International Journal of Advance Engineering and Research Development

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1 Sientifi Journal of Imat Fator (SJIF): 5.71 International Journal of Advane Engineering and Researh Develoment Volume 5, Issue 04, Aril e-issn (O): ISSN (P): STUDY ON THE LOW-VOLTAGE RIDE-THROUGH PERFORMANCE OF BRUSHLESS DOUBLY FED RELUCTANCE GENERATOR UNDER SYMMETRICAL VOLTAGE DIPS P.K.Sarkar 1, P.K.Gayen 2, D.Chatterjee 3 1 Eletrial Engineering Deartment, Government College of Engg & Textile Teh, Berhamore, India. 2 Eletrial Engineering Deartment, Kalyani Government Engineering College, Nadia, India. 3 Eletrial Engineering Deartment, Jadavur University, Kolkata, W.B Abstrat- This aer resents the low-voltage ride-through (LVRT) erformane of brushless doubly fed relutane generator (BDFRG) under symmetrial voltage dis and reovery onditions. The BDFRG is found suitable alternative for generating eletrial energy from wind energy. The ower (rimary) winding of the mahine is diretly onneted to the three-hase loal/distribution grid and ontrol (seondary) winding is integrated to the same eletrial ower network through bak-to-bak (dual) onverter. In ratie, there is the ossibility of sudden di in the voltage of onneted grid and the voltage reovery starts after some elased time. Therefore, the aer fouses on the behavior of BDFRG from voltage di to reovery time san. The transient urrents in rimary winding, momentary torque ulsation and seed rise are the onsequenes under the abnormal ondition of symmetrial voltage dis and reovery. The ride-through erformanes of BDFRG are studied in this aer using MATLAB-SIMULINK software. Keywords- Brushless doubly fed relutane generator (BDFRG), low-voltage ride-through (LVRT), symmetrial voltage di, voltage reovery, torque ulsation. Nomenlature v, v Primary and seondary winding voltage resetively i, i Primary and seondary winding urrent resetively, Radian frequeny of rimary and seondary winding variables resetively rot Rotational seed in rad/se, No. of ole airs of rimary and seondary winding rot No. of ole airs of rotor T, T Eletromagneti and mehanial torque em m L, L Primary and seondary winding total indutane resetively L Mutual indutane R, R Primary and seondary winding total resistane resetively, Primary and seondary winding flux linkage resetively J Moment of inertia of rotor Conjugate oerator Sae vetor notation BDFRG Brushless Doubly Fed Relutane Generator I. Introdution In reent years, emhasis is given on the ultivation of wind eletrial energy [1]. For this urose, synhronous generator [2] an be emloyed for onstant seed oeration at the ost of lower effiieny of the onversion system. For variable seed oeration, doubly-fed indution generator (DFIG) [3] an be emloyed. But the ost of the DFIG is high and reliability is low due to resene of sli rings and brushes. The roblem of higher ost and low reliability an be overome by using brushless doubly fed indution generator [4]. Now a days, it has been found that brushless doubly fed relutane generator All rights Reserved 1491

2 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: an be effiiently used in wind energy onversion system (WECS) [5]. In BDFRG onet, the stator has two three-hase windings- namely, ower (rimary) and ontrol (seondary) windings and the rotor is salient ole relutane in nature [6]. The two stator windings must have different ole numbers so that they do not magnetially ouled diretly. The rotor is designed in suh a way that it hels to oule the magneti fields rodued by both stator windings. The ower winding is diretly onneted to the nearby grid and the ontrol winding is onneted to the same grid through bak-to-bak (dual) ontrolled onverter. This mahine has the advantage of artially rated ower eletronis onverter. In WECS, when the generator is onneted to the grid, should omly with grid ode [7]. Wind Turbine BDFRG Grid Wind Mehanial Couling Dual Converter Fig. 1: Loal grid onneted BDFRG The generator used in WECS, should remain onneted and suly reative ower to the grid under grid voltage dis [8]. Various ontrol strategies of BDFRG have been disussed in various ublished aers [9-16]. Performane of BDFRG under voltage harmonis has also been studied [17]. No signifiant study on low voltage ride-through (LVRT) erformane [18] of BDFRG has been notied to the best of authors knowledge. Therefore, this aer onentrates on the study on the LVRT erformane of BDFRG under symmetrial voltage dis ondition. The transient urrent in ower winding is notied due to sudden dis in grid voltage. As a result, the ative and reative ower osillations aeared in rimary winding of BDFRG. The torque osillation and seed rise is observed under the abnormal ondition of symmetrial voltage dis. This study will be helful to design a ontrol strategy for imroving LVRT aability of grid onneted BDFRG. The dynami modeling of BDFRG is disussed in setion II. Setion III desribes the LVRT erformane of BDFRG under symmetrial voltage dis ondition. Setion IV resents the results of simulation study. The aer onludes its findings in setion V. The aendix and referenes follow setion V. II. DYNAMIC MODELING OF BDFRG The dynami modeling of BDFRG has been disussed in [18]. The governing equations of BDFRG are resented in the following equations in sae vetor form as, d v Ri (1) d v L i L i (3) Ri (2) L i L i (4) The rotor seed and ole number are related to that of the rimary and seondary windings as given below, (5) rot rot (6) The dynami torque-seed equation governing the rotational motion of rotor is given All rights Reserved 1492

