IEEE Electrification Magazine - June 2016 - 70

TECHNOLOGY LEADERS

40-kW
Converter

100-A /400-V Shared Common Bus
Load

10×
4-kW
Module

Human safety, grounding, and
economic factors are all considerations that cannot be forgotten
when the ultimate solution to
protection within dc microgrids
is pursued.

10-A /400-V Dedicated Bus

Load

4-kW
Module

Load

4-kW
Module

Load

4-kW
Module

Load

Figure 6. A one-on-one dedicated converter-load power distribution architecture using the powerlimiting and self-protection capability of the power converter to provide circuit fault protection.

4-kW
Module
4-kW
Module

3× 10-A Bus

30-A
Load

4-kW
Module

10-A Bus

Load

Figure 7. A large power source can be designed as a cluster of smaller modular power
converters connected in parallel via O-ring diodes. Each modular power converter supplies
power to the common load with a designated power cable.

providing power to one load via a
designated power cable (Figure 7). The
power bus now changes from one
thick power cable to a bundle of insulated thinner wires, which may have
implications for cable cost and
weight, as well as the complexity of
connecting these wires. One additional benefit of this scheme is the
enhanced system redundancy for a
particular load if two or more of the
modular power source units are connected to the power cable through
O-ring diodes.
Of course, it may not always be
practical to implement this strategy
on every load in the microgrid. The

I E E E E l e c t r i f i c ati o n M agaz ine / J UN E 2016

following summary of approaches
should also be considered to
im prove the robustness of faultprotective strategies:
x autonomous SSCBs inserted
between dedicated source power
converters and loads
x networked, centrally controlled
smart SSCBs judiciously placed
at critical nodes of the system
to complement the protective
capabilities of power converters and autonomous SSCBs
x hybrid circuit breakers with
ultrafast contactors that can
carry sufficient current to aid in
arc extinction.

For Further Reading
Z. J. Shen, G. Sabui, Z. Miao, and Z. Shuai,
"Wide-bandgap solid-state circuit breakers for DC power systems: Device and
circuit considerations," IEEE Trans. Electron Devices, vol. 62, no. 2, pp. 294-300,
Jan. 2015.
Z. Miao, G. Sabui, A. Chen, Y. Li, Z.
J. Shen, J. Wang, Z. Shuai, A. Luo, X.
Yin , and M. Jiang , "A self-powered
ultra-fast DC solid state circuit breaker using a normally on SiC JFET," in
Proc. 30th Annu. IEEE Applied Power
Electronics Conf. and Exposition (APEC),
Charlotte, NC, 2015, pp. 767-773.
Z. J. Shen, Z. Miao , and A. M.
Roshandeh, "Solid state circuit breakers for DC microgrids: Current status
and future trends," in Proc. IEEE First Int.
Conf. DC Microgrids (ICDCM), Atlanta,
GA, 2015, pp. 228-233.
Y. Sato , Y. Tanaka , A. Fukui , M .
Yamasaki, and H. Ohashi, "SiC-SIT
circuit breakers with controllable
interruption voltage for 400-V DC distribution systems," IEEE Trans. Power
Electron., vol. 29, no. 5, pp. 2597-2605,
May 2013.
D. P. Urciuoli , V. Veliadis, H. C.
Ha, and V. Lubomirsky, "Demonstration of a 600-V, 60-A, bidirectional
silicon carbide solid-state circuit
breaker," in Proc. 26th Annu. IEEE
Applied Power Electronics Conf. and
Exposition (APEC), Fort Worth, TX,
2011, pp. 354-358.

Biography
Z. John Shen (johnshen@ieee.org)
is the Grainger Chair professor
of electrical and power engineering at Illinois Institute of Technology, Chicago. He is a Fellow of
the IEEE.

Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2016