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Volumn 61, Issue 5, 2014, Pages 2139-2151

An adaptive prefiltering method to improve the speed/accuracy tradeoff of voltage sequence detection methods under adverse grid conditions

Author keywords

Distributed generation; generalized integrators; grid offset voltage rejection; grid voltage sequence detection; power quality; subharmonic rejection; voltage sags

Indexed keywords

DISTRIBUTED POWER GENERATION; HARMONIC ANALYSIS; SIGNAL DETECTION;

EID: 84887051347     PISSN: 02780046     EISSN: None     Source Type: Journal    
DOI: 10.1109/TIE.2013.2274414     Document Type: Article
Times cited : (219)

References (51)
  • 1
    • 82955224780 scopus 로고    scopus 로고
    • The need to limit subharmonics injection
    • Oct
    • J. P. G. de Abreu and A. E. Emanuel, "The need to limit subharmonics injection," in Proc. 9th ICHQP, Oct. 2000, vol. 1, pp. 251-253
    • (2000) Proc. 9th ICHQP , vol.1 , pp. 251-253
    • De Abreu, J.P.G.1    Emanuel, A.E.2
  • 2
    • 77955209745 scopus 로고    scopus 로고
    • Analysis of sub-harmonics in power systems
    • Z. Leonowicz, "Analysis of sub-harmonics in power systems," in Proc. Int. Conf. EEIC, 2010, pp. 125-127
    • (2010) Proc. Int. Conf. EEIC , pp. 125-127
    • Leonowicz, Z.1
  • 4
    • 27844452970 scopus 로고    scopus 로고
    • On the interharmonic components generated by adjustable speed drives
    • DOI 10.1109/TPWRD.2005.852313
    • F. De Rosa, R. Langella, A. Sollazzo, and A. Testa, "On the interharmonic components generated by adjustable speed drives," IEEE Trans. Power Del., vol. 20, no. 4, pp. 2535-2543, Oct. 2005 (Pubitemid 41638229)
    • (2005) IEEE Transactions on Power Delivery , vol.20 , Issue.4 , pp. 2535-2543
    • De Rosa, F.1    Langella, R.2    Sollazzo, A.3    Testa, A.4
  • 6
    • 0036866623 scopus 로고    scopus 로고
    • Flicker sources and mitigation
    • Nov
    • M. M. Morcos and J. C. Gomez, "Flicker sources and mitigation," IEEE Power Eng. Rev., vol. 22, no. 11, pp. 5-10, Nov. 2002
    • (2002) IEEE Power Eng. Rev , vol.22 , Issue.11 , pp. 5-10
    • Morcos, M.M.1    Gomez, J.C.2
  • 7
    • 70350268072 scopus 로고    scopus 로고
    • Phasor estimation in the presence of DC offset and CT saturation
    • Oct
    • N. Soon-Ryul, P. Jong-Young, K. Sang-Hee, and M. Kezunovic, "Phasor estimation in the presence of DC offset and CT saturation," IEEE Trans. Power Del., vol. 24, no. 4, pp. 1842-1849, Oct. 2009
    • (2009) IEEE Trans. Power Del , vol.24 , Issue.4 , pp. 1842-1849
    • Soon-Ryul, N.1    Jong-Young, P.2    Sang-Hee, K.3    Kezunovic, M.4
  • 9
    • 0032118569 scopus 로고    scopus 로고
    • Characterization of voltage sags in industrial distribution systems
    • PII S0093999498049093
    • G. Yalcinkaya, M. H. Bollen, and P. A. Crossley, "Characterization of voltage sags in industrial distribution systems," IEEE Trans. Ind. Appl., vol. 34, no. 4, pp. 682-688, Jul./Aug. 1998 (Pubitemid 128740201)
    • (1998) IEEE Transactions on Industry Applications , vol.34 , Issue.4 , pp. 682-688
    • Yalcinkaya, G.1
  • 10
    • 0038493865 scopus 로고    scopus 로고
    • Algorithms for characterizing measured three-phase unbalanced voltage dips
    • Jul
    • M. H. Bollen, "Algorithms for characterizing measured three-phase unbalanced voltage dips," IEEE Trans. Power Del., vol. 18, no. 3, pp. 937-944, Jul. 2003