3 d T T J International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: rot m em (7) In Eq. (7), the eletromagneti torque is mathematially exressed as, 3 Tem j rot L[ i i ii ] (8) 4 The symbols used in Eq. (1)-(8) are desribed in the nomenlature setion. The d-q axis equations in stationary referene frame are exressed as, d v R i d v R i dd vd Rid q dq vq Riq d d d d q q q q d (9) (10) The exressions of ative and reative ower are given below, P i v i v (11) d d q q Q idvq iqvd (12) The d-q axis equivalent iruit diagram of BDFRG is shown in Fig. 2. Here, L, L denote leakage indutane of rimary and seondary windings resetively. The d-q axis equivalent iruit diagram of BDFRG is shown in Fig. 2. l l R L 1 1 L12 1 1q 2 2q 2 12 R2 i 1d L L i 2d v 1d L 12 v 2d R L 1 1 L12 1 1d 2 2d 2 12 R2 i 1q L L i 2q v 1q L 12 v III. LVRT PERFORMANCE OF BDFRG 2q (b) Fig. 2: d-axis model, (b) q- axis model of BDFRG The rimary voltage in sae vetor form under normal oerating ondition an be written resetively as, j t v V. e (13) v j dv. e t (14) In Eq. (14), d indiates deth of voltage di. The resulting rimary winding urrent onsists of two omonents as given All rights Reserved 1493

4 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: i it is (15) where, i t, i s denotes the transient and steady state art of the rimary urrent. The transient and steady state art of the rimary urrent is exressed as, t / i dv R. e (16) t j t is (1 d) V R. e (17) L R. where, The eletromagneti torque under voltage dis situation is mathematially reresented as, T em 3 j L i i i i rot [ t s t s 4 it is it is ] (18) IV. Results The MATLAB-SIMULINK software is used to develo the model of three-hase grid onneted BDFRG for studying the LVRT erformane of BDFRG under symmetrial voltage dis situation. The seifiations of the BDFRG are rovided in Aendix. In this simulation study, the model is run for total simulation time san of 15 se in SIMULINK latform. The voltage dis starts at simulation time t = 6 se. Tn this study, the voltage di deth d is taken as 0.6.u.. After that, the voltage reovery starts at t = 6.5 se. The rimary winding voltage reovers to its normal value at time t= 7 se. The rofile of a-hase rimary winding voltage is shown in Fig. 3. Fig.3: a-hase rimary voltage waveform The a-hase seondary winding voltage in the study is shown in Fig. 4. Fig.4: a-hase seondary winding voltage waveform The urrent waveforms of rimary and seondary windings in the study are resented in Fig. 5. Fig. 5 shows that the rimary urrent transient deays and settles to steady state value during voltage dis. During reovery eriod, the rimary urrent rams u to the normal All rights Reserved 1494

5 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: (b) Fig.5: a-hase urrent in rimary and (b) seondary windings The obtained ative and reative ower at rimary winding is shown in Fig. 6. (b) Fig.6: Three-hase ative and (b) reative ower at rimary winding The orresonding d-axis and q-axis rimary winding fluxes are shown in Fig. 7. The obtained torque and seed resonses during normal, voltage dis and reovery are reresented in Fig. 8. The inut mehanial torque is resented in Fig. All rights Reserved 1495

6 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: Fig.7: d-axis and (b) q-axis rimary winding flux. (b) Fig.8: Eletromagneti torque and (b) rotor seed Fig.9: Inut mehanial All rights Reserved 1496

