Hierarchical control for parallel bidirectional power converters of a grid-connected DC microgrid

  • Hui-yong Hu
  • Yong-gang Peng
  • Yang-hong Xia
  • Xiao-ming Wang
  • Wei Wei
  • Miao Yu


The DC microgrid is connected to the AC utility by parallel bidirectional power converters (BPCs) to import/export large power, whose control directly affects the performance of the grid-connected DC microgrid. Much work has focused on the hierarchical control of the DC, AC, and hybrid microgrids, but little has considered the hierarchical control of multiple parallel BPCs that directly connect the DC microgrid to the AC utility. In this paper, we propose a hierarchical control for parallel BPCs of a grid-connected DC microgrid. To suppress the potential zero-sequence circulating current in the AC side among the parallel BPCs and realize feedback linearization of the voltage control, a d-q-0 control scheme instead of a conventional d-q control scheme is proposed in the inner current loop, and the square of the DC voltage is adopted in the inner voltage loop. DC side droop control is applied to realize DC current sharing among multiple BPCs at the primary control level, and this induces DC bus voltage deviation. The quantified relationship between the current sharing error and DC voltage deviation is derived, indicating that there is a trade-off between the DC voltage deviation and current sharing error. To eliminate the current sharing error and DC voltage deviation simultaneously, slope-adjusting and voltage-shifting approaches are adopted at the secondary control level. The proposed tertiary control realizes precise active and reactive power exchange through parallel BPCs for economical operation. The proposed hierarchical control is applied for parallel BPCs of a grid-connected DC microgrid and can operate coordinately with the control for controllable/uncontrollable distributional generation. The effectiveness of the proposed control method is verified by corresponding simulation tests based on Matlab/Simulink, and the performance of the hierarchical control is evaluated for practical applications.