    • (2003) IEEE Trans. Power Del , vol.18 , Issue.3 , pp. 937-944
    • Bollen, M.H.1
  • 11
    • 0033350974 scopus 로고    scopus 로고
    • Dual current control scheme for PWM converter under unbalanced input voltage conditions
    • DOI 10.1109/41.793344
    • H. Song and K. Nam, "Dual current control scheme for PWM converter under unbalanced input voltage conditions," IEEE Trans. Ind. Electron., vol. 46, no. 5, pp. 953-959, Oct. 1999 (Pubitemid 30524489)
    • (1999) IEEE Transactions on Industrial Electronics , vol.46 , Issue.5 , pp. 953-959
    • Song, H.-S.1    Nam, K.2
  • 13
    • 80051709438 scopus 로고    scopus 로고
    • Mitigation of dynamic, unbalanced, and harmonic voltage disturbances using grid-connected inverters with LCL filter
    • Sep
    • Y. A.-R. I. Mohamed, "Mitigation of dynamic, unbalanced, and harmonic voltage disturbances using grid-connected inverters with LCL filter," IEEE Trans. Ind. Electron., vol. 58, no. 9, pp. 3914-3924, Sep. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.9 , pp. 3914-3924
    • Mohamed, Y.A.-R.I.1
  • 14
  • 15
    • 78650181509 scopus 로고    scopus 로고
    • Hierarchical control of droop-controlled AC and DC microgrids-A general approach toward standardization
    • Jan
    • J. M. Guerrero, J. C. Vasquez, J. Matas, L. G. de Vicuna, and M. Castilla, "Hierarchical control of droop-controlled AC and DC microgrids-A general approach toward standardization," IEEE Trans. Ind. Electron., vol. 58, no. 1, pp. 158-172, Jan. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.1 , pp. 158-172
    • Guerrero, J.M.1    Vasquez, J.C.2    Matas, J.3    De Vicuna, L.G.4    Castilla, M.5
  • 16
    • 33750109723 scopus 로고    scopus 로고
    • Overview of control and grid synchronization for distributed power generation systems
    • DOI 10.1109/TIE.2006.881997
    • F. Blaabjerg, R. Teodorescu, M. Liserre, and A. V. Timbus, "Overview of control and grid synchronization for distributed power generation systems," IEEE Trans. Ind. Electron., vol. 53, no. 5, pp. 1398-1409, Oct. 2006 (Pubitemid 44593490)
    • (2006) IEEE Transactions on Industrial Electronics , vol.53 , Issue.5 , pp. 1398-1409
    • Blaabjerg, F.1    Teodorescu, R.2    Liserre, M.3    Timbus, A.V.4
  • 17
    • 78650895883 scopus 로고    scopus 로고
    • Grid-fault control scheme for three-phase photovoltaic inverters with adjustable power quality characteristics
    • Dec.
    • M. Castilla, J. Miret, J. L. Sosa, J. Matas, and L. García de Vicuña, "Grid-fault control scheme for three-phase photovoltaic inverters with adjustable power quality characteristics," IEEE Trans. Power Electron., vol. 25, no. 12, pp. 2930-2940, Dec. 2010
    • (2010) IEEE Trans. Power Electron , vol.25 , Issue.12 , pp. 2930-2940
    • Castilla, M.1    Miret, J.2    Sosa, J.L.3    Matas, J.4    Vicuña De García, L.5
  • 18
    • 84876269105 scopus 로고    scopus 로고
    • A phasor estimator for synchronization between power grid and distributed generation system
    • Aug.
    • C.-I. Chen, "A phasor estimator for synchronization between power grid and distributed generation system," IEEE Trans. Ind. Electron., vol. 60, no. 8, pp. 3248-3255, Aug. 2013
    • (2013) IEEE Trans. Ind. Electron , vol.60 , Issue.8 , pp. 3248-3255
    • Chen, C.-I.1
  • 19
    • 84878147999 scopus 로고    scopus 로고
    • Frequency-adaptive current controller for three-phase grid-connected converters
    • Oct.
