Inter national J our nal of Electrical and Computer Engineering (IJECE) V ol. 9, No. 3, June 2018, pp. 1531 1540 ISSN: 2088-8708, DOI: 10.11591/ijece.v9i3.pp1531-1540 r 1531 Dir ect and indir ect v ector contr ol of a doubly fed induction generator based in a wind ener gy con v ersion system Manale Bouderbala 1 , Badr e Bossoufi 2 , Ahmed Lagrioui 3 , Mohammed T aoussi 4 , Hala Alami Ar oussi 5 , Y asmine Ihedrane 6 1,2,5 Laboratory of Electrical Engineering and Maintenance, Higher School of T echnology , Oujda, Morocco 3 Department of Electrical and Computer Engineering The Higher National School of Arts and T rades, Moulay Ismail Uni v ersity Meknes, Morocco 2,4,6 LIST A Laboratory , F aculty of Sciences Dhar El Mahraz, Uni v ersity Sidi Mohammed Ben Abdellah Fez – Morocco Article Inf o Article history: Recei v ed Jun 4, 2018 Re vised No v 16, 2018 Accepted Des 15, 2018 K eyw ords: W ind po wer Doubly- fed induction generator (DFIG) Direct field oriented control (DFOC) Indirect field oriented control (IFOC) MPPT control ABSTRA CT In the recent years, the de v elopment and the e xploitation of rene w able ener gy kne w a great e v olution. Among these ener gy resources, the wind po wer represents an impor - tant potential for that the wind system has been the subject of se v eral researches. The purpose of this study is to impro v e the po wer e xtract ed from wind ener gy , taking into consideration the v ariation of wind speed which causes a problem in ener gy produc- tion . F or this purpose, we ha v e controlled the po wers whether it is ac ti v e or reacti v e deli v ered by the generator . This paper , presents essentially the modeling and control of doubly- fed induction generator (DF IG), which is connected to a v ariable speed wind turbine. Firstly , the model of the wind po wer system with the maximum po wer point tracking (MPPT) strate gy is sho wn. Then, the modeling of doubly- fed induction generator (DFIG) and its po wer control is presented. Finnaly , to ensure the att itude of these controls the simulations is presented in the Matlab/Simulink en vironment. Copyright c 2019 Insitute of Advanced Engineeering and Science . All rights r eserved. Corresponding A uthor: Bouderbala Manale, Electrical Engeneering and Maintenance Laboratory , Mohammed First Uni v ersity , Higher School of T echnologie Oujda, Morocco. Email: Bouderbala manale1718@ump.ac.ma 1. INTR ODUCTION F ollo wing the strong industrialisation, electric ener gy will al w ays reside an ener gy that humanity can not do without it. F ossil fuels ha v e long been used in the production of electrical ener gy , these fossil fuels are causing harmful damage to the en vironment. [1] T o meet the high demand of ener gy and at the same time k eep the en vironment safe, the majority of countries has opted for the use of rene w able ener gies. These ener gies are ine xhaustible, clean and do not create greenhouse g ases unlik e fossil fuels. [2][3] Among the rene w able ener gies, wind ener gy is e xperiencing a significant gro wth and is considered as a mature and economical technology[4]. Ho we v er , the problem is that this resource is characterized by v ariable wind speed [5]. F or this reason, we ha v e opted for the generator doubly fed induction, as well as other adv antages such as; reducing the sizing of the con v erters, and impro ving the quality of the ener gy produced. On the other hand, the control of this machine remains the most important and comple x phase.[6][7] In that w ay we will start our study by modeling the wind turbine. Then, the MPPT control which ensures an important role to e xtract the maximum of po wer . Thereaf ter , the modeling of the DFIG, and also the po wer control which is done by the v ector control. In terms of this l ater we ha v e tw o types: direct field oriented control(DFOC) and indirect oriented field control(IFOC). Finally , the results of the simulations will be presented in the en vironment Matlab/Simulink in order to conclude the most ef ficient and rob ust control also the impact of the MPPT control on the system . J ournal homepage: http://iaescor e .com/journals/inde x.php/IJECE Evaluation Warning : The document was created with Spire.PDF for Python.
