The Transactions of the Korean Institute of Power Electronics (전력전자학회논문지)

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

DOI QR Code

Droop Method for High-Capacity Parallel Inverters in Islanded Mode Using Virtual Inductor

독립운전 모드에서 가상 인덕터를 활용한 대용량 인버터 병렬운전을 위한 드룹제어

  • Jung, Kyo-Sun (School of Electrical Eng., Chungbuk National University) ;
  • Lim, Kyung-Bae (School of Electrical Eng., Chungbuk National University) ;
  • Kim, Dong-Hwan (School of Electrical Eng., Chungbuk National University) ;
  • Choi, Jaeho (School of Electrical Eng., Chungbuk National University)
  • Received : 2014.09.18
  • Accepted : 2014.12.22
  • Published : 2015.02.20
Download PDF
⟨ Previous Next ⟩

Abstract

This paper investigates the droop control-based real and reactive power load sharing with a virtual inductor when the line impedance between inverter and Point of Common Coupling (PCC) is partly and unequally resistive in high-capacity systems. In this paper, the virtual inductor method is applied to parallel inverter systems with resistive and inductive line impedance. Reactive power sharing error has been improved by applying droop control after considering each line impedance voltage drop. However, in high capacity parallel systems with large output current, the reference output voltage, which is the output of droop controller, becomes lower than the rated value because of the high voltage drop from virtual inductance. Hence, line impedance voltage drop has been added to the droop equation so that parallel inverters operate within the range of rated output voltage. Additionally, the virtual inductor value has been selected via small signal modeling to analyze stability in transient conditions. Finally, the proposed droop method has been verified by MATLAB and PSIM simulation.