    • S. Gomez Jorge, C. A. Busada, and J. A. Solsona, "Frequency-adaptive current controller for three-phase grid-connected converters," IEEE Trans. Ind. Electron., vol. 60, no. 10, pp. 4169-4177, Oct. 2013
    • (2013) IEEE Trans. Ind. Electron , vol.60 , Issue.10 , pp. 4169-4177
    • Gomez Jorge, S.1    Busada, C.A.2    Solsona, J.A.3
  • 20
    • 84857422425 scopus 로고    scopus 로고
    • Current controller based on reduced order generalized integrators for distributed generation systems
    • Jul.
    • C. A. Busada, S. Gomez Jorge, A. E. Leon, and J. A. Solsona, "Current controller based on reduced order generalized integrators for distributed generation systems," IEEE Trans. Ind. Electron., vol. 59, no. 7, pp. 2898-2909, Jul. 2012
    • (2012) IEEE Trans. Ind. Electron , vol.59 , Issue.7 , pp. 2898-2909
    • Busada, C.A.1    Gomez Jorge, S.2    Leon, A.E.3    Solsona, J.A.4
  • 21
    • 84873669101 scopus 로고    scopus 로고
    • Dynamics assessment of advanced single-phase PLL structures
    • Jun.
    • S. Golestan, M. Monfared, F. D. Freijedo, and J. M. Guerrero, "Dynamics assessment of advanced single-phase PLL structures," IEEE Trans. Ind. Electron., vol. 60, no. 6, pp. 2167-2177, Jun. 2013
    • (2013) IEEE Trans. Ind. Electron , vol.60 , Issue.6 , pp. 2167-2177
    • Golestan, S.1    Monfared, M.2    Freijedo, F.D.3    Guerrero, J.M.4
  • 22
    • 0033686420 scopus 로고    scopus 로고
    • A phase tracking system for three phase utility interface inverters
    • May
    • S. K. Chung, "A phase tracking system for three phase utility interface inverters," IEEE Trans. Power Electron., vol. 15, no. 3, pp. 431-438, May 2000
    • (2000) IEEE Trans. Power Electron , vol.15 , Issue.3 , pp. 431-438
    • Chung, S.K.1
  • 23
    • 0035335905 scopus 로고    scopus 로고
    • Synchronisation methods for grid-connected voltage source converters
    • DOI 10.1049/ip-gtd:20010101
    • J. Svensson, "Synchronization methods for grid-connected voltage source converters," Proc. Inst. Elect. Eng.-Gener. Transm. Distrib., vol. 148, no. 3, pp. 229-235, May 2001 (Pubitemid 32527713)
    • (2001) IEE Proceedings: Generation, Transmission and Distribution , vol.148 , Issue.3 , pp. 229-235
    • Svensson, J.1
  • 24
    • 0036529545 scopus 로고    scopus 로고
    • A nonlinear adaptive filter for online signal analysis in power systems: Applications
    • DOI 10.1109/61.997949, PII S0885897702027279
    • M. Karimi-Ghartemani and M. R. Iravani, "A nonlinear adaptive filter for online signal analysis in power systems applications," IEEE Trans. Power Del., vol. 17, no. 2, pp. 617-622, Apr. 2002 (Pubitemid 34684578)
    • (2002) IEEE Transactions on Power Delivery , vol.17 , Issue.2 , pp. 617-622
    • Karimi-Ghartemani, M.1    Iravani, M.R.2
  • 25
    • 4043161934 scopus 로고    scopus 로고
    • A method for synchronization of power electronic converters in polluted and variable-frequency environments
    • Aug
    • M. Karimi-Ghartemani and M. R. Iravani, "A method for synchronization of power electronic converters in polluted and variable-frequency environments," IEEE Trans. Power Syst., vol. 19, no. 3, pp. 1263-1270, Aug. 2004
    • (2004) IEEE Trans. Power Syst , vol.19 , Issue.3 , pp. 1263-1270
    • Karimi-Ghartemani, M.1    Iravani, M.R.2
  • 26