1532 r ISSN: 2088-8708 2. MODELLING OF WIND TURBIN The wind turbine allo ws the transformation of kinetic ener gy i n t o mechanical ener gy and then into electrical ener gy through a generator . W ind po wer depends on the surf ace to be swept (S), wind speed (v) and air density ( ) . Based on the fluid mechanics equations we ha v e the follo wing equation [8][9]: P v = :S :V 3 2 (1) According to Betz’ s la w , a wind turbine can ne v er con v ert more than 16/27 (or %59 ) of the kinetic ener gy of the wind. Cp e xpresses the aerodynamic ef ficienc y of the wind turbine. It depends on the ratio ( ) , and the angle of orientation of the blades ( ) . The ratio ( ) and Cp are e xpressed by the follo wing relations [3]: = R : t V (2) C p ( ; ) = (0 : 5 0 : 0167 : ( 2)) : sin( : ( + 0 : 1) 18 : 5 0 : 3 : ( 2) ) 0 : 00184 : ( 3) : ( 2) (3) Where t is the speed of the turbine, R is the wind turbine radius. The aerodynamic po wer , which is con v erted by a wind turbine depends on the po wer coef fici ent Cp, the follo wing equation sho ws it [2][4]: P aer = C p ( ; ) :P v (4) The follo wing relationship describes the aerodynamic torque T aer = P aer t = C p ( ; ) : :S :V 3 2 : t (5) In order to adapt the slo w speed of the turbine to the speed of the generator , a multiplier is added, this latter is modelled by the follo wing equations [6]: C g = C t G (6) t = mec G (7) Where Cg is the generator torque, mec is the high speed of the generator , G: multiplier g ain From the fundamental equation of the dynamics we can determine the mechanical speed, ho we v er the mechanical torque is gi ving by [5][4]: J d mec dt = T mec = T g T em f : mec (8) Where T em is the electromagnetic torque, T mec is themechanical torque, f is the viscous friction torque, J is the total inertia. 3. MAXIMUM PO WER POINT TRA CKING CONTR OL The goal of the MPPT is to optimize the wind ener gy captured by follo wing the optimal speed. In order to reco v er as much ener gy as possible from the wind turbine, we must continuously adapt the mechanical speed of the DFIG to t he wind speed. Therefore, it is possible to estimate in real time the v alue of the wind speed . Then, the electromagnetic torque e xtracted from the MPPT control is applied to the DFIG to sure that the generator operates at its optimal speed. This diagram as sho wn in Figure 1 illustrates the wind turbine model with the MPPT control model [3][9]: IJECE, V ol. 9, No. 3, June 2018 : 1531 – 1540 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 r 1533 Figure 1. T urbine and MPPT model The estimated v alue of the wind speed is gi v en by: V est = R : t opt (9) The e xpression of the reference po wer becomes: P aer r ef = C p max ( ; ) : :S :V est 3 2 (10) The e xpression of the reference electromagnetic torque becomes: T em r ef = P aer r ef t = 1 2 :C p max ( ; ) : : :R 5 C p max 3 : t 2 (11) 4. MODELLING OF THE DFIG The stator of the machine is directly connected to the po wer grid, b ut the rotor is connected through the po wer electronics. The mathematical model of DFIG in the park referential (d-q) is gi v en by the follo wing equations [10][11][12][13]: V sd , V sq , sd , sq are respecti v ely the equations of the v oltages and stator flux in the d-q reference. V sd = R s :I sd + d sd dt sq :! s V sq = R s :I sq + d sq dt sd :! s sd = L s :I sd + M :I r d sq = L s :I sq + M :I r q (12) V r d , V r q , r d , r q are respecti v ely the equations of the v oltages and rotor flux in the d-q reference. V r d = R r :I r d + d r d dt r q :! r V r q = R r :I r q + d r q dt r d :! r r d = L r :I r d + M :I sd r q = L r :I r q + M :I sq (13) Rs,Rr: stator and rotor resistances. Ls,Lr: c yclic stator and rotor Inductances. M: mutual inductance. The frequenc y of the stator v oltage is being imposed by the grid, in the opposite the pulsation of the rotor currents is gi v en by: ! r = ! s ! w ith ! = p: (14) p: Number of pole pairs of the machine. ! s , ! r : Pulse of the stator and rotor electrical quantities respecti v ely . The Electromagnetic torque is e xpressed by: Dir ect and indir ect vector contr ol of ... (Manale Bouderbala) Evaluation Warning : The document was created with Spire.PDF for Python.
