An improved droop control algorithm for load sharing and circulating current control for parallel DC-DC converters in standalone DC microgrid

This paper discuss the relationship between load sharing and circulating current for parallel connected dc-dc converters. In the proposed algorithm a new figure-of-merit called Droop Index is introduced, which is a function of normalized current sharing difference and losses in the output side of the converters. This algorithm minimizes the circulating current and current sharing difference between the converters based on the virtual resistance, Rdroop values. This also eliminates the trade-off between current sharing difference and voltage regulation. By calculating negative Rdroop values, the algorithm gives better performance and low voltage regulation. The detailed analysis and design procedure are explained for two dc-dc boost converters connected in parallel. The effectiveness of proposed method is verified using MATLAB simulation.

[1]  Juan C. Vasquez,et al.  An Improved Droop Control Method for DC Microgrids Based on Low Bandwidth Communication With DC Bus Voltage Restoration and Enhanced Current Sharing Accuracy , 2014, IEEE Transactions on Power Electronics.

[2]  Mahesh K. Mishra,et al.  Circulating current minimization and current sharing control of parallel boost converters based on Droop Index , 2013, 2013 9th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics and Drives (SDEMPED).

[3]  C. Mullett,et al.  Seven ways to parallel a magamp , 1993, Proceedings Eighth Annual Applied Power Electronics Conference and Exposition,.

[4]  Federico Delfino,et al.  Optimal Control and Operation of Grid-Connected Photovoltaic Production Units for Voltage Support in Medium-Voltage Networks , 2014, IEEE Transactions on Sustainable Energy.

[5]  Richard Duke,et al.  DC-Bus Signaling: A Distributed Control Strategy for a Hybrid Renewable Nanogrid , 2006, IEEE Transactions on Industrial Electronics.

[6]  A. Sannino,et al.  An Adaptive Control System for a DC Microgrid for Data Centers , 2007, IEEE Transactions on Industry Applications.

[7]  Tamotsu Ninomiya,et al.  Load-current-sharing control for parallel operation of DC-to-DC converters , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[8]  R. Dougal,et al.  Robust nonlinear synergetic control for m-parallel-connected DC-DC boost converters , 2008, 2008 IEEE Power Electronics Specialists Conference.

[9]  Milan M. Jovanovic,et al.  Analysis, design, and performance evaluation of droop current-sharing method , 2000, APEC 2000. Fifteenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.00CH37058).

[10]  Issa Batarseh,et al.  Investigation of the output droop characteristics of parallel-connnected DC-DC converters , 1994, Proceedings of 1994 Power Electronics Specialist Conference - PESC'94.

[11]  Fred C. Lee,et al.  A classification and evaluation of paralleling methods for power supply modules , 1999, 30th Annual IEEE Power Electronics Specialists Conference. Record. (Cat. No.99CH36321).

[12]  H. Akagi,et al.  DC microgrid based distribution power generation system , 2004, The 4th International Power Electronics and Motion Control Conference, 2004. IPEMC 2004..

[13]  Frede Blaabjerg,et al.  Autonomous Operation of Hybrid Microgrid With AC and DC Subgrids , 2011, IEEE Transactions on Power Electronics.

[14]  S. R. Bull,et al.  Renewable energy today and tomorrow , 2001, Proc. IEEE.

[15]  Bo-Hyung Cho,et al.  A novel droop method for converter parallel operation , 2002 .

[16]  B. G. Fernandes,et al.  Distributed Control to Ensure Proportional Load Sharing and Improve Voltage Regulation in Low-Voltage DC Microgrids , 2013, IEEE Transactions on Power Electronics.

[17]  B Renders,et al.  A Control Strategy for Islanded Microgrids With DC-Link Voltage Control , 2011, IEEE Transactions on Power Delivery.

[18]  B. G. Fernandes,et al.  Modified droop controller for paralleling of dc-dc converters in standalone dc system , 2012 .

[19]  F. C. Lee,et al.  Modeling and dynamic analysis of paralleled DC/DC converters with master-slave current sharing control , 1996, Proceedings of Applied Power Electronics Conference. APEC '96.

[20]  Juan C. Vasquez,et al.  Hierarchical Control of Droop-Controlled AC and DC Microgrids—A General Approach Toward Standardization , 2009, IEEE Transactions on Industrial Electronics.