    • 1942519710 scopus 로고    scopus 로고
    • A magnitude phase-locked loop system based on estimation of frequency and in-phase quadrature-phase amplitudes
    • Apr
    • M. Karimi-Ghartemani, H. Karimi, and M. R. Iravani, "A magnitude phase-locked loop system based on estimation of frequency and in-phase quadrature-phase amplitudes," IEEE Trans. Ind. Electron., vol. 51, no. 2, pp. 511-517, Apr. 2004
    • (2004) IEEE Trans. Ind. Electron , vol.51 , Issue.2 , pp. 511-517
    • Karimi-Ghartemani, M.1    Karimi, H.2    Iravani, M.R.3
  • 27
    • 81855206519 scopus 로고    scopus 로고
    • Comparison of two methods for addressing DC component in phaselocked loop (PLL) systems
    • M. Karimi-Ghartemani, S. A. Khajehoddin, P. Jain, and A. Bakhshai, "Comparison of two methods for addressing DC component in phaselocked loop (PLL) systems," in Proc. ECCE, 2011, pp. 3053-3058
    • (2011) Proc. ECCE , pp. 3053-3058
    • Karimi-Ghartemani, M.1    Khajehoddin, S.A.2    Jain, P.3    Bakhshai, A.4
  • 28
    • 1942440026 scopus 로고    scopus 로고
    • Estimation of frequency and its rate of change for applications in power systems
    • Apr
    • H. Karimi, M. Karimi-Ghartemani, and M. R. Iravani, "Estimation of frequency and its rate of change for applications in power systems," IEEE Trans. Power Del., vol. 19, no. 2, pp. 472-480, Apr. 2004
    • (2004) IEEE Trans. Power Del , vol.19 , Issue.2 , pp. 472-480
    • Karimi, H.1    Karimi-Ghartemani, M.2    Iravani, M.R.3
  • 29
    • 77950966119 scopus 로고    scopus 로고
    • A three-phase adaptive notch filter-based approach to harmonic/reactive current extraction and harmonic decomposition
    • Apr.
    • D. Yazdani, A. Bakhshai, and P. K. Jain, "A three-phase adaptive notch filter-based approach to harmonic/reactive current extraction and harmonic decomposition," IEEE Trans. Power Electron., vol. 25, no. 4, pp. 914-923, Apr. 2010
    • (2010) IEEE Trans. Power Electron , vol.25 , Issue.4 , pp. 914-923
    • Yazdani, D.1    Bakhshai, A.2    Jain, P.K.3
  • 30
    • 85008050349 scopus 로고    scopus 로고
    • Tuning of phase-locked loops for power converters under distorted utility conditions
    • Nov./Dec
    • F. D. Freijedo, J. Doval-Gandoy, O. López, and E. Acha, "Tuning of phase-locked loops for power converters under distorted utility conditions," IEEE Trans. Ind. Appl., vol. 45, no. 6, pp. 2039-2047, Nov./Dec. 2009
    • (2009) IEEE Trans. Ind. Appl , vol.45 , Issue.6 , pp. 2039-2047
    • Freijedo, F.D.1    Doval-Gandoy, J.2    López, O.3    Acha, E.4
  • 31
    • 81855173476 scopus 로고    scopus 로고
    • A review on fundamental grid-voltage detection methods under highly distorted conditions in distributed power-generation networks
    • N. Hoffmann, R. Lohde, M. Fischer, F. W. Fuchs, L. Asiminoaei, and P. B. Thogersen, "A review on fundamental grid-voltage detection methods under highly distorted conditions in distributed power-generation networks," in Proc. IEEE ECCE, 2011, pp. 3045-3052
    • (2011) Proc IEEE ECCE , pp. 3045-3052
    • Hoffmann, N.1    Lohde, R.2    Fischer, M.3    Fuchs, F.W.4    Asiminoaei, L.5    Thogersen, P.B.6
  • 32
    • 80051722732 scopus 로고    scopus 로고
    • Frequency-adaptive stationary-reference-frame grid voltage sequence detector for distributed generation systems
    • Sep.