1534 r ISSN: 2088-8708 T em = p: M L s : ( sq :I r d sd :I r q ) (15) The Acti v e and reacti v e stator po wers are: P s = V sd :I sd + V sq :I sq Q s = V sq :I sd + V sd I sq (16) 5. FIELD ORIENTED CONTR OL V ector control is one of the most widely used techniques for controlling electrical machines. It is based on the f act that the machine is similar to a DC machine wit h separate e xcitation, this latter ensures a natural decoupling between currents and flux. [14][15] According to the equation (15) we see clearly the strong coupling between the flux es and the currents rotoric and statoric which generates a dif ficulty in the control of the DFigure The principle of v ector control is to orient the flux of the machine in one of the tw o ax es d or q. In our case and in order to simplify the control of stator po wer (acti v e or reacti v e), we use an orientation on the d axis. [2][12] Ho we v er: sd = s and sq = 0 (17) The e xpressions of the electromagnetic torque becomes: T em = 3 2 :p: M L s : sd :I r q (18) The e xpressions of the stator v oltages becomes: V sd = R s :I sd + d sd dt V sq = R s :I sq + sd :! s (19) F or medium and high po wer machines, stator resistances are ne glected [9], therefore the stator v oltage equations become: V sd = d sd dt V sq = sd :! s (20) In steady state, it is assumed that the flo w is constant, thus: V sd = 0 V sq = V s = s :! s (21) sd = s = L s :I sd + M :I r d sq = 0 = L s :I sq + M :I r q (22) From the equation (22), we deduce the equations linking between stator and rotor currents: I sd = s L s M L s :I r d I sq = M L s :I r q (23) The relations of the po wers become : P s = V sq :I sq Q s = V sq :I sd (24) T o e xpress the po wer relations as a funct ion of the rotor currents, we replace in the pre vious equation the currents by the equation (23): P s = V s :M L s :I r q Q s = V s 2 L s :! s V s :M L s :I r d (25) IJECE, V ol. 9, No. 3, June 2018 : 1531 – 1540 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 r 1535 By replacing flux and stator currents in the equation (13) by the e xpression (23) we obtain: r d = ( L r M 2 L s ) :I r d + V s:M L s :! s r q = ( L r M L s ) :I r q (26) In order to control the generator ,these e xpressions are established sho wing the relationship between the currents and the rotor v oltages that will be applied to it. V r d = R r :I r d + ( L r M 2 L s ) : dI r d dt g :! s : ( L r M 2 L s ) :I q r V r q = R r :I r q + ( L r M 2 L s ) : dI r q dt g :! s : ( L r M 2 L s ) :I dr + g : M :V s L s (27) It e xists tw o methods of Field Orientation Control: [16] 5.1. Dir ect Field Orientation Contr ol (DFOC) This method consists on re gulating the acti v e and reacti v e stator po wers of DFIG independently , by using a PI controller on each axis, while ne glecting the coupling terms between the tw o ax es. This method is called direct because the PI controller act directly on the v oltages[15][16]; The figure bello w sho ws the model of direct field orientation control; Figure 2. Direct field orientation control 5.2. Indir ect Field Orientation Contr ol(IFOC) Unlik e direct control and in order to re gulate the po wers as well as the currents rotor . This method tak es into consideration the coupling terms and puts tw o PI controllers on each axis [2].The figure bello w sho ws the model of indirect field orientation control; Figure 3. Indirect field orientation control Dir ect and indir ect vector contr ol of ... (Manale Bouderbala) Evaluation Warning : The document was created with Spire.PDF for Python.
