DOI QR코드

DOI QR Code

An Enhanced Power Sharing Strategy for Islanded Microgrids Considering Impedance Matching for Both Real and Reactive Power

  • Lin, Liaoyuan (College of Electrical Engineering, Zhejiang University) ;
  • Guo, Qian (College of Mechanical and Electrical Engineering, China Jiliang University) ;
  • Bai, Zhihong (College of Electrical Engineering, Zhejiang University) ;
  • Ma, Hao (College of Electrical Engineering, Zhejiang University)
  • Received : 2016.05.29
  • Accepted : 2016.10.28
  • Published : 2017.01.20

Abstract

There exists a strong coupling between real and reactive power owing to the complex impedances in droop based islanded microgrids (MGs). The existing virtual impedance methods consider improvements of the impedance matching for sharing of the voltage controlled power (VCP) (reactive power for Q-V droop, and real power for P-V droop), which yields a 1-DOF (degree of freedom) tunable virtual impedance. However, a weak impedance matching for sharing of the frequency controlled power (FCP) (real power for $P-{\omega}$ droop, and reactive power for $Q-{\omega}$ droop) may result in FCP overshoots and even oscillations during load transients. This in turn results in VCP oscillations due to the strong coupling. In this paper, a 2-DOF tunable adaptive virtual impedance method considering impedance matching for both real and reactive power (IM-PQ) is proposed to improve the power sharing performance of MGs. The dynamic response is promoted by suppressing the coupled power oscillations and power overshoots while realizing accurate power sharing. In addition, the proposed power sharing controller has a better parametric adaptability. The stability and dynamic performances are analyzed with a small-signal state-space model. Simulation and experimental results are presented to investigate the validity of the proposed scheme.