    • E. Robles, J. Pou, S. Ceballos, J. Zaragoza, J. L. Martin, and P. Ibañez, "Frequency-adaptive stationary-reference-frame grid voltage sequence detector for distributed generation systems," IEEE Trans. Ind. Electron., vol. 58, no. 9, pp. 4275-4287, Sep. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.9 , pp. 4275-4287
    • Robles, E.1    Pou, J.2    Ceballos, S.3    Zaragoza, J.4    Martin, J.L.5    Ibañez, P.6
  • 33
    • 44349189350 scopus 로고    scopus 로고
    • A robust phase-locked loop algorithm to synchronize static-power converters with polluted AC systems
    • DOI 10.1109/TIE.2008.918638
    • M. A. Perez, J. R. Espinoza, L. A. Moran, M. A. Torres, and E. A. Araya, "A robust phase-locked loop algorithm to synchronize staticpower converters with polluted AC systems," IEEE Trans. Ind. Electron., vol. 55, no. 5, pp. 2185-2192, May 2008 (Pubitemid 351728769)
    • (2008) IEEE Transactions on Industrial Electronics , vol.55 , Issue.5 , pp. 2185-2192
    • Perez, M.A.1    Espinoza, J.R.2    Moran, L.A.3    Torres, M.A.4    Araya, E.A.5
  • 34
    • 84857427775 scopus 로고    scopus 로고
    • An adaptive synchronous-reference-frame phase-locked loop for power quality improvement in a polluted utility grid
    • Jun.
    • F. Gonzalez-Espin, E. Figueres, and G. Garcera, "An adaptive synchronous-reference-frame phase-locked loop for power quality improvement in a polluted utility grid," IEEE Trans. Ind. Electron., vol. 59, no. 6, pp. 2718-2731, Jun. 2012
    • (2012) IEEE Trans. Ind. Electron , vol.59 , Issue.6 , pp. 2718-2731
    • Gonzalez-Espin, F.1    Figueres, E.2    Garcera, G.3
  • 35
    • 79960345850 scopus 로고    scopus 로고
    • Analysis and design of a digital phase-locked loop for single-phase grid-connected power conversion systems
    • Aug.
    • Z. Qi, S. Xiang-Dong, Z. Yan-Ru, M. Matsui, and B.-Y. Ren, "Analysis and design of a digital phase-locked loop for single-phase grid-connected power conversion systems," IEEE Trans. Ind. Electron., vol. 58, no. 8, pp. 3581-3592, Aug. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.8 , pp. 3581-3592
    • Qi, Z.1    Xiang-Dong, S.2    Yan-Ru, Z.3    Matsui, M.4    Ren, B.-Y.5
  • 36
    • 79956290432 scopus 로고    scopus 로고
    • Phase-locked loop noise reduction via phase detector implementation for single-phase systems
    • Jun.
    • T. Thacker, D. Boroyevich, R. Burgos, and F. Wang, "Phase-locked loop noise reduction via phase detector implementation for single-phase systems," IEEE Trans. Ind. Electron., vol. 58, no. 6, pp. 2482-2490, Jun. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.6 , pp. 2482-2490
    • Thacker, T.1    Boroyevich, D.2    Burgos, R.3    Wang, F.4
  • 37
    • 42449083729 scopus 로고    scopus 로고
    • A new single-phase PLL structure based on second order generalized integrator
    • Jun
    • M. Ciobotaru, R. Teodorescu, and F. Blaabjerg, "A new single-phase PLL structure based on second order generalized integrator," in Proc. IEEE PESC, Jun. 2006, pp. 1-6
    • (2006) Proc IEEE PESC , pp. 1-6
    • Ciobotaru, M.1    Teodorescu, R.2    Blaabjerg, F.3
  • 40
    • 0036506145 scopus 로고    scopus 로고
    • Stationary-frame generalized integrators for current control of active power filters with zero steady-state error for current harmonics of concern under unbalanced and distorted operating conditions
    • DOI 10.1109/28.993175, PII S009399940202666X
    • X. Yuan, W. Merk, H. Stemmler, and J. Allmeling, "Stationary-frame generalized integrators for current control of active power filters with zero steady-state error for current harmonics of concern under unbalanced and distorted operating conditions," IEEE Trans. Ind. Appl., vol. 38, no. 2, pp. 523-532, Mar./Apr. 2002 (Pubitemid 34491533)
    • (2002) IEEE Transactions on Industry Applications , vol.38 , Issue.2 , pp. 523-532
    • Yuan, X.1    Merk, W.2    Stemmler, H.3    Allmeling, J.4
  • 41
    • 85015505986 scopus 로고    scopus 로고
    • New positive-sequence voltage detector for grid synchronization of power converters under faulty grid conditions
    • P. Rodriguez, R. Teodorescu, I. Candela, A. V. Timbus, and F. Blaabjerg, "New positive-sequence voltage detector for grid synchronization of power converters under faulty grid conditions," in Proc. IEEE PESC, 2005, pp. 2474-2481
    • (2005) Proc IEEE PESC , pp. 2474-2481
    • Rodriguez, P.1    Teodorescu, R.2    Candela, I.3    Timbus, A.V.4    Blaabjerg, F.5
  • 42
    • 77953258964 scopus 로고    scopus 로고
    • Accurate and less-disturbing active anti-islanding method based on PLL for grid-connected converters
    • Jun.