Key words

Parallel bidirectional power converters Hierarchical control DC microgrid 

CLC number



Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anand, S., Fernandes, B.G., Guerrero, J., 2013. Distributed control to ensure proportional load sharing and improve voltage regulation in low-voltage DC microgrids. IEEE Trans. Power Electron., 28(4):1900–1913. https://doi.org/10.1109/TPEL.2012.2215055CrossRefGoogle Scholar
  2. Bao, J.Y., Bao, W.B., Zhang, Z.C., 2010. Generalized multilevel current source inverter topology with selfbalancing current. J. Zhejiang Univ.-Sci. C (Comput. & Electron.), 11(7):555–561. https://doi.org/10.1631/jzus.C0910605CrossRefGoogle Scholar
  3. Bao, X.W., Zhuo, F., Tian, Y., et al., 2013. Simplified feedback linearization control of three-phase photovoltaic inverter with an LCL filter. IEEE Trans. Power Electron., 28(6):2739–2752. https://doi.org/10.1109/TPEL.2012.2225076CrossRefGoogle Scholar
  4. Bidram, A., Davoudi, A., Lewis, F.L., et al., 2013. Distributed cooperative secondary control of microgrids using feedback linearization. IEEE Trans. Power Syst., 28(3):3462–3470. https://doi.org/10.1109/TPWRS.2013.2247071CrossRefGoogle Scholar
  5. Blasko, V., Kaura, V., 1997. A novel control to actively damp resonance in input LC filter of a three-phase voltage source converter. IEEE Trans. Ind. Appl., 33(2):542–550. https://doi.org/10.1109/28.568021CrossRefGoogle Scholar
  6. Che, L., Shahidehpour, M., Alabdulwahab, A., et al., 2015. Hierarchical coordination of a community microgrid with AC and DC microgrids. IEEE Trans. Smart Grid, 6(6):3042–3051. https://doi.org/10.1109/TSG.2015.2398853CrossRefGoogle Scholar
  7. Chen, T.P., 2012. Zero-sequence circulating current reduction method for parallel HEPWM inverters between AC bus and DC bus. IEEE Trans. Ind. Electron., 59(1):290–300. https://doi.org/10.1109/TIE.2011.2106102CrossRefGoogle Scholar
  8. Dragičević, T., Lu, X.N., Vasquez, J.C., et al., 2016. DC microgrids-part I: A review of control strategies and stabilization techniques. IEEE Trans. Power Electron., 31(7):4876–4891. https://doi.org/10.1109/TPEL.2015.2478859Google Scholar
  9. Eto, J., Lasseter, R., Schenkman, B., et al., 2009. Overview of the CERTS microgrid laboratory test bed. IEEE Trans. Power Del., 26(1):325–332. https://doi.org/10.1109/TPWRD.2010.2051819Google Scholar
  10. Gao, M.Z., Chen, M., Jin, C., et al., 2013. Analysis, design, and experimental evaluation of power calculation in digital droop-controlled parallel microgrid inverters. J. Zhejiang Univ.-Sci. C (Comput. & Electron.), 14(1):50–64. https://doi.org/10.1631/jzus.C1200236CrossRefGoogle Scholar
  11. Guerrero, J.M., Vasquez, J.C., Matas, J., et al., 2011. Hierarchical control of droop-controlled AC and DC microgrids—a general approach toward standardization. IEEE Trans. Ind. Electron., 58(1):158–172. https://doi.org/10.1109/TIE.2010.2066534CrossRefGoogle Scholar
  12. Guo, T.T., Liu, X.L., Hao, S.Q., et al., 2015. Analysis and design of pulse frequency modulation dielectric barrier discharge for low power applications. Front. Inform. Technol. Electron. Eng., 16(3):249–258. https://doi.org/10.1631/FITEE.1400185CrossRefGoogle Scholar
  13. Khorsandi, A., Ashourloo, M., Mokhtari, H., 2014. A decentralized control method for a low-voltage DC microgrid. IEEE Trans. Energy Conv., 29(4):793–801. https://doi.org/10.1109/TEC.2014.2329236CrossRefGoogle Scholar
  14. Lasseter, R., Akhil, A., Marnay, C., et al., 2002. Consortium for Electric Reliability Technology Solutions. White Paper on Integration of Distributed Energy Resources. The CERTS MicroGrid Concept, p.1–29.CrossRefGoogle Scholar
  15. Lee, T.S., 2003. Input-output linearization and zero-dynamics control of three-phase AC/DC voltage-source converters. IEEE Trans. Power Electron., 18(1):11–22. https://doi.org/10.1109/TPEL.2002.807145CrossRefGoogle Scholar
  16. Loh, P.C., Li, D., Chai, Y.K., et al., 2013. Autonomous control of interlinking converter with energy storage in hybrid AC-DC microgrid. IEEE Trans. Ind. Appl., 49(3):1374–1382. https://doi.org/10.1109/TIA.2013.2252319CrossRefGoogle Scholar
