14 12 2010 12 ELECTRI C MACHINES AND CONTROL Vol. 14 No. 12 Dec. 2010 DFIG 400044 doubly fed induction generators DFIG DFIG DFIG DFIG DFIG DFIG DFIG TM 614 A 1007-449X 2010 12-0001- 08 Coordinated control of a doubly fed induction generator wind turbine with series grid-side converter under unbalanced grid voltage conditions YAO Jun LIAO Yong LI Hui State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing 400044 China Abstract The operation conditions of the doubly fed induction generator DFIG wind turbine with series grid-side converter under unbalanced grid voltage conditions are investigated in this paper. In order to restrain the unbalanced stator voltage and maintain the active power balance the control strategies for the and parallel grid-side converter GSC are proposed respectively. Compared with the traditional control scheme of the DFIG system the control strategy of the rotor-side converter RSC would not be changed during network unbalance and it is helpful to simplify the control of RSC and improve the operational reliability of RSC. Not only the double supply frequency oscillations in electromagnetic torque DC-link voltage and total active power output can be eliminated but also the stator and rotor currents of the system are balanced. The operational stability and reliability of the DFIG system can be further improved with the proposed scheme. The simulations and contrastive analysis between the DFIG system with and DFIG system with traditional control strategy verify the validity and effectiveness of the proposed coordinated control strategy. Key words wind-power generation doubly fed induction generators DFIG unbalanced grid voltage series grid-side converters coordinated control 2010-04 - 17 863 2007AA05Z422 CSTC 2008AB3047 2007DA10512709214 1979 1964 1983
2 14 0 DFIG DFIG doubly fed induction generators DFIG series grid - side converters DFIG 10 - DFIG 12 DFIG 1 DFIG DFIG 10-12 DFIG SG- SC DFIG 2MW DFIG 1 DFIG 1. 1 2-3 DFIG DFIG 11-1 12 DFIG 3-9 4 7 GSC RSC PWM rotor - side converters RSC DFIG / grid - side converters GSC RSC u s = u series + u g 1 GSC u s u series u g RSC GSC g s r DFIG series + - + -
12 DFIG 3 1 u gαβ = u gαβ + + u gαβ - 2 DFIG Fig. 1 Configuration of DFIG system with u gαβ - DFIG DFIG u seriesαβ - = - u gαβ - 3 k t u series = u com + - u gαβ - k t 5 u com + 4 DFIG GSC 7 DFIG P g = P g - av + P g - sin2sin2ωt + P g - cos2cos2ωt Q g = Q g - av + Q g - sin2sin2ωt + Q g - cos2cos2ωt 9 dq S series = P series + jq series = u series i^ series = u series = u com + P series - av + P series - cos2cos2ωt + P series - sin2sin2ωt + j Q series - av + Q series - cos2cos2ωt + Q series - sin2sin2ωt 6 - u gαβ - k t = comd + + j comq + e jωt - k t + j e - jωt i series = k t i s = k t i s + = k t i + sd + + ji + sq + e jωt 7 av sin2 cos2 ω 6 P series - av Q series - av P series - cos2 P series - sin2 Q series - cos2 Q series - sin2 = comd + comq + comq + - comd + - - - - i + sd + [ i ] + sq + 8 k t 1. 2 RSC DFIG DFIG DFIG DFIG RSC DFIG u sαβ = u sαβ + = u gαβ + 4 DFIG 1. 3 GSC GSC GSC dq 9 P g - av Q g - av P g - cos2 P g - sin2 Q g - cos2 Q g - sin2 = - - - - - - - - i + i + i - i - 10 10
4 14 GSC GSC 11 1 GSC 2 GSC 3 2ω GSC DFIG GSC GSC = K seriesdq + p1 τ i1 s + 1 /τ i1 s gdq + - sdq + = K seriesdq - p2 τ i2 s + 1 /τ i2 s 0 - sdq - GSC 14 K p1 τ i1 PI GSC K p2 τ i2 PI 2 DFIG DFIG RSC RSC RSC RSC GSC 2. 1 voltage unbalance 14 u s+ = u g+ 11 u s- = 0 u g = u g+ + u g- 12 DFIG 1 u g e - jωt = gdq + + gdq - e - j2ωt = + j + K p1 < 0 K p2 < 0 2 + j e - j2ωt 13 1 2 C du2 dc = P g - P r - P series 15 2ω RSC 15 2ω GSC 2 Fig. 2 Control diagram of during grid 2. 2 GSC 1. 3 RSC GSC
