Hierarchical Control for Accurate Power Sharing and Circulation Current Reduction in Resistive AC Microgrids Using Adaptive Virtual Impedance and Distributed Communication Links
Subject Areas : electrical and computer engineeringMasoud Esmaili 1 , Mohammad Hejri 2 *
1 -
2 - Sahand University of Technology
Keywords: Virtual impedance, power sharing, circulating current, droop controller, hierarchical control,
Abstract :
This paper presents an efficient method based on the adaptive virtual impedance and distributed communication link with a hierarchical control system in the resistive AC islanding micrigrids for accurate power sharing and circulating current reduction. In existing methods, the adaptive virtual resistance can take negative values and violate the assumption of feeders’ resistive dominance based on which the droop controller is designed, and as a result, deteriorate its performance. Besides, the negative virtual resistance, with a reduction in the system overall damping, can reduce the stability margin and lead to side effects on the closed-loop system performance, especially during transients. In the proposed method, the problems associated with the negative virtual resistance are removed via the intelligent implementation of a new distributed communication link among microgrid inverters. The advantages of the proposed method include: circulating current elimination, accurate power sharing among distributed generators proportional to their rated capacities, prevention of voltage and frequency deviations from their reference values in point of power coupling (PCC) bus, guarantee of the resistive or inductive dominance of the feeder impedance in various operating points, decoupling between active and reactive powers, and as a result, guarantee of a desirable performance for droop controller in different operating points, performance and stability improvement, and finally using a simple, one-sided and a low bandwidth communication link instead of the complex, two-sided, and centralized communication system. Simulation results in MATLAB/SIMULINK environment demonstrate that the proposed control strategy has obviated effectively the shortcomings of the conventional droop and adaptive virtual impedance controllers.
[1] X. Huang, Z. Wang, and J. Jiang, "Control and load-dispatching strategies for a microgrid with a DC/AC inverter of fixed frequency," International J. of Electrical Power and Energy System, vol. 43, no. 1, pp. 1127-1136, Dec. 2012.
[2] H. Han, X. Hou, J. Yang, J. Wu, M. Su, and J. M. Guerrero, "Review of power sharing control strategies for islanding operation of AC microgrids," IEEE Trans. on Smart Grid, vol. 7, no. 1, pp. 200-215, Jun. 2015.
[3] A. Mohd, E. Ortjohann, D. Morton, and O. Omari, "Review of control techniques for inverters parallel operation," Electric Power Systems Research, vol. 80, no. 12, pp. 1477-1487, Dec. 2010.
[4] T. L. Vandoom, J. D. M. De Kooning, B. Meersman, J. M. Guerrero, and L. Vandevelde, "Automatic power-sharing modification of P/V droop controllers in low-voltage resistive microgrids," IEEE Trans. on Power Delivery, vol. 27, no. 4, pp. 2318-2325, Oct. 2012.
[5] Y. Han, H. Li, P. Shen, E. A. A. Coelho, and J. M. Guerrero, "Review of active and reactive power sharing strategies in hierarchical controlled microgrids," IEEE Trans. on Power Electronics, vol. 32, no. 3, pp. 2427-2451, Mar. 2017.
[6] 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. on Industrial Electronics, vol. 52, no. 4, pp. 1126-1135, Aug. 2005.
[7] 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. on Industrial Electronics, vol. 54, no. 2, pp. 994-1004, Apr. 2007.
[8] 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. on Power Electronics, vol. 28, no. 11, pp. 5272-5282, Nov. 2013.
[9] J. He, Y. W. Li, J. M. Guerrero, J. C. Vasquez, and F. Blaabjerg, "An islanding microgrid reactive power sharing scheme enhanced by programmed virtual impedances," in Proc. 3rd IEEE Int. Symp. on Power Electronics for Distributed Generation System, pp. 229-235, alborg, Denmark, 25-28 Jun. 2012.
[10] L. Asiminoaei, R. Teodorescu, F. Blaabjerg, and U. Borup, "A digital controlled PV-inverter with grid impedance estimation for ENS detection," IEEE Trans. on Power Electronics, vol. 20, no. 6, pp. 1480-1490, Nov. 2005.
[11] S. Huang and J. Luo, "Accurate power sharing in proportion for parallel connected inverters by reconstructing inverter output impedance," J. on Power Electronics, vol. 18, no. 6, pp. 1751-1759, Nov. 2018.
[12] Q. Guo, et al., "Secondary voltage control for reactive power sharing in an islanded microgrid," J. of Power Electronics, Korean Institute of Power Electronics, vol. 16, no. 1, pp. 329-339, Jan. 2016.
[13] M. Hamzeh, H. Karimi, H. Mokhtari, and M. Popov, "An accurate power sharing method for control of a multi-DG microgrid," in Proc. Int. Conf. on Power Systems Transients, 6, pp., Delft, The Netherlands, 14-17 Jun. 2011.
[14] X. H. T. Pham and T. T. Le, "Control strategy for accurate reactive power sharing in islanded microgrids," J. of Power Electronics, vol. 19, no. 4, pp. 1020-1033, Jul. 2019.
[15] Y. W. Li and C. N. Kao, "An accurate power control strategy for power-electronics-interfaced distributed generation units operating in a low-voltage multibus microgrid," IEEE Trans. on Power Electronics, vol. 24, no. 12, pp. 2977-2988, Dec. 2009.
