Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
권호 표지
DOI QR코드

DOI QR Code

Stabilizing dc-link voltage and neutral point current fuctuation in grid-connected three-level NPC converter under generalized grid fault conditions

  • Jaehoon Choi (Department of Electrical Engineering SGRC, Jeonbuk National University) ;
  • Yongsug Suh (Department of Electrical Engineering SGRC, Jeonbuk National University)
  • Received : 2022.10.17
  • Accepted : 2023.01.16
  • Published : 2023.04.20
⟨ Previous Next ⟩

Abstract

This study introduces a stabilizing scheme that decreases the fuctuations in dc-link voltage and neutral point current in a grid-connected three-level NPC converter under generalized grid fault conditions. The fundamental component of the neutral point current is generated under grid-unbalanced conditions. Regardless of the type of unbalance in the grid, the behavior and pattern of the fundamental components of the neutral current are determined by the imbalance factor. The proposed control scheme, which involves regulating the negative sequence component of the ac input current, efectively reduces the size of the dc-link voltage ripple and the fundamental component of neutral point current under diverse types of grid unbalanced conditions. This is verifed by simulations and experiments under various conditions. The proposed control method will improve the stability and reliability of the grid-connected converter under various types of imbalance conditions.

Keywords

Acknowledgement

This research was supported by Korea Electric Power Corporation (KEPCO) (Grant number: R21XO01-6).

References

  1. Jung, K., Suh, Y.: Compensation of neutral point deviation under generalized 3-phase imbalance in 3-level NPC converters. J. Power Electron. 18(6), 1866-1878 (2018)
  2. Suh, Y., Go, Y., Roh, D.: A comparative study on control algorithm for active front-end rectifer of large motor drives under unbalanced input. IEEE Trans. Ind. Appl. 47(3), 1419-1431 (2011) https://doi.org/10.1109/TIA.2011.2126015
  3. Suh, Y.S., Tijeras, V., Lipo, T.A.: A control method in dq synchronous frame for PWM boost rectifer under generalized unbalanced operating conditions. IEEE Trans. Ind. Appl. 46(3), 825-835 (2006) https://doi.org/10.1109/TIA.2006.873673
  4. Jung, K., Suh, Y.: Analysis and control of neutral-point deviation in three-level NPC converter under unbalanced three-phase AC grid. IEEE Trans. Ind. Appl. 55(5), 4944 (2019)
  5. Suh, Y., Lipo, A.: Control scheme in hybrid synchronous stationary frame for PWM AC/DC converter under generalized unbalanced operating conditions. IEEE Trans. Ind. Appl. 42(3), 825-835 (2006) https://doi.org/10.1109/TIA.2006.873673
  6. Song, H.S., Nam, K.H.: Dual current control scheme for PWM converter under unbalanced input voltage conditions. IEEE Trans. Ind. Electron. 46(5), 953-959 (1999) https://doi.org/10.1109/41.793344
  7. Z Zhang, R Kennel, Direct Model Predictive Control of ThreeLevel NPC Back-to-Back Power Converter PMSG Wind Turbine Systems Under Unbalanced Grid. In Conf, IEEE PRECEDE, Valparaiso, Chile. pp. 97-102, Oct 2015
  8. Y. H. Yoo, N. J. Ku, D. S. Hyun, The control algorithm of threelevel NPC inverter under unbalanced input voltage conditions. In Conf, IEEE vehicle power and propulsion, Coimbra, Portugal. pp. 1-5, Oct 2014
  9. Wang, C., Li, Y.: Analysis and calculation of zero-sequence voltage considering neutral-point potential balancing in three-level NPC converter. IEEE Trans. Ind. Electron. 57(7), 2262-2271 (2010) https://doi.org/10.1109/TIE.2009.2024093
  10. Celanovic, N., Boroyevich, D.: A comprehensive study of neutral-point voltage balancing problem in three-level neutral-pointclamped voltage source PWM inverters. IEEE Trans. Power Electron. 15(2), 242-249 (2000) https://doi.org/10.1109/63.838096
  11. S. Ogasawara, and H. Akagi, Analysis of variation of neutral point potential in neutral-point-clamped voltage source PWM inverter. In Conf. Rec. IEEE IAS Annu. Meeting, 1993, pp. 965-970
  12. Y. Lai, Y. Chou, S. Pai, Simple PWM technique of capacitor voltage balance for three-level inverter with dc-link voltage sensor only. In Proc. 33rd Annu. Conf. IEEE IECON, 2007, pp. 1749-1754
  13. Holtz, J., Oikonomou, N.: Neutral point potential balancing method at low modulation index for three-level inverter medium voltage drives. IEEE Trans. Ind. Electron. 43(3), 761-768 (2007) https://doi.org/10.1109/TIA.2007.895767
  14. L. Jun, Q. H. Alex, Q. Zhaoming, Z. Huijie, A novel carrier-based PWM method for 3-level NPC inverter utilizing control freedom degree. In Proc. IEEE Power Electron. Spec. Conf., 2007, pp. 1899-1904.
  15. Rodriguez, P., Pou, J., Bergas, J., Candela, J. I., Burgos, R.P., Boroyevich, D.: Decoupled double synchronous reference frame PLL for power converters control. IEEE Trans. Power Electron. 22(2), 585 (2007)
  16. Dugan, R.C., Mcgranaghan, M.F., Santoso, S., Beaty, H.W.: Electrical Power Systems Quality, 2nd edn., pp. 53-55. Mcgraw-Hill Publishing Company, Inc, New York (2005)
  17. Leborgne, R. Voltage Sags Characterisation and Estimation. Master's thesis, Chalmers University of Technology, Goteborg, Sweden, Retrieved from http://www.publications.lib.chalmers.se/records/fulltext/9004.pdf, (2006). Accessed 30 May 2019
  18. Choi, J., Suh, Y.: Analysis and minimization of neutral point current deviation in grid tied 3-level npc converter under various grid fault conditions. In: 2020 IEEE energy conversion congress and exposition (ECCE), pp. 6192-6196. IEEE, New York (2020)
  19. J. Choi and Y. Suh, Analysis and control of neutral point current deviation in grid tied 3-level NPC converter under various grid unbalanced conditions. 2020 IEEE 9th International Power Electronics and Motion Control Conference (IPEMC2020-ECCE Asia). 2020, p. 710-716
  20. Choi, J., Suh, Y.: A control method of reduced reactive power ripple in grid-connected converters under unbalanced grid conditions. IPEC2022-ECCE Asia, New York (2022)