Document Type : Research Articles

Authors

1 Department of Electrical Engineering, University of Kurdistan, Sanandaj, Iran.

2 Department of Electrical Engineering, University of Kurdistan, Sanandaj, Iran

Abstract

In this paper, a virtual inertia control strategy based on linear feedback is presented that improves dynamic behavior of islanded dc microgrids interfaced with constant power loads (CPLs). In order to solve the stability challenges caused by low inertia and CPLs, the proposed control scheme is composed of a virtual capacitor and a virtual conductance. It is implemented in the inner loop control, i.e. current loop control to be fast enough emulating inertia and damping concept. In addition, the droop characteristic is modeled by using the virtual resistance which adjusts the steady-state response of the system. In this study a multi-level structure is considered, which comprises the source level, interface converter level, and common load level. In addition, an accurate small-signal model is used to investigate the stability of dc MG interlaced with CPLs, and then, an acceptable range of inertia response parameters is determined by using the root locus analysis. Performance of the proposed control structure is demonstrated through numerical simulations.

Keywords

Main Subjects

[1] H. Bevrani, B. Francois, T. Ise, Microgrid Dynamics and
Control, NJ, USA: Wiley, July 2017.

[2] H. Bevrani, M. Watanabe, Y. Mitani, Power System
Monitoring and Control. Hoboken, NJ, USA: IEEE-Wiley,
Jun. 2014.

[
3] U. Tamrakar, D. Shrestha, M. Maharjan, B. P. Bhattarai, T.
M. Hansen, R. Tonkoski,
Virtual inertia: Current trends and
future directions,
Appl. Sci., vol. 7, no. 7, pp. 654, Jun. 2017.

[4] S. Wei, Y. Zhou, and Y. Huang, Synchronous Motor-
Generator Pair to Enhance Small Signal and Transient
Stability of Power System with High Penetration of
Renewable Energy, IEEE Access, vol. 5, pp. 11505-11512,
Jun. 2017.

[5] N. Soni, S. Doolla, M. C. Chandorkar, Improvement of
transient response in microgrids using virtual inertia, IEEE
Trans. Power Del., vol. 28, no. 3, pp. 1830-1838 Jul. 2013.

[6] E. Rakhshani, P. Rodriguez, “Inertia emulation in ac/dc
interconnected power systems using derivative technique
considering frequency measurement effects,” IEEE Trans.
Power Syst., vol. 32, no. 5, pp. 33383351, Sep. 2017.

[
7] H. Bevrani, T. Ise, Y. Miura, Virtual synchronous
generators: A survey and new perspectives,
Int. J. Elect.
Power Energy Syst.
, vol. 54, pp. 244-254, Jan. 2014.

[
8] M. Ebrahimi, SA. Khajehoddin, MK. Ghartemani, An
improved damping method for virtual synchronous

machines
,” IEEE Trans. Sustainable Energy, vol. 10, no. 3,
pp. 1491
-1500, Jul. 2019.

[9] A. Karimipouya, S. Karimi, H. Abdi, Microgrid frequency
control using the virtual inertia and ANFIS-based controller,
International Journal of Industrial Electronics, Control and
Optimization, vol. 2, no. 2, pp. 145-154, Apr. 2019.

[
10] M. Guan, W. Pan, J. Zhang, Q. Hao, J. Cheng, X. Zheng,
Synchronous generator emulation control strategy for voltage source converter (VSC) stations, IEEE Trans.
Power Syst.
, vol. 30, no. 6, pp. 3093-3101, Nov. 2015.

[
11] C. Li, J. Xu, C. Zhao, A coherency-based equivalence
method for MMC inverters using virtual synchronous

generator control,
IEEE Trans. Power Del., vol. 31, no. 3,
pp. 1369
-1378, Jun. 2016.

[12] X. Meng, J. Liu, Z. Liu, “A generalized droop control for
grid-supporting inverter based on comparison between
traditional droop control and virtual synchronous generator
control,” IEEE Trans. Power Electron., pp. 1-1, Sep. 2018.

[
13] Y.P. Kumar, R. Bhimasingu, “Fuzzy logic based adaptive
virtual inertia in droop control operation of the microgrid for

improved transient response,”
Asia-Pacific Power and
Energy Engineering Conf. (APPEEC)
, 2017, pp. 1-6.

[
14] A. Karimi, Y. Jafarian, H. Bevrani, R. Mirzaei, Frequency
response improvement in microgrids: a fuzzy
based virtual
synchronous generator approach
, International Journal of
Industrial Electronics, Control and Optimization
, vol. 3, no.
2, pp.147
-158, Apr. 2020.

[
15] A. Fathi, Q. Shafiee, H. Bevrani, Robust frequency control
of microgrids using an
extended virtual synchronous
generator
,” IEEE Trans. Power Syst., vol. 33, no. 6, pp. 6289-
6297, Nov. 2018.

