Document Type : Research Articles

Authors

1 Faculty of Electrical and Computer Engineering, University of Birjand, Birjand, Iran

2 University of Birjand

3 Department of Electrical Engineering -Center of Excellence for Power System Automation and Operation - Iran University of Science and Technology

Abstract

A hybrid AC-DC microgrid consists of an AC and a DC subgrid that are connected to each other through an interlinking converter (IC). The main function of an IC under islanded conditions is to transfer power between the two subgrids. In this paper, a scheme is presented to reduce the voltage unbalance factor in a hybrid AC-DC microgrid by using the free capacity of the IC. The free capacity of this converter is determined based on the current passing through each leg, and the amount of voltage unbalance compensation on the AC side of the microgrid is then obtained. The reference current of voltage unbalance compensation is calculated by using the positive, negative, and zero sequence components of the voltage of IC terminals. The total reference current is obtained by adding the reference current of voltage unbalance compensation and the current calculated for power transfer. Furthermore, a proportional-resonant (PR) controller is used in the control system of the four-leg inverter. Therefore, the reference current is properly tracked by the power stage of the inverter. Simulation results verify the accuracy of the proposed scheme under different conditions.

Keywords

Main Subjects

[1] IEEE Guide for Design, Operation, and Integration of
Distributed Resource Island Systems with Electric Power
Systems, IEEE Std. 1547.4-2011,, 2011.

[2] T. Vigneysh, N. Kumarappan, and R. Arulraj, Operation
and control of wind/fuel cell based hybrid microgrid in grid
connected mode, Automation, Computing,
Communication, Control and Compressed Sensing
(iMac4s), 2013 International Multi-Conference on, pp.
754-758, 2013.

[3] R. Noroozian and G. B. Gharehpetian, “Combined
operation of converter‐based distributed generation unit in
DC distribution system in order to have premium power
quality,” European Transactions on Electrical Power, vol.
22, no. 4, pp. 449-470, 2012.

[4] Q. Shafiee, J. M. Guerrero, and J. C. Vasquez, “Distributed
secondary control for islanded microgridsA novel
approach,” IEEE Transactions on power electronics, vol.
29, no. 2, pp. 1018-1031, 2014.

[5] Y. Jafarian, A. Karimi, and H. Bevrani, “Secondary Voltage
Control in a Hybrid Microgrid,” International Journal of
Industrial Electronics, Control and Optimization, vol. 2, no.
3, pp. 221-232, 2019.

[6] H. Karimi, H. Nikkhajoei, and R. Iravani, “Control of an
electronically-coupled distributed resource unit subsequent
to an islanding event,” IEEE Transactions on Power
Delivery, vol. 23, no. 1, pp. 493-501, 2008.

[7] B. Kroposki, R. Lasseter, T. Ise, S. Morozumi, S.
Papathanassiou, and N. Hatziargyriou, “Making microgrids
work,” IEEE Power and Energy Magazine, vol. 6, no. 3, pp.
40-53, 2008.

[8] J. M. Guerrero, J. C. Vasquez, J. Matas, L. G. De Vicuña,
and M. Castilla, “Hierarchical control of droop-controlled
AC and DC microgridsA general approach toward
standardization,” IEEE Transactions on Industrial
Electronics, vol. 58, no. 1, pp. 158-172, 2011.

[9] S. Bahramirad, W. Reder, and A. Khodaei,
“Reliability-constrained optimal sizing of energy storage
system in a microgrid,” IEEE Transactions on Smart Grid,
vol. 3, no. 4, pp. 2056-2062, 2012.

[10] A. Gupta, S. Doolla, and K. Chatterjee, “Hybrid ACDC
microgrid: systematic evaluation of control strategies,”
IEEE Transactions on Smart Grid, vol. 9, no. 4, pp.
3830-3843, 2018.

[11] P. C. Loh, D. Li, Y. K. Chai, and F. Blaabjerg, “Hybrid AC
DC microgrids with energy storages and progressive energy
flow tuning,” IEEE transactions on power electronics, vol.
28, no. 4, pp. 1533-1543, 2013.

[12] X. Liu, P. Wang, and P. C. Loh, “A hybrid AC/DC
microgrid and its coordination control,” IEEE Transactions
on Smart Grid, vol. 2, no. 2, pp. 278-286, 2011.

[13] F. Nejabatkhah and Y. W. Li, “Overview of power
management strategies of hybrid AC/DC microgrid,” IEEE
Transactions on Power Electronics, vol. 30, no. 12, pp.
7072-7089, 2015.

[14] P. C. Loh, D. Li, Y. K. Chai, and F. Blaabjerg,
“Autonomous operation of ac-dc microgrids with
minimised interlinking energy flow,” IET Power
Electronics, vol. 6, no. 8, pp. 1650-1657, 2013.

[15] R. Ghanizadeh, M. Ebadian, and G. B. Gharehpetian, “Non‐
linear load sharing and voltage harmonics compensation in
islanded microgrids with converter interfaced units,”
International Transactions on Electrical Energy Systems,
vol. 27, no. 1, pp. e2237, 2017.

[16] E. Fuchs and M. A. Masoum, Power quality in power
systems and electrical machines: Academic press, 2011.

[17] B. Nanda and R. Jena, “Power Quality Analysis by using
Active Filter in AC/DC Microgrid,” International Journal
of Scientific Research in Science and Technology (IJSRST),
vol. 4, no. 9, pp. 47-56, 2018.