1536 r ISSN: 2088-8708 6. RESUL T AND AN AL YSIS The simulation w as performed in the Matlab/Simulink en vironment; In order to model the wind, we use harmonic sums corresponding to the pulse ! . It is modeled by the follo wing equation: V = V 0 + n X i =1 A i : sin( ! i t + i ) (28) After applying a random wind profile as sho wn in 4, from the as sho wn in 5 and as sho wn in 6, it is clear that the system with MPPT control has the coef ficient of po wer Cp maintained at its maximum v alue Cp=0.5 and the P aer correctly follo ws the wind speed,unlik e the system without MP PT control. As well as as sho wn in 7 illustrates the ratio which is equal to its optimal v alue. Figure 4. W ind speed Figure 5. Aerodynamic po wer Figure 6. Cp coef ficient Figure 7. The ratio T o visualize the beha vior of the system controls and to be able to compare between the tw o commads we applied an acti v e and reacti v e po wer steps. The acti v e and reacti v e po wer steps, which are applied to each type of control, are sho wn in T able 1. T able 1. Acti v e and Reacti v e Po wer Steps T imes(s) Ps(MW) times(s) Qs(MV ar) 0 to 0,4 -0.6 0 to 0,2 -0.6 0,4 to 1,5 -1 0,2 to 1,5 -1 1,5 to 2,5 -1.2 1,5 to 10 -1.2 2,5 to 10 -4 The Figure8 and Figure9 sho w the acti v e and reacti v e po wer with direct control, then Figure10 and Figure11 sho w rotoric current Ird ant Irq. The Figure12 and Figure13 sho w the acti v e and reacti v e po wer with indirect control, and then Figure14 and Figure15 sho w the rotor current Ird and Irq. IJECE, V ol. 9, No. 3, June 2018 : 1531 – 1540 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 r 1537 Figure 8. Ps of DFOC Figure 9. Qs of DFOC Figure 10. Ird of DFOC Figure 11. Irq of DFOC Figure 12. Ps of IFOC Figure 13. Qs of IFOC Figure 14. Ird of IFOC Figure 15. Irq of IFOC From the pre vious figures we can see that, acti v e stator po wer (Ps) depend on the quadrature rotor current (Irq), and also reacti v e stator po wer (Qs) depend on the direct rotor current (Ird). So in both cases ( DFOC , IFOC) the decoupling is perfectly ensured. In the same figures; the system follo ws the applied instructions e xcept that at the le v el of the indirect field oriented control we can see v ery well that, it follo ws the instruction better than the direct control either for the po wers or the currents. The follo wing table summarizes the comparison of the tw o types of control in terms of response t ime (T r) and Ov ertaking (O). It is seen that the IFOC control lead to good tracking performance. Dir ect and indir ect vector contr ol of ... (Manale Bouderbala) Evaluation Warning : The document was created with Spire.PDF for Python.
1538 r ISSN: 2088-8708 T able 2. Dif ference between DFOC/IFOC Direct Indirect Rt(ms) O% Rt(ms) O% Ps 50 17,5 3 0 Qs 60 13,3 5 0 Ird 50 9,52 4 0 Irq 60 16,66 4 0 7. CONCLUSION this article deals with the impro v ement of the po wer generated from a wind po wer sys tem. After modeling the whole system ( wind turbine and DFIG generator) ,fisrt of all , we started with MPPT control to ensure maximum po wer e xtraction by fixing Cp at its maximum v alue . After that, we are interested in v ector control which consists in making the machine similar to a DC machine. Finally , we ha v