL IN MATLAB/SIMULINK The wind tubine act a pime-move fo the induction machine and both ae coupled though a gea box a hown in hown in Fig. 5.3 and dynamic model of Wind Diven SEIG i implemented in Simulink envionment by taking equation and the flow chat in Fig.5.3. Initiation of elf-excitation i baed on eidual magnetim in the oto cicuit and voltage build up with the uppot of eactive cuent upplied by the capacito bank. Load i connected to the Wind diven SEIG afte the voltage i developed to a teady tate value. Fig 5.3. Flow chat fo dynamic of Wind Tubine model 35

47 Simulation of the dynamic model of wind diven SEIG ha been caied out with the view to compute the intantaneou value of cuent and voltage of induction machine, the excitation ytem and the load. The developed dynamic model i imulated by uing the numeical integation technique Runge-kutta fouth ode method. Fo getting an accuate eult, tep length hould be a mall a poible but on the othe hand it will take moe time. In thi cae 5µ i conideed a a tep time. In cae of the SEIG the vaiation of magnetization inductance i the main facto in the dynamic of voltage build up and tabilization. Fom the ynchonou peed tet vaiation of magnetizing inductance L m i obtained with epect to i m.befoe imulation i un, it i neceay to povide initial value of the input tate of the q-d model of the induction geneato. The initial value of the cuent i "," i "," i " and i " ae aumed to be zeo. Fo " d q d the pupoe of elf-excitation, the eidual magnetim of the machine i taken a initial value of " v d " and v ". The imulation eult of wind diven SEIG in iolated mode ae dicued in the " q next ection. " q 5.6 SUMMARY The chapte peent the mathematical modeling equation fo diffeent paamete of wind tubine, elf-excited induction geneato, excitation capacito and load impedance.uing all thee d-q equation of machine a claical matix i fomulated which i ued to epeent the dynamic of conventional induction machine opeating a a geneato. By uing thee equation in Matlab/Simulink a wind diven elf-excited induction geneato can be implemented. Thi chapte alo explain the flow chat fo dynamic of Wind Tubine model. 36

48 CHAPTER6 RESULTS & DISCUSSION 37

49 6.1 SIMULATION RESULTS Specification of wind tubine and induction Machine taken fo the imulation i given in table. The magnetization cuve fo the above machine ae expeed in tem of L m (H) V i m (A) i given in table 3 and table 6. Table-1 (Wind tubine coupled with 22kW induction machine) Rated Powe (kw) 25 Diamete ( m) 12.8 No. of Blade 3 Cut-in wind Speed 3 m/ Cut-out wind peed 25 m/ Table-2(Induction machine 22 kw,3-phae,4 Pole ta connected,415 volt,5 hz) R (Ω) R (Ω) Xl (Ω) Xl (Ω) Lm (H) J (kg m 2) Table-3(L m vi m ) i m (A) L m (H) (i m -8) (i m -13) Table-4(Wind tubine coupled with 7.5 kw induction machine) Rated Powe (kw) 1 Diamete ( m) 8 No. of Blade 3 Rated wind Speed 1 m/ 38

50 Table-5 (Induction machine 7.5 kw,3-phae,4 pole ta-delta connected,415 volt,5 hz) R (Ω) R (Ω) Xl (Ω) Xl (Ω) Lm (H) J (kg m 2) Table-6(L m vi m ) I m (A) L m (H) e-5I m I m The tanient behavio of 22 kw, 7.5 kw SEIG coupled with wind tubine, pecification ae given in the above table having balanced delta-connected excitation capacito aco the teminal of SEIG ha been tudied. The tanient behavio of the wind diven SEIG unde the following condition ha been obeved. 1. Self-excitation poce 2. Inetion of load 3. Lo of excitation due to heavy-load 4. Inetion of excitation capacito 5. Change in wind velocity 6.1.1Self-excitation Poce The fixed excitation capacitance i elected a 152 µf, fo the 22 kw induction machine data i given in table 1 taken fom [6]. The SEIG diven by wind tubine with wind velocity of 12.6 m/ at no load and the imulation eult ae hown in Fig It i obeved that the eidual magnetim taken in tem of V d andv q a 1 volt fo the imulation induce a voltage aco the elf-exciting capacito and poduce a capacitive cuent o a lagging magnetizing cuent in the tato winding and eult a highe voltage. Thi pocedue goe on until the atuation of the 39

51 magnetic field occu a obeved in the imulation eult hown in Fig. 6.2 and 6.3. It i alo obeved that fo SEIG oto peed of 1725.p.m hown in Fig. 6.1, the voltage and cuent wavefom of SEIG each the teady tate condition within 7.38 ec following the voltage build up poce. The teady tate magnitude of the peak SEIG teminal voltage i 337 volt(m236 ) and tato cuent i amp at no load hown in Fig. 6.4 and Fig. 6.5 Fig.6.1 SEIG Roto peed Fig. 6.2 Magnetizing cuent Fig.6.3Magnetizing Inductance Fig.6.4 Stato teminal Voltage 4