12 DFIG 5 P * g - av = 2-2 - 2 = 0 1 2 C du2 dc = P g - P r - P series = P g - av - P r - P series - av + P g - cos2 - P series - cos2 = 0 P g - sin2 - P series - sin2 = 0 21 d = - R g i - di - PLL 8 q - = - R g i - - L g d d = g + = 0 22 θ g + = θ ug + θ g - = - θ g + q + = - K p3 τ i3 s + 1 /τ i3 s gq+ - i + gq+ - ωl g i + i -* 10 21 GSC = P series - cos2 gd+ gd+ - gd+ P ~ g t - P ~ i -* = P series - sin2 series t 16 gd+ gd+ gd+ U dc * P series - cos2 P series - sin2 8 i + * = 0 GSC U 2 dc t = U dc - av + U ~ P * dc t 2 U 2 g - av GSC dc - av + 2U dc - av U ~ dc t 17 GSC PI 16 17 GSC 16 P g - av - 13 P r - P series - av P * g - = K pu τ iu s + 1 /τ iu s U * dc - U dc U * dc 24 du ~ K pu τ iu PI dc 1 = P ~ CU g t - P ~ series t 18 dc - av 1 DFIG U ~ DFIG dc t = U dc - sin2sin2ωt + U dc - cos2cos2ωt 19 - - + 23 1 P U dc - sin2 = P 2ωCU g - cos2 - P series - cos2 dc - total = P s - P series + P g = P s - P series - av + P g - av + av - P series - sin2 + P g - sin2 sin2ωt + 20 1 - P series U dc - cos2 = - P 2ωCU g - sin2 - P series - sin2 - cos2 + P g - cos2 cos2ωt 25 dc - av 21 25 GSC dq 13 GSC di + d + = - R g i + - L g GSC di + GSC q + = - R g i + - L g d - di - - L g + ωl g i + + - ωl g i + - ωl g i - + ωl g i - + + 26 27 R g L g 23 26 27 dq GSC d + = - K p3 τ i3 s + 1 /τ i3 s gd+ - i + gd+ + ωl g i + + 28
6 14 d - = - K p4 τ i4 s + 1 /τ i4 s i -* - i - - ωl g i - + q - = - K p4 τ i4 s + 1 /τ i4 s i -* - i - + ωl g i - + 29 K p3 τ i3 PI 0. 03pu K p4 τ i4 PI 5 K p1 = - 1 K p2 = - 6 6 GSC K p3 = 0. 1 K p4 = 0. 1 3 4 DFIG DFIG GSC 4 200kW 50Hz 1 7 0. 006pu 4 8% 8% 3 Fig. 3 GSC Control diagram of GSC during grid voltage unbalance 3 DFIG DFIG Matlab /SIMULINK 2MW 15Hz DFIG s = - 0. 3 115Hz DFIG 5 d 5 e 5 f ~ 5 k DFIG DFIG 1 DFIG 2MW 690V /50Hz Y y 2 0. 45 1 0. 004 88pu 0. 138 6pu 1 0. 005 49pu 0. 149 3pu Table 1 3. 952 7pu 3. 5s Comparisons of control performances % 2 2. 5MVA 50Hz 20kV - Delta 690V - Yg Z T = 0. 009 8 + j0. 092 41pu 3 GSC 6mΩ DFIG 0. 6mH 38 000μF 1 200V Fig. 4 4 DFIG Configuration of DFIG system 5 6 DFIG DFIG DFIG 1 950r /min A 2. 0s 28 29 2. 6s GSC DFIG DFIG 5 b 5 c DFIG 0. 32 0. 56 0 ± 0. 64 ± 0. 32 ± 0. 8 8 7. 44 6. 32 ± 15. 2 ± 1. 6 ± 4
12 DFIG 7
8 14 5 6 33 15 89-93. DFIG RSC DFIG lectronics 2008 23 3 GSC GUO Xiaoming et al. Modeling and control of the DFIG Based wind-power generation system under unbal- 6 k HU Jiabing HE Yikang 6 g 6 h GSC anced grid voltage conditions J Systems 2007 31 14 47-56. 20 25 Transactions on Energy Conversion 2007 22 1 129-135. 7 HU Jiabing 4 DFIG VENKATARAMANAN G. A fault tolerant doubly fed induction generator wind turbine using a parallel grid side rec- DFIG DFIG 9 BREKKEN T DFIG GSC Conference June 15-19 2003 Acapulco Mexico. - 764. 10 FLANNERY P DFIG tifier and series grid side converter J 1 PIWKO R MILLER N GASCA J S et al. Integrating large wind farms into weak power grids with long transmission lines C Proceedings of IEEE 5th International Power Electronics and Motion Control Conference August 14-16 2006 Shanghai China. 2006. 2 MULJADI E YILDIRIM D BATAN T et al. Understanding the unbalanced-voltage problem in wind turbine generation C Proceedings of 34th IAS Annual Meeting October 3-7 1999 Phoenix USA. 1999 1359-1365. 3. 13. PWM. J. 2009 33 15 89-93. 2003. ZHENG Yanwen LI Yongdong CHAI Jianyun et al. Research on control strategy for doubly-fed generation system under unbalanced voltage condition J. Automation of Electric Power Systems 2009 4 XU Lie. Coordinated control of DFIG s rotor and grid side converters during network unbalance J. IEEE Transactions on Power E- 1041-1049. 5. J. 2007 31 14 47-56.. Automation of Electric Power 6 BREKKEN T MOHAN N. Control of a doubly fed induction wind generator under unbalanced grid voltage conditions J. IEEE HE Yikang. Reinforced control and operation of DFIGbased wind-power-generation system under unbalanced grid voltage conditions J. IEEE Transactions on Energy Conversion 2009 24 4 905-915. 8 XU L WANG Y. Dynamic modeling and control of DFIG based wind turbines under unbalanced network conditions J. IEEE Transactions on Power Systems 2007 22 1 314-323. MOHAN N. A novel doubly-fed induction wind generator control scheme for reactive power control and torque pulsation compensation under unbalanced grid voltage conditions C Proceedings of the IEEE 34th Annual Power Electronics Specialists 2003 760 Power Electronics 2008 23 3 1126-1135.. IEEE Transactions on 11 FLANNERY P VENKATARAMANAN G. Unbalanced voltage sag ride-through of a doubly fed induction generator wind turbine with series grid-side converter J. IEEE Transactions on Industry Applications 2009 45 5 1879-1887. 12. J. 2009 29 27 90-98. LIAO Yong LI Hui YAO Jun et al. Low voltage ride-through control strategy of a doubly fed induction generator wind turbine with series grid - side converter J. Proceedings of the CSEE 2009 29 27 90-98.