Keywords

References

  1. J. Rocabert, A. Luna, F. Blaabjerge, and P. Rodriguez, "Control of power converters in AC microgrids," IEEE Trans. Power Electron., Vol. 27, No. 11, pp. 4734-4749, Nov. 2012. https://doi.org/10.1109/TPEL.2012.2199334
  2. S. M. Ashabani, Y. A. I. Mohamed, "New family of microgrid control and management strategies in smart distribution grids - Analysis, comparison and testing," IEEE Trans. Power Syst., Vol. 29, No. 5, pp. 2257-2269, Sep. 2014. https://doi.org/10.1109/TPWRS.2014.2306016
  3. 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. https://doi.org/10.1109/TIE.2010.2066534
  4. X. Wang, J. M. Guerrero, F. Blaabjerg, and Z. Chen, "A review of power electronics based microgrids," Journal of Power Electronics, Vol. 12, No. 1, pp. 181-192, Jan. 2012. https://doi.org/10.6113/JPE.2012.12.1.181
  5. C. K. Sao and P. W. Lehn, "Autonomous load sharing of voltage source converters," IEEE Trans. Power Del., Vol. 20, No. 2, pp. 1009-1016, Apr. 2005. https://doi.org/10.1109/TPWRD.2004.838638
  6. Q. C. Zhong, "Robust droop controller for accurate proportional load sharing among inverters operated in parallel," IEEE Trans. Ind. Electron., Vol. 60, No. 4, pp. 1281-1290, Apr. 2013. https://doi.org/10.1109/TIE.2011.2146221
  7. X. Zhang, J. Liu, Z. You, and T. Liu, "Study on the influence of distribution lines to parallel inverter systems adopting the droop control method," Journal of Power Electronics, Vol. 13, No. 4, pp. 701-711, Jul. 2013. https://doi.org/10.6113/JPE.2013.13.4.701
  8. C.-T. Lee, C.-C. Chu, and P.-T. Cheng, "A new droop control method for the autonomous operation of distributed energy resource interface converters," IEEE Trans. Power Electron., Vol. 28, No. 4, pp. 1980-1993, Apr. 2013. https://doi.org/10.1109/TPEL.2012.2205944
  9. Y. Zhu, F. Zhuo, F. Wang, B. Liu, R. Gou, and Y. Zhao, "A virtual impedance optimization method for reactive power sharing in networked microgrid," IEEE Trans. Power Electron., Vol. 31, No. 4, pp.2890-2904, Apr. 2016. https://doi.org/10.1109/TPEL.2015.2450360
  10. Y. Zhu, F. Zhou, F. Wang, B. Liu, and Y. Zhao, "A wireless load sharing strategy for islanded microgrid based on feeder current sensing," IEEE Trans. Power Electron.. Vol. 30, No. 12, pp. 6706-6719, Dec. 2015. https://doi.org/10.1109/TPEL.2014.2386851
  11. H. Han, Y. Sun, M. Su, and J. M. Guerrero, "An improved droop control strategy for reactive power sharing in islanded microgrid," IEEE Trans. Power Electron., Vol.30, No.6, pp. 3133-3141, Jun. 2015. https://doi.org/10.1109/TPEL.2014.2332181
  12. J. Schiffer, T. Seel, J. Raisch, and T. Sezi, "Voltage stability and reactive power sharing in inverter-based microgrids with consensus-based distributed voltage control," IEEE Trans. Control Syst. Tech., Vol. 24, No. 1, pp.96-109, Jan. 2016. https://doi.org/10.1109/TCST.2015.2420622
  13. J. W. Simpson-Porco, Q. Shafiee, F. Dorfler, J. C. Vasquez, J. M. Guerrero, and F. Bullo, "Secondary frequency and voltage control of islanded microgrids via distributed averaging," IEEE Trans. Ind. Electron., Vol. 62, No. 11, pp. 7025-7038, Nov. 2015. https://doi.org/10.1109/TIE.2015.2436879
  14. Q. Guo, H. Wu, L. Lin, Z. Bai, and H. Ma, "Secondary voltage control for reactive power sharing in an islanded microgrid," Journal of Power Electronics, Vol. 16, No. 1, pp. 329-339, Jan. 2016. https://doi.org/10.6113/JPE.2016.16.1.329
  15. Q. Shafiee, J. M. Guerrero, and J. C. Vasquez, "Distributed secondary control for islanded microgrids - A novel approach," IEEE Trans. Power Electron., Vol. 29, No. 2, pp. 1018-1031, Feb. 2014. https://doi.org/10.1109/TPEL.2013.2259506
  16. H. Mahmood, D. Michaelson, and J. Jiang, "Reactive power sharing in islanded microgrids using adaptive voltage droop control," IEEE Trans. Smart Grid, Vol. 6, No. 6, pp. 3052-3060, Nov. 2015. https://doi.org/10.1109/TSG.2015.2399232
  17. J. He and Y. W. Li, "An enhanced microgrid load demand sharing strategy," IEEE Trans. Power Electron., Vol. 27, No.9, pp. 3984-3995, Sep. 2012. https://doi.org/10.1109/TPEL.2012.2190099
  18. Y. Zhu, B. Liu, F. Wang, F. Zhuo, and Y. Zhao, "A virtual resistance based reactive power sharing strategy for networked microgrid," in Proc. IEEE ICPE-ECCE Asia, pp. 1564-1572, 2015.
  19. J. He, Y. W. Li, and F. Blaabjerg, "An enhanced islanding microgrid reactive power, imbalance power, and harmonic power sharing scheme," IEEE Trans. Power Electron., Vol. 30, No. 6, pp. 3389-3401, Jun. 2015. https://doi.org/10.1109/TPEL.2014.2332998
  20. H. Mahmood, D. Michaelson, and J. Jiang, "Accurate reactive power sharing in an islanded microgrid using adaptive virtual impedances," IEEE Trans. Power Electron., Vol. 30, No. 3, p. 1605-1617, Mar. 2015. https://doi.org/10.1109/TPEL.2014.2314721
  21. J. He,Y. W. Li , J. M. Guerrero, F. Blaabjerg, and J. C. Vasquez, "An islanding microgrid power sharing approach using enhanced virtual impedance control scheme," IEEE Trans. Power Electron., Vol. 28, No. 11, pp. 5272-5282, Nov. 2013. https://doi.org/10.1109/TPEL.2013.2243757
  22. J. M. Guerrero, L G de Vicuna, J. Matas, M. Castilla, and J. Miret, "Output impedance design of parallel-connected UPS inverters with wireless load-sharing control," IEEE Trans. Ind. Electron., Vol. 52, No.4, pp. 1126-1135, Aug. 2005. https://doi.org/10.1109/TIE.2005.851634
  23. J. M. Guerrero, J. Matas, L G de Vicuna, M. Castilla, and J. Miret, "Wireless-control strategy for parallel operation of distributed-generation inverters," IEEE Trans. Ind. Electron., Vol. 53, No. 5, pp. 1461-1470, Oct. 2006. https://doi.org/10.1109/TIE.2006.882015
  24. J. M. Guerrero, J. Matas, L. G. de Vicuna, M. Castilla, and J. Miret, "Decentralized control for parallel operation of distributed generation inverters using resistive output impedance," IEEE Trans. Ind. Electron., Vol. 54, No. 2, pp. 994-1004, Apr. 2007. https://doi.org/10.1109/TIE.2007.892621
  25. W. Yao, M. Chen, 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. Ind. Electron., Vol. 58, No. 2, pp. 576-588, Feb. 2011. https://doi.org/10.1109/TIE.2010.2046001
  26. Q. C. Zhong and Y. Zeng, "Control of inverters via a virtual capacitor to achieve capacitive output impedance," IEEE Trans. Power Electron., Vol. 29, No. 10, pp. 5568-5578, Oct. 2014. https://doi.org/10.1109/TPEL.2013.2294425
  27. 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
  28. A. Kahrobaeian and Y. A. I. Mohamed, "Networked-Based Hybrid Distributed Power Sharing and Control for Islanded Microgrid Systems," IEEE Trans. Power Electron., Vol. 30, No. 2, pp. 603-617, Feb. 2015. https://doi.org/10.1109/TPEL.2014.2312425