e ha v e compared the tw o types of control DFOC and IFOC . In order to v alidate our study , we ha v e carried out the simulation in the Matlab/Simulink en vironment . Based on the simulation results, the MPPT control allo ws us to e xploit the maximum of wind ener gy to produ c e the maximum of electrical ener gy . Also, the v ector control is applied carefully . Moreo v er , we constated that, direct control which is based only on po wer re gulation, is the easiest to implement b ut not the most ef ficient. On the other hand, the indirect control where the currents are also controlled is a little comple x to implement, b ut, it ensures a good trac k i ng of the instruction and allo ws us to ha v e an optimal performance of the system. REFERENCES [1] T . Ack ermann and Soder , L. ” An Ov ervie w of W ind Ener gy-Status 2002 ”, Rene w able and Sustainable Ener gy Re vie ws , 6(1-2), 67-127 (2002). [2] S.Mensou, A.Essadki, T .Nasser , B.B.Idrissi, ”An Ef ficient Nonlinear Backstepping Cont roller Approch of a wind Po wer Generation System based on a DFIG”, International Journal of Rene w able Ener gy Research , V ol.7, No 4, pp.1520-1528, December 2017. [3] H.Alami, E.Ziani, B.Bossoufi, ”Speed control of the doubly fed induction generator applied to a wind system” Journal of Theoretical and Appli ed Information T echnology , pp426-433, V ol.83 No.3, January 2016. [4] A. Boualouch, A. Essadki, T . Nasser , A. Boukhriss, A. Frigui, “Po wer Control of DFIG in WECS Us- ing Backstipping and Sliding Mode Controller”, International Journal of Electrical Computer Ener getic Electronic and Communication Engineering , v ol. 9, pp. 612-618, 2015. [5] B.Bossoufi, S.Ionita, H.Alami Arroussi, M.El Ghamrasni, Y .Ihedrane ”Managing v oltage drops a v ari- able speed wind turbine connected to the grid”, IJ AA C International Journal of Automation and Control , V ol.11, No. 1, January 2017. [6] B.Bossoufi, M.Karim, A.Lagrioui, M.T aoussi, A.Derouich ”Observ er Backstepping control of DFIG- Generators for W ind T urbines V ariable-Speed: FPGA-Based Implementation”, Rene w able Ener gy Journal (ELSIVER) , pp 903-917, V ol. 81, September 2015. [7] M. El Azzaoui, H. Mahmoudi, K. Boudaraia, “Backstepping Cont rol of wind and photo v oltaic h ybrid Rene w able Ener gy System”. International Journal of Po wer Electronics and Dri v e Systems , V ol.7, pp 677- 686, September 2016 [8] B.Bossoufi, M.Karim, A.Lagrioui, M.T aoussi, M.L.El Hafyani ”Backstepping control of DFIG Generators for W ide-Range V ariable-Speed W ind T urbines ” IJ AA C International Journal of Automation and Control , pp 122-140, V ol.8 No.2, July 2014. [9] S. Mensou, A. Essadki, I. Minka, T . Nasser and B. B. Idrissi, ”Backstepping Controller for a V ariable W ind Speed Ener gy Con v ersion System Based on a DFIG, ” IEEE International Rene w able and Sustainable Ener gy Conference (IRSEC) , pp. 1-6, December 2017. [10] B.Bossoufi, M.Karim, A.Lagrioui, M.T aoussi ”FPGA-Based Implementation nonlinear Backstepping control of a PMSM Dri v e” IJPEDS International Journal of Po wer Electronics and Dri v e System , pp 12-23 V ol.4 No.1, March 2014. IJECE, V ol. 9, No. 3, June 2018 : 1531 – 1540 Evaluation Warning : The document was created with Spire.PDF for Python.
