Design of Emotional Learning Controllers for AC Voltage and Circulating Current of Wind-Farm-Side Modular Multilevel Converters

  • Li, Keli (School of Electrical Engineering, Chongqing University) ;
  • Liao, Yong (School of Electrical Engineering, Chongqing University) ;
  • Liu, Ren (School of Electrical Engineering, Chongqing University) ;
  • Zhang, Jimiao (School of Electrical Engineering, Chongqing University)
  • Received : 2016.02.23
  • Accepted : 2016.06.21
  • Published : 2016.11.20


The introduction of a high-voltage direct-current (HVDC) system based on a modular multilevel converter (MMC) for wind farm integration has stimulated studies on methods to control this type of converter. This research article focuses on the control of the AC voltage and circulating current for a wind-farm-side MMC (WFS-MMC). After theoretical analysis, emotional learning (EL) controllers are proposed for the controls. The EL controllers are derived from the learning mechanisms of the amygdala and orbitofrontal cortex which make the WFS-MMC insensitive to variance in system parameters, power change, and fault in the grid. The d-axis and q-axis currents are respectively considered for the d-axis and q-axis voltage controls to improve the performance of AC voltage control. The practicability of the proposed control is verified under various conditions with a point-to-point MMC-HVDC system. Simulation results show that the proposed method is superior to the traditional proportional-integral controller.


Supported by : Scientific Research Foundation


  1. L. Wang and M. S. N. Thi, "Comparative stability analysis of offshore wind and marine-current farms feeding into a power grid using HVDC links and HVAC line," IEEE Trans. Power Del., Vol. 28, No. 4, pp. 2162-2171, Oct. 2013.
  2. J. L. Sawin, E. Martinot, D. Barnes, A. McCrone, J. Roussell, R. Sims, V. S. O'Brian, R. Adib, J. Skeen, E. Musolino, L. Riahi, and L. Mastny, "Renewables 2011: global status report," Renewable Energy Policy Network for the 21st Century, Vol. 46, No. 38, p. 116, 2011.
  3. "Global wind statistics 2014," GWEC, pp. 1-4, 2015.
  4. G.-D. Wang, R.-J. Wai, and Y. Liao, "Design of backstepping power control for grid-side converter of voltage source converter-based high-voltage dc wind power generation system," IET Renewable Power Generation, Vol. 7, No. 2, pp. 118-133, Mar. 2013.
  5. S. Cole and R. Belmans, "Transmission of bulk power," IEEE Ind. Electron. Mag. Vol. 3, No. 3, pp. 19-24, Sep. 2009.
  6. N. Flourentzou, V. G. Agelidis, and G. D. Demetriades, "VSC-based HVDC power transmission systems: an overview," IEEE Trans. Power Electron., Vol. 24, No. 3, pp. 592-602, Mar. 2009.
  7. J. Pan, R. Nuqui, K. Srivastava, T. Jonsson, P. Holmberg, and Y. J. Hafner, "AC grid with embedded VSC-HVDC for secure and efficient power delivery," in IEEE Energy 2030 Conference, pp. 1-6, Nov. 2008.
  8. R. E. Torres-Olguin, A. Garces, M. Molinas, and T. Undeland, "Integration of offshore wind farm using a hybrid HVDC transmission composed by the PWM current-source converter and line-commutated converter," IEEE Trans. Energy Convers., Vol. 28, No. 1, pp. 125-134, Mar. 2013.
  9. N. Ahmed, L. Angquist, S. Norrga, A. Antonopoulos, L. Harnefors, and H. P. Nee, "A computationally efficient continuous model for the modular multilevel converter," IEEE J. Emerg. Sel. Topics Power Electron., Vol. 2, No. 4, pp. 1139-1148, Dec. 2014.
  10. A. Lesnicar and R. Marquardt, "An innovative modular multilevel converter topology suitable for a wide power range," in IEEE Bologna Power Tech Conference Proceedings, pp. 1-6, Jun. 2003.
  11. B. Gemmell, J. Dorn, D. Retzmann, and D. Soerangr, "Prospects of multilevel VSC technologies for power transmission," in IEEE/PES Transmission and Distribution Conference and Exposition, pp. 1-16, Apr. 2008.
  12. S. Debnath, J. Qin, B. Bahrani, M. Saeedifard, and P. Barbosa, "Operation, control, and applications of the modular multilevel converter: a review," IEEE Trans. Power Electron., Vol. 30, No. 1, pp. 37-53, Jan. 2015.
  13. L. Xu, L. Yao, and C. Sasse, "Grid integration of large DFIG-based wind farms using VSC transmission," IEEE Trans. Power Syst., Vol. 22, No. 3, pp. 976-984, Aug. 2007.
  14. L. Guan, X. Fan, Y. Liu, and Q.H. Wu, "Dual-mode control of AC/VSC-HVDC hybrid transmission systems with wind power integrated," IEEE Trans. Power Del., Vol. 30, No. 4, pp. 1686-1693, Aug. 2015.
  15. Q. Tu, Z. Xu, and L. Xu, "Reduced switching-frequency modulation and circulating current suppression for modular multilevel converters," IEEE Trans. Power Del., Vol. 26, No. 3, pp. 2009-2017, Jul. 2011.
  16. S. Rohner, S. Bernet, M. Hiller, and R. Sommer, "Analysis and simulation of a 6 kV, 6 MVA modular multilevel converter," in 35th Annual Conference of IEEE Industrial Electronics, pp. 225-230, 2009.
  17. Q. Song, W. Liu, X. Li, H. Rao, S. Xu, and L. Li, "A steady-state analysis method for a modular multilevel converter," IEEE Trans. Power Electron., Vol. 28, No. 8, pp. 3702-3713, Aug. 2013.
  18. X. She, A. Huang, X. Ni, and R. Burgos, "AC circulating currents suppression in modular multilevel converter," in 38th Annual Conference on IEEE Industrial Electronics Society(IECON), pp. 191-196, Oct. 2012.
  19. J. Moren, Emotion and learning - a computational model of the amygdala, Ph.D. Dissertation, Lund University, Sweden, 2002.
  20. M. A. Rahman, R. M. Milasi, C. Lucas, B. N. Araabi, and T. S. Radwan, "Implementation of emotional controller for interior permanent-magnet synchronous motor drive," IEEE Trans. Ind. Appl., Vol. 44, No. 5, pp. 1466-1476, Sep./Oct. 2008.
  21. S. M. Kay, "Fundamentals of statistical signal processing," Prentice Hall PTR, Chapter 2, pp. 19-20, 1993.