  17. Lu, X.N., Guerrero, J.M., Sun, K., et al., 2014a. Hierarchical control of parallel AC-DC converter interfaces for hybrid microgrids. IEEE Trans. Smart Grid, 5(2):683–692. https://doi.org/10.1109/TSG.2013.2272327CrossRefGoogle Scholar
  18. Lu, X.N., Guerrero, J.M., Sun, K., et al., 2014b. An improved droop control method for DC microgrids based on low bandwidth communication with DC bus voltage restoration and enhanced current sharing accuracy. IEEE Trans. Power Electron., 29(4):1800–1812. https://doi.org/10.1109/TPEL.2013.2266419CrossRefGoogle Scholar
  19. Meng, L.X., Dragicevic, T., Vasquez, J.C., et al., 2015. Tertiary and secondary control levels for efficiency optimization and system damping in droop controlled DC-DC converters. IEEE Trans. Smart Grid, 6(6):2615–2626 https://doi.org/10.1109/TSG.2015.2435055CrossRefGoogle Scholar
  20. Nasirian, V., Davoudi, A., Lewis, F.L., et al., 2014. Distributed adaptive droop control for DC distribution systems. IEEE Trans. Energy Conv., 29(4):944–956. https://doi.org/10.1109/TEC.2014.2350458CrossRefGoogle Scholar
  21. Nasirian, V., Moayedi, S., Davoudi, A., et al., 2015. Distributed cooperative control of DC microgrids. IEEE Trans. Power Electron., 30(4):2288–2303. https://doi.org/10.1109/TPEL.2014.2324579CrossRefGoogle Scholar
  22. Pan, C.T., Liao, Y.H., 2008. Modeling and control of circulating currents for parallel three-phase boost rectifiers with different load sharing. IEEE Trans. Ind. Electron., 55(7):2776–2785. https://doi.org/10.1109/TIE.2008.925647CrossRefGoogle Scholar
  23. Shafiee, Q., Dragičević, T., Vasquez, J.C., et al., 2014. Hierarchical control for multiple DC-microgrids clusters. IEEE Trans. Energy Conv., 29(4):922–933. https://doi.org/10.1109/TEC.2014.2362191CrossRefGoogle Scholar
  24. Torreglosa, J.P., García-Triviño, P., Fernández-Ramirez, L.M., et al., 2016. Control strategies for DC networks: a systematic literature review. Renew. Sust. Energy Rev., 58:319–330. https://doi.org/10.1016/j.rser.2015.12.314CrossRefGoogle Scholar
  25. Unamuno, E., Barrena, J.A., 2015. Hybrid ac/dc microgrids—Part II: review and classification of control strategies. Renew. Sustain. Energy Rev., 52:1123–1134. https://doi.org/10.1016/j.rser.2015.07.186CrossRefGoogle Scholar
  26. Wang, L.J., Yang, T., Zhang, D.M., et al., 2012. A high performance simulation methodology for multilevel gridconnected inverters. J. Zhejiang Univ.-Sci. C (Comput. & Electron.), 13(7):544–551. https://doi.org/10.1631/jzus.C1100315CrossRefGoogle Scholar
  27. Wang, P.B., Lu, X.N., Yang, X., et al., 2016. An improved distributed secondary control method for DC microgrids with enhanced dynamic current sharing performance. IEEE Trans. Power Electron., 31(9):6658–6673. https://doi.org/10.1109/TPEL.2015.2499310CrossRefGoogle Scholar
  28. Xiao, H.G., Luo, A., Shuai, Z.K., et al., 2016. An improved control method for multiple bidirectional power converters in hybrid AC/DC microgrid. IEEE Trans. Smart Grid, 7(1):340–347. https://doi.org/10.1109/TSG.2015.2469758CrossRefGoogle Scholar
  29. Xiao, J.F., Wang, P., Setyawan, L., 2016. Multilevel energy management system for hybridization of energy storages in DC microgrids. IEEE Trans. Smart Grid, 7(2):847–856. https://doi.org/10.1109/TSG.2015.2424983Google Scholar
  30. Xu, L., Chen, D., 2011. Control and operation of a DC microgrid with variable generation and energy storage. IEEE Trans. Power Del., 26(4):2513–2522. https://doi.org/10.1109/TPWRD.2011.2158456CrossRefGoogle Scholar
  31. Ye, Z.H., Boroyevich, D., Choi, J.Y., et al., 2002. Control of circulating current in two parallel three-phase boost rectifiers. IEEE Trans. Power Electron., 17(5):609–615. https://doi.org/10.1109/TPEL.2002.802170CrossRefGoogle Scholar
  32. Zhang, D., Wang, F.F., Burgos, R., et al., 2011. Common-mode circulating current control of paralleled interleaved threephase two-level voltage-source converters with discontinuous space-vector modulation. IEEE Trans. Power Electron., 26(12):3925–3935. https://doi.org/10.1109/TPEL.2011.2131681CrossRefGoogle Scholar

Copyright information

© Zhejiang University and Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  1. 1.College of Electrical EngineeringZhejiang UniversityHangzhouChina

Personalised recommendations