	US 12,456,858 B2
	Systems and a method for fault protection of selectively islanded microgrids
Hany Fawzy Kamel Habib, Glen Allen, VA (US); Thomas Anthony Kendzia, III, Rockville, VA (US); Veerakumar Bose, Henrico, VA (US); and Christopher Alan Belcastro, Mechanicsville, VA (US)
Assigned to ABB Schweiz AG, Baden (CH)
Filed by ABB Schweiz AG, Baden (CH)
Filed on Aug. 11, 2023, as Appl. No. 18/448,221.
Prior Publication US 2025/0055274 A1, Feb. 13, 2025
Int. Cl. H02H 7/22 (2006.01); H02H 1/00 (2006.01)

CPC H02H 7/22 (2013.01) [H02H 1/0007 (2013.01)]

20 Claims

1. A controller for managing electrical faults in a microgrid, the microgrid including one or more electrical loads, one or more electrical sources, and one or more circuit protection devices that selectively couple the one or more electrical loads and the one or more electrical sources with each other, the controller comprising:

at least one processor configured to:

direct a grid tie switch to open to electrically isolate the microgrid from an electric grid;

determine, in response to directing the grid tie switch to open, that an electrical fault exists in the microgrid;

determine whether a fault current of the electrical fault is less than a threshold value; and

direct the grid tie switch to close to electrically connect the microgrid to the electric grid and increase the fault current above the threshold value in response to determining that the fault current is less than the threshold value.

8. A method of managing electrical faults in a microgrid, the microgrid including one or more electrical loads, one or more electrical sources, and one or more circuit protection devices that selectively couple the one or more electrical loads and the one or more electrical sources with each other, the method comprising:

opening a grid tie switch to open to electrically isolate the microgrid from an electric grid;

determining, in response to opening the grid tie switch, that an electrical fault exists in the microgrid;

determining whether a fault current of the electrical fault is less than a threshold value; and

closing the grid tie switch to open to electrically connect the microgrid to the electric grid and increase the fault current above the threshold value in response to determining that the fault current is less than the threshold value.

15. A microgrid, comprising:

one or more circuit protection devices configured to:

electrically couple one or more electrical loads and one or more electrical sources with each other when subjected to a fault current from an electrical fault that is less than a trip current level; and

electrically decouple the one or more electrical loads and the one or more electrical sources from each other when the fault current is greater than the trip current level;

a grid tie switch configured to selectively couple the microgrid with an electric grid; and

a controller configured to:

direct the grid tie switch to open to electrically isolate the microgrid from the electric grid;

determine, in response to directing the grid tie switch to open, that the fault current exists in the microgrid;

determine whether the fault current is less than the trip current level; and

direct the grid tie switch to close to electrically connect the microgrid to the electric grid and increase the fault current above the trip current level in response to determining that the fault current is less than the trip current level.