[16] H. Mahmood, D. Michaelson, and J. Jiang, "Reactive power sharing in islanded microgrids using adaptive voltage droop control," IEEE Trans. on Smart Grid, vol. 6, no. 6, pp. 3052-3060, Nov. 2015.
[17] ب. فانی، م. معظمی و ع. فرهودی، "کاهش هامونیکهای ولتاژ با استفاده از کنترلکننده افتی در عملکرد موازی اینورترها،" نشریه مهندسی برق و مهندسی کامپیوتر ایران، الف- مهندسی برق، سال 17، شماره 2، صص. 107-97، تابستان 1398.
[18] M. Savaghebi, A. Jalilian, J. C. Vasquez, and J. M. Guerrero, "Secondary control for voltage quality enhancement in microgrids," IEEE Trans. on Smart Grid, vol. 3, no. 4, pp. 1893-1902, Dec. 2012.
[19] M. Zhang, Z. Du, X. Lin, and J. Chen, "Control strategy design and parameter selection for suppressing circulating current among SSTs in parallel," IEEE Trans. on Smart Grid, vol. 6, no. 4, pp. 1602-1609, Jul. 2015.
[20] H. Mahmood, D. Michaelson, and J. Jiang, "Accurate reactive power sharing in an islanded microgrid using adaptive virtual impedances," IEEE Trans. on Power Electronics, vol. 30, no. 3, pp. 1605-1617, Mar. 2015.
[21] M. Pham and H. Lee, "Effective coordinated virtual impedance control for accurate power sharing in islanded microgrid," IEEE Trans. on Industrial Electronics, vol. 20, no. 14, pp. 125-135, Jul. 2020.
[22] B. Wei, A. Marzabal, R. Ruiz, J. M. Guerrero, and J. C. Vasquez, "DAVIC: a new distributed adaptive virtual impedance control for parallel-connected voltage source inverters in modular UPS system," IEEE Trans. on Power Electronics, vol. 34, no. 6, pp. 5953-5968, Jun. 2019.
[23] X. Liang, C. Andalib-Bin-Karim, W. Li, M. Mitolo, and M. N. S. K. Shabbir, "Adaptive virtual impedance-based reactive power sharing in virtual synchronous generator controlled microgrids," IEEE Trans. on Industry Applications, vol. 57, no. 1, pp. 46-60, Jan./Feb. 2021.
[24] A. S. Vijay, N. Parth, S. Doolla, and M. C. Chandorkar, "An adaptive virtual impedance control for improving power sharing among inverters in islanded AC microgrids," IEEE Trans. on Smart Grid, vol. 12, no. 4, pp. 2991-3003, Jul. 2021.
[25] B. Liu, Z. Liu, J. Liu, R. An, H. Zheng, and Y. Shi, "An adaptive virtual impedance control scheme based on Small-AC-Signal injection for unbalanced and harmonic power sharing in islanded microgrids," IEEE Trans. on Power Electronics, vol. 34, no. 12, pp. 12333-12355, Dec. 2019.
[26] Z. Chen, X. Pei, M. Yang, and L. Peng, "An adaptive virtual resistor (AVR) control strategy for low-voltage parallel inverters," IEEE Trans. on Power Electronics, vol. 34, no. 1, pp. 863-867, Jan. 2019.
[27] Y. X. Zhu, F. Zhuo, F. Wang, B. Q. Liu, and Y. J. 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.
[28] M. Eskandari and L. Li, "Microgrid operation improvement by adaptive virtual impedance," IET Renewable Power Generation, vol. 13, no. 2, pp. 296-307, Feb. 2019.
[29] X. Chen, C. Zhang, Q. Huang, and M. Ofori-Oduro, "Small-signal modeling and analysis of grid-connected inverter with power differential droop control," Mathematical Problems in Engineering, vol. 2016, Article ID: 3965945, Jun. 2016.
[30] Y. Chen, J. M. Guerrero, Z. Shuai, Z. Chen, L. Zhou, and A. Luo, "Fast reactive power sharing, circulating current and resonance suppression for parallel inverters using resistive-capacitive output impedance," IEEE Trans. on Power Electronics, vol. 31, no. 8, pp. 5524-5537, Aug. 2016.
[31] J. M. Guerrero, et al., "Hierarchical control of droop-controlled AC and DC microgrids-a general approach toward standardization," IEEE Trans. on Industrial Electronics, vol. 58, no. 2, pp. 158-172, Jan. 2011.
[32] M. Zhang, B. Song, and J. Wang, "Circulating current control strategy based on equivalent feeder for parallel inverters in islanded microgrid," IEEE Trans. on Power Systems, vol. 34, no. 1, pp. 595-605, Jan. 2019.
[33] Q. Shafiee, J. M. Guerrero, and J. C. Vasquez, "Distributed secondary control for islanded microgrids-a novel approach," IEEE Trans. on Power Electronics, vol. 29, no. 2, pp. 1018-1031, Feb. 2014.
[34] M. B. Delghavi, Advanced Islanded-Mode Control of Microgrids, the University of Western Ontario, Oct. 2011.
[35] J. C. Vasquez, J. M. Guerrero, M. Savaghebi, J. E. Garcia, and R. Teodorescu, "Modeling, analysis, and design of stationary-reference-frame droop-controlled parallel three-phase voltage source inverters," IEEE Trans. on Industrial Electronics, vol. 60, no. 4, pp. 1271-1280, Apr. 2013.