52 Fig.6.5 Stato cuent wave fom Inetion of Load Fig ae the imulation eult of 7.5 kw induction machine at contant wind peed of 11m/ fo R-L load having p.f.8 applied at t=5 econd. It i obeved that teady tate peak voltage i 332 volt at no load, educe to193 volt and peed educe fom 172.p.m to 175.p.m hown in Fig.6.6 and 6.8. When the SEIG i opeating at no-load, the load cuent i zeo, the load cuent eache a teady-tate value of 2.96 ampee (peak amplitude) hown in Fig Loading deceae the magnetizing cuent I m hown in Fig.6.1 which eult in the educed flux. Reduced flux implie educed voltage Lo of Excitation due to heavy-load The SEIG which i initially opeated unde teady tate condition having peak value of voltage 332 volt and R-L load i applied at t=5eond having p.f.8, voltage i educed and eached a teady tate voltage of 193 volt. At t=8 econd an exta load i applied, the SEIG line voltage collape i a monotonou decay of the voltage to zeo hown in Fig Once the voltage collape occu, the e-excitation of the geneato become difficult. Thu it how the poo oveloading capability of the SEIG. Theefoe the load connected to the geneato hould neve 41

53 exceed beyond the maximum load the geneato can delive unde teady tate condition. But it may be mentioned hee that the momentay exce tato cuent can opeate potective elay to iolate the oveload condition at the geneato teminal to pevent voltage collape. Fig.6.6 SEIG Stato teminal Voltage Fig.6.7Peak SEIG teminak voltage/phae Fig.6.8SEIG oto peed vaiation with load 42

54 Fig. 6.9SEIGtato cuent wavefom Inetion of Excitation Capacito The SEIG i initially opeated unde teady tate condition with thee-phae balanced deltaconnected capacito bank of 9 µf/phae connected aco it tato teminal while eitive load of 8 Ω i connected at t=5 econd, the teady tate voltage i educed fom 332 volt to 35 volt. The inceae in load cuent hould be compenated eithe by inceaing the enegy input (dive toque) theeby inceaing the oto peed o by an inceae in the eactive powe to the geneato. At t=7 excitation capacito of 1 µf/phae i added to the exiting value. The coeponding imulation eult ae hown in Fig It i obeved fom Fig that the peak magnitude of tato voltage inceae to 316 volt with the addition of excitation capacito value. Fig.6.16 and 6.17 epeent the eal powe vaiation and eactive powe vaiation due to addition of load at t=5 ec and inetion of excitation capacito at t= 7 ec. 43

55 Fig.6.1 Vaiation of I µ with load Fig.6.11 Load cuent vaiation with load Fig.6.12 Lo of excitation 44

56 Fig.6.13 Peak SEIG teminal voltage/phae Fig.6.14 Roto peed vaation with load and addition of capacito Fig.6.15 I µ Vaiation Fig.6.16 Real powe vaiation 45

57 Fig.6.17 Reactive powe vaiation Fig.6.18 Step change in wind velocity Fig.6.19 Stato voltage vaiation with tep change in wind velocity Step change in wind velocity Simulation eult with tep change in wind velocity ae hown in Fig , a the wind velocity inceae fom 1 m/ to 12 m/ at t = 4econd, the mechanical input fom the wind 46

58 tubine inceae and thi eult in the inceaed oto peed cauing an inceae in the tato teminal voltage. When wind velocity deceae fom 12 m/ to 9 m/ at t = 5 econd, oto peed deceae and hence deceae the tato teminal voltage of SEIG. Fig.6.2 Roto peed vaiation with Step change in wind velocity Fig.6.21I m Vaiation 6.2 EXPERIMENTAL RESULTS Conducted the open loop expeiment with the available 5 hp induction machine in the machine laboatoy. The expeimental et up i a hown in below figue. Lamp load i alo connected to the machine. Initially capacito ae chaged fo few minute by giving thee phae upply to povide eactive powe to the induction machine when it i opeating a induction geneato. Now by giving DC upply to the DC hunt moto which act like pime move fo the induction machine. By adjuting the heotat connected in amatue and field cicuit of DC moto the induction machine i made to un above ynchonou peed Now the machine act a induction geneato by taking eactive powe fom the capacito connected aco tato of the machine. The geneated wavefom ae obeved in the CRO. 47

59 Fig.6.22 Expeimental etup We can obeve the buildup of voltage fom zeo to 415v and afte ome time due to atuation voltage getting ettled at 415v. Fig.6.23 Build up of Line Voltage 48

60 Fig.6.24 Settled voltage By applying load Hea we can alo obeved the deceae in geneated voltage when load i applied on the induction machine. Fig.6.25 Deceae in voltage by eleaing Load Fig.6.26 Reduced voltage afte eleaing Load 49

61 By eleaing the load Hee we can obeve the inceae in voltage when the load on the induction machine i eleaed. Fig.6.27 Inceae in voltage by eleaing Load 5