Keywords

References

  1. J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galvan, R. C. P. guosado, M. A. M. Prats, J. I. Leon, and N. Moreno-Alfonso, "Power-electronic systems for the grid integration of renewable energy sources: A survey," IEEE Trans. on Power Electron., Vol. 53, No. 4, pp. 1002-1016, Jun. 2006.
  2. F. Z. Peng, Y. W. Li, and L. M. Tolbert, "Control and protection of power electronics interfaced distributed generation systems in a customer-driven microgrid," in Proc. IEEE Power Eng. Soc. Gen. Meet., pp. 1-8, Jul. 2009.
  3. H. L. Jou, W. J. Chiang, and J. C. Wu, "A simplified control method for the grid-connected inverter with the function of islanding detection," IEEE Trans. on Power Electron., Vol. 23, No. 6, pp. 2775-2783, Nov. 2008. https://doi.org/10.1109/TPEL.2008.2003015
  4. W. Yao, M. Chen, J. Matas, J. M. Guerrero, and Z. M. Qian, "Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing," IEEE Trans. on Ind. Electron., Vol. 58, No 2, pp. 576-588, Feb. 2011. https://doi.org/10.1109/TIE.2010.2046001
  5. A. Tuladhar, H. Jin, T. Unger, and K. Mauch, "Parallel operation for single phase inverter modules with no control interconnections," in Conf. of Rec. IEEE APEC, pp. 94-100, Feb. 1997.
  6. K. S. Parlak, M. Ozdemir, and M. T. Aydemir, "Active and reactive power sharing and frequency restoration in a distributed power system consisting of two UPS units," Electrical Power and Energy System, Vol. 31, No. 5, pp. 220-226, Jun. 2009. https://doi.org/10.1016/j.ijepes.2009.01.006
  7. Y. W. Li and C. N. Kao, "An accurate power control strategy for power-electronics-interfaced distributed generation units operation in a low voltage multibus microgrid," IEEE Trans. on Power Electron., Vol. 24, No. 12, pp. 2977-2988, Dec. 2009. https://doi.org/10.1109/TPEL.2009.2022828
  8. K. D. Brabandere, B. Bolsens, J. V. Keybus, A. Woyte, J. Driesen, and R. A. Belmans, "A voltage and frequency droop control method for parallel inverters," IEEE Trans. on Power Electron., Vol. 22, No. 4, pp. 1107-1115, Jul. 2007. https://doi.org/10.1109/TPEL.2007.900456
  9. J. M. Gurrero, L. G. Vicuna, J. Matas, M. Castilla, and J. Miret, "A wireless controller to enhance dynamic performance of parallel inverters in distributed generation systems," IEEE Trans. on Power Electron., Vol. 19, No. 5, pp. 1205-1213, Sep. 2004. https://doi.org/10.1109/TPEL.2004.833451
  10. J. M. Gurrero, L. G. Vicuna, J. Matas, M. Castilla, and J. Miret, "Output impedance design of parallelconnected UPS inverters with wireless load-sharing control," IEEE Trans. on Ind. Electron., Vol. 52, No. 4, pp. 1126-1135, Aug. 2005. https://doi.org/10.1109/TIE.2005.851634
  11. J. He and Y. W. Li, "Anaysis, design, and implementation of virtual impedance for power electronics interfaced distributed generation," IEEE Trans. Ind. Appl., Vol. 47, No. 6, pp. 2525-2538, Nov. 2011. https://doi.org/10.1109/TIA.2011.2168592
  12. K. B. Lim and J. H. Choi, "Droop Control for Parallel Inverters in Islanded Microgrid Considering Unbalanced Low-Voltage Line Impedance," Transactions of Korean Institute of Power Electronics, Vol. 18, No. 4, pp. 387-396, Aug. 2013. https://doi.org/10.6113/TKPE.2013.18.4.387
  13. N. Pogaku, M. Prodanovic, and T. C. Green, "Modeling, analysis and testing of autonomous operation of an inverter-based microgrid," IEEE Trans. on Power Electron., Vol. 22, No. 2, pp 613-625, Mar. 2007 https://doi.org/10.1109/TPEL.2006.890003
  14. Z. Guo, D. Sha, and X. Liao, "Wireless paralleled control strategy of three-phase inverter modules for islanding distributed generation systems," Journal of Power Electronics, Vol. 13, No. 3, pp. 479-486, May 2013. https://doi.org/10.6113/JPE.2013.13.3.479
  15. Q. C. Zhong and Y. Zeng, "Can the output impedance of an inverter be designed capacitive?," in Conf. of Rec. IECON, pp. 1220-1225, Nov. 2011.
  16. Q. C. Zhong and Y. Zeng, "Control of inverters via a virtual capacitor to achieve capacitive output impedance," IEEE Trans. on Power Electron., Vol. 29, No. 10, pp. 5568-5578, Oct. 2014. https://doi.org/10.1109/TPEL.2013.2294425
  17. Y. Chen, A. Luo, J. Zhou, L. Bai, and C. Tu, "Rapid reactive power control method for parallel inverters using resistive-capacitive output impedance," in Conf. of Rec. IFEEC, pp. 98-102, Nov. 2013.
  18. C. K. Sao and P. W. Lehn, "Autonomous load sharing of voltage source converters," IEEE Trans. on Power Delivery., Vol. 20, No. 2, pp. 1009-1016, Apr. 2005. https://doi.org/10.1109/TPWRD.2004.838638
  19. Y. A. I. Mohamed and E. F. El-Saadany, "Adaptive decentralized droop controller to preserve power sharing stability of parallel inverters in distributed generation microgrid," IEEE Trans. on Power Electron., Vol. 23, No. 6, pp. 2806-2816, Nov. 2008. https://doi.org/10.1109/TPEL.2008.2005100
  20. G. F. Franklin, J. D. Powell, and A. Emami-Naeini, Feedback control of dynamic systems (6th ed.), Prentice-Hall, 2010.
  21. H. S. Kim, S. C. Shin, H. J. Lee, C. H. Jung, D. W. Han, and C. Y. Won, "Control Method for Reducing Circulating Current in Parallel Operation of DC Distribution System for Building Applications," Transactions of Korean Institute of Power Electronics, Vol. 18, No. 3, pp. 256-262, Jun. 2013. https://doi.org/10.6113/TKPE.2013.18.3.256
  22. U. K. Jo, J. S. Yim, and S. K. Sul, "A Study on Parallel Operation of PWM Inverters for High Speed and High Power Motor Drive System," Transactions of Korean Institute of Power Electronics, Vol. 15, No. 3, pp. 244-251, Jun. 2010. https://doi.org/10.6113/TKPE.2010.15.3.244