    • M. Ciobotaru, V. G. Agelidis, R. Teodorescu, and F. Blaabjerg, "Accurate and less-disturbing active anti-islanding method based on PLL for grid-connected converters," IEEE Trans. Power Electron., vol. 25, no. 6, pp. 1576-1584, Jun. 2010
    • (2010) IEEE Trans. Power Electron , vol.25 , Issue.6 , pp. 1576-1584
    • Ciobotaru, M.1    Agelidis, V.G.2    Teodorescu, R.3    Blaabjerg, F.4
  • 43
    • 77956588764 scopus 로고    scopus 로고
    • Monitoring and synchronization techniques for single-phase PV systems
    • A. Nagliero, R. A. Mastromauro, M. Liserre, and A. Dell'Aquilla, "Monitoring and synchronization techniques for single-phase PV systems," in Proc. SPEEDAM, 2010, pp. 1404-1409
    • (2010) Proc. SPEEDAM , pp. 1404-1409
    • Nagliero, A.1    Mastromauro, R.A.2    Liserre, M.3    Dell'Aquilla, A.4
  • 44
    • 78650381218 scopus 로고    scopus 로고
    • Comparison and evaluation of the PLL techniques for the design of the grid-connected inverter systems
    • A. Nicastri and A. Nagliero, "Comparison and evaluation of the PLL techniques for the design of the grid-connected inverter systems," in Proc. ISIE, Jul. 2010, pp. 3865-3870
    • (2010) Proc. ISIE, Jul. , pp. 3865-3870
    • Nicastri, A.1    Nagliero, A.2
  • 45
    • 50249106454 scopus 로고    scopus 로고
    • Advanced grid synchronization system for power converters under unbalanced and distorted operating conditions
    • P. Rodriguez, A. Luna, M. Ciobotaru, R. Teodorescu, and F. Blaabjerg, "Advanced grid synchronization system for power converters under unbalanced and distorted operating conditions," in Proc. IECON, 2006, pp. 5173-5178
    • (2006) Proc. IECON , pp. 5173-5178
    • Rodriguez, P.1    Luna, A.2    Ciobotaru, M.3    Teodorescu, R.4    Blaabjerg, F.5
  • 46
    • 78650208824 scopus 로고    scopus 로고
    • Multiresonant frequency-locked loop for grid synchronization of power converters under distorted grid conditions
    • Jan.
    • P. Rodriguez, A. Luna, I. Candela, R. Mujal, R. Teodorescu, and F. Blaabjerg, "Multiresonant frequency-locked loop for grid synchronization of power converters under distorted grid conditions," IEEE Trans. Ind. Electron., vol. 58, no. 1, pp. 127-138, Jan. 2011
    • (2011) IEEE Trans. Ind. Electron , vol.58 , Issue.1 , pp. 127-138
    • Rodriguez, P.1    Luna, A.2    Candela, I.3    Mujal, R.4    Teodorescu, R.5    Blaabjerg, F.6
  • 51
    • 0035481879 scopus 로고    scopus 로고
    • Assessment of voltage unbalance
    • DOI 10.1109/61.956770, PII S0885897701070741
    • A. von Jouanne and B. Banerjee, "Assessment of voltage unbalance," IEEE Trans. Power Del., vol. 16, no. 4, pp. 782-790, Oct. 2001 (Pubitemid 33048006)
    • (2001) IEEE Transactions on Power Delivery , vol.16 , Issue.4 , pp. 782-790
    • Von Jouanne, A.1    Banerjee, B.2


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