7 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: V. CONCLUSION This aer studies on the low-voltage ride-through erformane of three-hase grid onneted BDFRG under symmetrial grid voltage dis. The sudden voltage dis in rimary winding reate transient urrent in this winding. The eak value of the transient urrent is not high like the ase DFIG whih is widely used in WECS. The flux in the rimary winding of BDFRG is of deaying osillatory in nature after voltage dis. The signifiant amount of ulsation in eletromagneti torque is also notied in the study. The rise in seed indiates the inrement of stored energy into the rotor of the mahine. The ative ower ulsation and redution of reative ower in the rimary winding are also two imortant onsequenes under symmetrial voltage dis ondition. This study will be helful to frame suitable LVRT ontrol strategy for BDFRG to mitigate or redue the undesired behavior of BDFRG in the abnormal ondition. Aendix PARAMET ERS Power Voltage R, L R, L L J,, rot TABLE I SPECIFICATIONS OF BDFRG VALUES 1.5 kw 10.7 Ω, H Ω, H 0.57 H 0.1 kg/m 2 6,2,4 415 V REFERENCES [1] M. Glinkowski, J. Hou, and G. Rakliffe, Advanes in wind energy tehnologies in the ontext of smart grid, Pro. IEEE, vol. 99, no. 6, , Jun [2] M. Cheah-Mane, J. Liang, and N. Jenkins, Permanent magnet synhronous generator for wind turbines: Modelling, ontrol and inertial frequeny resonse, in Pro. 49th Int. Univ. Power Eng. Conf., Se.2014, [3] S. Muller, M. Deike, and R. W. De Donker, Doubly fed indution generator systems for wind turbines, IEEE Ind. Al. Mag., vol. 8, no. 3, , May/Jun [4] T. Logan, J. Warrington, S. Shao, and R. MMahon, Pratial deloyment of the Brushless Doubly-Fed Mahine in a medium sale wind turbine, 2009 International Conferene on Power Eletronis and Drive Systems (PEDS), , Nov [5] M. G. Jovanović, R. E. Betz, and J. Yu, The use of doubly fed relutane mahines for large ums and wind turbines, IEEE Trans. Ind. Al., vol. 38, no. 6, , Nov./De [6] A. Knight, R. Betz, and D. Dorrell, Design and analysis of brushless doubly fed relutane mahines, IEEE Trans. Ind. Al., vol. 49, no. 1, , Jan./Feb [7] R. Piwko, N. Miller, R. Girad, J. MaDowell, and K. Clark, Generator fault tolerane and grid odes, IEEE Power Energy Mag., vol. 8, no. 2, , Mar [8] Y. Zhang, Z. Duan, and X. Liu, Comarison of grid ode requirements with wind turbine in hina and euroe, in Pro. Asia-Paifi Power Energ.Eng. Conf., 2010, [9] R. E. Betz and M. G. Jovanović, Theoretial analysis of ontrol roerties for the brushless doubly fed relutane mahine, IEEE Trans. Energy Convers., vol. 17, no. 3, , Se [10] M. Jovanovi, Sensored and sensorless seed ontrol methods for brushless doubly fed relutane motors, IET Elet. Power Al., vol. 3, no. 6, , [11] S.Ademi and M. G. Jovanović, Vetor Control Methods for Brushless Doubly Fed Relutane Mahines, IEEE Trans. Ind. Eletron., vol. 62, no. 1, , Jan. All rights Reserved 1497

8 International Journal of Advane Engineering and Researh Develoment (IJAERD) Volume 5, Issue 04, Aril-2018, e-issn: , rint-issn: [12] L. Xu, L. Zhen, and E. Kim, Field-orientation ontrol of a doubly exited brushless relutane mahine, IEEE Trans. Ind. Al., vol. 34, no. 1, , Jan./Feb [13] M. G. Jovanović, J. Yu, and E. Levi, Enoderless diret torque ontroller for limited seed range aliations of brushless doubly fed relutane motors, IEEE Trans. Ind. Al., vol. 42, no. 3, , May/Jun [14] H. Chaal and M. G. Jovanović, Power ontrol of brushless doubly-fed relutane drive and generator systems, Renew. Energy, vol. 37, no. 1, , [15] H. Chaal and M. G. Jovanović, Toward a generi torque and reative ower ontroller for doubly fed mahines, IEEE Trans. Power Eletron., vol.27, no. 1, , Jan [16] H. Chaal and M. G. Jovanović, Pratial imlementation of sensorless torque and reative ower ontrol of doubly fed mahines, IEEE Trans. Ind. Eletron., vol. 59, no. 6, , Jun [17] P.K. Sarkar, P.K. Gayen, Study on the Performane of Brushless Doubly Fed Relutane Generator under Voltage Harmonis, IJARSE, vol. no-07, Seial issue no-04, age no [18] T. Long, S. Shao, E. Abdi, P. Malliband, M. E. Mathekga, R. A. Mmahon, and P. J. Tavner, Symmetrial low voltage ride-through of a 250 kw brushless dfig under a symmetrial full voltage di, in Pro. 6th IET Int. Conf. Power Eletron. Mah. Drives, Mar. 2012,. All rights Reserved 1498