[18] L. F. Monteiro, M. Aredes, C. Couto, and J. L. Afonso,
“Control algorithms for a unified power quality conditioner
based on three‐level converters,” International
Transactions on Electrical Energy Systems, vol. 25, no. 10,
pp. 2394-2411, 2015.

[19] T. XiangQian, X. Keqing, S. Ming, and M. Xianhong,
"Reactive power and unbalance compensation with
DSTATCOM," International Conference on Electrical
Machines and Systems, pp. 1181-1184, 2005.

[20] F. Nejabatkhah, Y. W. Li, and B. Wu, “Control strategies of
three-phase distributed generation inverters for grid
unbalanced voltage compensation,” IEEE Transactions on
Power Electronics, vol. 31, no. 7, pp. 5228-5241, 2016.

[21] M. Savaghebi, A. Jalilian, J. C. Vasquez, and J. M.
Guerrero, “Autonomous voltage unbalance compensation in
an islanded droop-controlled microgrid,” IEEE
Transactions on Industrial Electronics, vol. 60, no. 4, pp.
1390-1402, 2012.

[22] L. Meng, X. Zhao, F. Tang, M. Savaghebi, T. Dragicevic, J.
C. Vasquez, et al., “Distributed voltage unbalance
compensation in islanded microgrids by using a dynamic
consensus algorithm,” IEEE Transactions on Power
Electronics, vol. 31, no. 1, pp. 827-838, 2015.

[23] S. D. Dehnavi and E. Shayani, “Compensation of Voltage
disturbances in hybrid AC/DC Microgrids using series
converter,” Ciência e Natura, vol. 37, no. 2, pp. 349-356,
2015.

[24] P. G. Khorasani, M. Joorabian, and S. G. Seifosadat, “A
new proposal for the design of hybrid AC/DC microgrids
toward high power quality,” Turkish Journal of Electrical
Engineering & Computer Sciences, vol. 25, no. 5, pp.
4033-4049, 2017.

[25] K. Sun, X. Wang, Y. W. Li, F. Nejabatkhah, Y. Mei, and X.
Lu, “Parallel operation of bidirectional interfacing
converters in a hybrid AC/DC microgrid under unbalanced
grid voltage conditions,” IEEE Transactions on Power
Electronics, vol. 32, no. 3, pp. 1872-1884, 2016.

[26] F. Nejabatkhah, Y. W. Li, K. Sun, and R. Zhang, “Active
power oscillation cancelation with peak current sharing in
parallel interfacing converters under unbalanced voltage,”
IEEE Transactions on Power Electronics, vol. 33, no. 12,
pp. 10200-10214, 2018.

[27] P. C. Loh, D. Li, Y. K. Chai, and F. Blaabjerg,
“Autonomous control of interlinking converter with energy
storage in hybrid ACDC microgrid,” IEEE Transactions
on Industry Applications, vol. 49, no. 3, pp. 1374-1382,
2013.

[28] P. Wang, C. Jin, D. Zhu, Y. Tang, P. C. Loh, and F. H.
Choo, “Distributed control for autonomous operation of a
three-port AC/DC/DS hybrid microgrid,” IEEE
Transactions on Industrial Electronics, vol. 62, no. 2, pp.
1279-1290, 2015.

[29] J. M. Guerrero, J. C. Vasquez, J. Matas, M. Castilla, and L.
G. de Vicuña, “Control strategy for flexible microgrid based
on parallel line-interactive UPS systems,” IEEE
Transactions on Industrial Electronics, vol. 56, no. 3, pp.
726-736, 2009.

[30] J. Zhang, D. Guo, F. Wang, Y. Zuo, and H. Zhang, Control
strategy of interlinking converter in hybrid AC/DC
microgrid, International Conference on Renewable Energy
Research and Applications (ICRERA), pp. 97-102, 2013.

[31] P. C. Loh, D. Li, Y. K. Chai, and F. Blaabjerg,
“Autonomous operation of hybrid microgrid with AC and
DC subgrids,” IEEE transactions on power electronics, vol.
28, no. 5, pp. 2214-2223, 2012.

[32] IEEE standard definitions for the measurement of electric
power quantities under sinusoidal, nonsinusoidal,
balanced, or unbalanced conditions, IEEE Std. 1459-2010,
2010.

[33] B. Johansson, Improved models for DC-DC converters,
Dept. Ind. Electr. Eng. Autom., Lund University, sweden,
2003.

[34] P. A. F. Galarza, Stationary frame control of three-leg and
four-leg voltage source inverters in power system
applications: Modelling and simulations, M.S. Thesis, The
University of Nottingham, 2016.

[35] D. G. Holmes, T. A. Lipo, B. P. Mcgrath, and W. Y. Kong,
“Optimized design of stationary frame three phase AC
current regulators,” IEEE transactions on power
electronics, vol. 24, no. 11, pp. 2417-2426, 2009.

[36] S. H. Tabatabaei, M. M. BAJESTAN, and A. Jalilian,
“Shunt active power filter control for compensating current
power quality problems in three-phase three-wire systems
based on an adaptive notch filter,” Turkish Journal of
Electrical Engineering & Computer Sciences, vol. 24, no. 4,
pp. 2539-2555, 2016.

[37] A. Bergen and V. Vittal, Power systems analysis, Prentice
Hall, 2000.

[38] D. Yazdani, M. Mojiri, A. Bakhshai, and G. Joós, “A fast
and accurate synchronization technique for extraction of
symmetrical components,” IEEE Transactions on Power
Electronics, vol. 24, no. 3, pp. 674-684, 2009.