IJECE ISSN: 2088-8708 r 1539 [11] G. Poddar and V . T . Rang anathan, ”Sensorless Double-In v erter -Fed W ound-Rotor Induction-Machine Dri v e, ” IEEE T rans. Ind. Electron. , V ol. 53, No.1, pp. 86–95, February 2006. [12] N. El Ouanjli, A. Derouich, A. El Ghzizal, A. Chebabhi, M. T aoussi, ”A comparati v e study between FOC and DTC controls of the Doubly Fed Induction Motor (DFIM) ”, IEEE International Conference on Electrical and Information T echnologies , Rabat- Morocco 2017. [13] N. El Ouanjli, M. T aoussi, A. Derouich, A. Chebabhi, A. El Ghzizal, B. Boussoufi “High Performance Direct T orque Control of Doubly Fed Induction Motor using Fuzzy Logic”, Gazi uni v ersity journal of science 31(2),2018. [14] M. T aoussi, M. Karim, D. Hammoumi, C. Elbakkali, B. Boss oufi, N. El Ouanjli, ”Comparati v e study between Backstepping adapti v e and Field-oriented control of the DFIG applied to wind turbines”, 3rd IEEE International Conference on Adv anced T echnologies for Signal and Image Processing , May 2017. [15] M. Nadour , A. Essa dk i , T . Nass er . “Comparati v e Analysis between PI & Backstepping Control Strate gies of DFIG Dri v en by W ind T urbine”, International Journal of Rene w able Ener gy Research V ol. 7, No 3, pp. 1307-1. [16] Y . Ihedrane, C. El Bekkali , B. Bossoufi, “Po wer Control of DFIGGenerators for W ind T urbines V ariable Speed”, International Journal of Po wer Electronics and Dri v e Systems , V ol. 8, pp. 444-453. March 2017. BIOGRAPHIES OF A UTHORS Manale Bouderbala is a Ph.D. Student in Electr ical Engineering from Higher school of tech- nology , Oujda Morocco. She is member of laboratory electrical engineering and maintenance (LGEM). She had her master’ s de gree in Engineering of Industrial Automated Systems at the F aculty of Sciences Dhar el Mahrez Fez. Her research interests include Rene w able Ener gy , static con v erters, electrical motor dri v es, and po wer electronics Badr e Bossoufi is a Professor of Electrical Engineering, at the Higher School of technology , Oujda Morocco. He is member of laboratory electri cal engineering and maintenance(LGEM). He recei v ed the Ph.D. de gree in Electrical Engineering from Uni v ersity Sidi Mohammed Ben Abdellah, F aculty of Sciences, Morocco and PhD de gree from Uni v ersity of Pitesti, F aculty of Electronics and Computer , Romanie and Montefiore Institute of electrical engineering, Luik, Belgium. his research inter ests include static con v erters, electr ical motor dri v es, po wer electronics, Smart Grid, Rene w able Ener gy and Artificial Intelligent. Ahmed Lagrioui is a professor in ENSAM-Mekness, Uni v ersity Mly Smail, Morocco. He re- cei v ed the Ph.D. de gree in Electrical Engineering from the Mohammadia school’ s of engineers, Rabat, Morocco. He recei v ed the aggre g ation de gree in electrical engineering from the ENSET School, in 2003. He recei v ed t he DESA de gree in industrial electronics from the Mohammadia school’ s of engineers. His research interests include static con v erters, electrical motor dri v es and po wer electronics Mohammed T aoussi is a Ph.D. Student in Electrical Engineering from Uni v ersity Sidi Mo- hammed Ben Abdellah, F aculty of Sciences, Morocco. He recei v ed the MASTER de gree in industrial electronics from the F aculty of Sciences Fez, in 2013. His research interests include static con v erters, electrical motor dri v es, and po wer electronics, Smart Grid, Rene w able Ener gy and Artificial Intelligence. Dir ect and indir ect vector contr ol of ... (Manale Bouderbala) Evaluation Warning : The document was created with Spire.PDF for Python.
1540 r ISSN: 2088-8708 Hala Alami Ar oussi recei v ed her M.S de gree in Industrial Automated Systems Engineering from Sidi Mohammed Ben Abdellah Uni v ersity , Fez, Morocco. She is currently pursuing her Ph.D in Electrical Engineering at Mohamed first Uni v ersity , Oujda, Morocco. She is a member of laboratory of electrical engineering and maint enance (LGEM). Her research interests include modeling, control of wind ener gy con v ersion systems using a doubly fed induction machine and rene w able ener gy . Y asmine Ihedrane obtained her master’ s de gree in Engineering of Industrial Automated Systems at the F aculty of Sciences Dhar el Mahrez -FES- where she currently w orks, PhD. graduate stu- dent in the same uni v ersity and she is a member of laboratory (LIST A). Her interests in machine control. IJECE, V ol. 9, No. 3, June 2018 : 1531 – 1540 Evaluation Warning : The document was created with Spire.PDF for Python.