[16] W. Wu, Y. Chen, A. Luo, L. Zhou, X. Zhou, L. Yang, Y.
Dong, J. M. Guerrero, “A virtual inertia control strategy for
dc microgrids analogized with virtual synchronous
machines,” IEEE Trans. Ind. Electron., vol. 64, no. 7, pp.
60056016, Jul. 2017.

[
17] Z. Yi, X. Zhao, D. Shi, J. Duan, Y. Xiang, Z. Wang,
Accurate power sharing and synthetic inertia control for dc
building microgrids with guaranteed performance
,” IEEE
Access
, vol. 7, no. 7, pp. 63698-708, May. 2019.

[
18] W. Im, C. Wang, W. Liu, L. Liu, J. Kim, Distributed virtual
inertia based control of mutiple photovoltaic
systems in
autonomous microgrid
,” IEEE/CAA J.Autom. Sinica, vol. 4,
no. 3, pp. 512
-519, Jul. 2017.

[19] J. B. Zhu, C. D. Booth, G. P. Adam, A. J. Roscoe, C. G.
Bright, “Inertia emulation control strategy for VSC-HVDC
transmission systems,” IEEE Tran. Power Syst., vol. 28, no.
2, pp. 1277-1287, May. 2013.

[20] A. Hosseinipour, H. Hojabri, Virtual inertia control of PV
systems for dynamic performance and damping enhancement
of dc microgrids with constant power loads, IET Renew.
Power Gener., vol.12, no.4, pp.430-438, 2017.

[
21] S. Samanta, J. P. Mishra, B. K. Roy, Virtual dc machine: an
inertia emulation and control
technique for a bidirectional
dc
dc converter in a dc microgrid,” IET Electr. Power Appl.,
vol.
12, no. 6, pp. 874-884, Mar. 2018.

[
22] L. Herrera, W. Zhang, J. Wang, Stability analysis and
controller design of DC microgrids with constant power

loads
,” IEEE Trans. Smart Grid, vol. 8, no. 2, pp. 881-888,
Aug. 2015.

[
23] M. Su, Z. Liu, Y. Sun, H. Han, X. Hou, Stability analysis
and stabilization m
ethods of DC microgrid with multiple
parallel
-connected DCDC converters loaded by
CPLs
,” IEEE Trans. Smart Grid, vol. 9, no. 1, pp.132-142,
Mar. 2016
.

[
24] M. Cespedes, X. Lei, S. Jian, Constant-power load system
stabilization by passive damping
,” IEEE Trans. Power
Electron.
, vol. 26, no. 7, pp. 1832-1836, Jul. 2011.
[
25] J. Liu, W. Zhang, G. Rizzoni, Robust stability analysis of
DC microgrids with constant power loads
,” IEEE Trans.
Power Syst
., vol. 33, no. 1, pp. 851-860, Apr. 2017.
[26] S. Arora, P. Balsara, D. Bhatia, InputOutput Linearization
of a Boost Converter With Mixed Load (Constant Voltage

Load and Constant Power Load)
,” IEEE Trans. Power
Electron
., vol. 34, no. 1, pp. 815-825, Jan. 2019.

[
27] Q. Xu,C. Zhang, C. Wen, P. Wang, A novel composite
nonlinear
controller for stabilization of constant power load
in DC microgrid,
IEEE Trans. Smart Grid, vol. 10, no. 1,
pp. 752
-761, Sep. 2017.

[28] M. Su, Z. Liu, Y. Sun, H. Han, X. Hou, Stability analysis
and stabilization methods of dc microgrid with multiple
parallel-connected dc-dc converters loaded by CPLs, IEEE
Trans. Smart Grid, vol.9, no.1, pp.132-142, 2018.

[
29] K. A. Potty, E. Bauer, H. Li, J. Wang, Smart resistor:
stabilization of dc microgrids containing constant power

loads using high
-bandwidth power converters and energy
storage
, IEEE Trans. Power Electron., vol. 35, no. 1,
pp.957
-967, Jan. 2020.

[30] M. Wu, D. D. C. Lu, a novel stabilization method of LC
input filter with constant power loads without load
performance compromise in dc microgrids, IEEE Trans.
Ind. Electron., vol. 62, no. 7, pp. 4552-4562, July 2015.

[
31] M. N. Hussain, R. Mishra, V. Agarwal, A frequency-
dependent virtual impedance for voltage
-regulating
converters feeding constant power loads in a dc

microgrid",
IEEE Trans. Ind. Appl., vol. 54, no. 6, pp. 5630-
5639, Nov./Dec. 2018.

[
32] S. Liu, P. Su, L. Zhang, A virtual negative inductor
stabilizing strategy for dc microgrid with constant power

loads
, IEEE Access, vol. 6, pp. 59728-59741, 2018.

[
33] X. Lu, K. Sun, J.M. Guerrero, J.C. Vasquez, L. Huang, J.
Wang,
Stability enhancement based on virtual impedance
for dc microgrids with constant power
loads, IEEE Trans.
Smart Grid
, vol. 6, no. 6, pp. 2770-2783, Jun. 2015.

[34] R. W. Erickson, D. Maksimovic, Fundamentals of power
electronics. Springer Science & Business Media, 2007.