REDUNDANT POINT OF COMMON COUPLING (PCC) TO REDUCE RISK OF MICROGRID'S ISLANDING

• US 20160285268A1
• Filed: 09/03/2013
• Published: 09/29/2016
• Est. Priority Date: 09/03/2013
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited
• Original Assignee: ABB Technology Limited (ABB Ltd.)
• Inventors: MAJUMDER, Ritwik
• Granted Patent: US 9,935,463 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02J 3/472 For selectively connecting the AC sources in a particular order, e.g. sequential, alternating or subsets of sources
• CPC Class Codes: H02J 3/48 Controlling the sharing of the in-phase component
• CPC Class Codes: Y02P 80/14 District level solutions, i.e. local energy networks

Abstract

A microgrid connecting at least one distributed electricity generator includes a first switch configured for, in a closed position, connecting the microgrid to a first network line at a first point of common coupling (PCC) and for, in an open position, disconnecting the microgrid from the first network line at the first PCC; a second switch configured for, in a closed position, connecting the microgrid to a second network line at a second PCC, and for, in an open position, disconnecting the microgrid from the second network line at the second PCC; and a control unit configured for, when an islanding event has been detected when the second switch is in its closed position and the first switch is in its open position, acting to close the first switch, bringing it to its closed position.

Claims

1-10. -10. (canceled)

11. A microgrid connecting at least one distributed electricity generator, the microgrid comprising:

a first switch configured for, in a closed position, connecting the microgrid to a first network line at a first point of common coupling, PCC, and for, in an open position, disconnecting the microgrid from the first network line at the first PCC;

a second switch configured for, in a closed position, connecting the microgrid to a second network line at a second PCC, and for, in an open position, disconnecting the microgrid from the second network line at the second FCC; and

a control unit configured for, when the second switch is in the closed position and the first switch is in the open position;

periodically receiving information about a grid voltage at the first PCC;

detecting an islanding event at the second PCC; and

in response to the detected islanding event, acting to close the first switch for bringing the first switch to the closed position.

12. The microgrid of claim 11, wherein the control unit is also configured for acting to open the second switch, bringing the second switch to the open position, in response to the detected islanding event.

13. The microgrid of claim 11, wherein the first network line is comprised in the same network grid as the second network line.

14. The microgrid of claim 11, wherein the first network line is comprised in a first network grid and the second network line is comprised in a second network grid, different than the first network grid.

15. The microgrid of claim 11, wherein the control unit is also configured for receiving information about a voltage of at least one bus in the microgrid and a power of the distributed electricity generator.

16. The microgrid of claim 11, wherein the control unit is also configured for periodically receiving information about a power flow in the microgrid.

17. The microgrid of claim 11, wherein the control unit is also configured for calculating a flow reference for the first PCC when the first switch is in the open position, and for using said power reference for controlling power flow over the first PCC when the first switch is in the closed position.

18. The microgrid of claim 11, wherein the control unit comprises a central controller, a first interface controller for controlling power flow over the first PCC and a second interface controller for controlling power flow over the second PCC.

19. The microgrid of claim 11, further comprising:

a third switch configured for, in a closed position, connecting the microgrid to a third network line at a third PCC, and for, in an open position, disconnecting the microgrid from the third network line at the third PCC,

wherein the control unit is also configured for acting to close the third switch, bringing the third switch from the open position to the closed position, in response to the detected islanding event.

21. The microgrid of claim 12, wherein the first network line is comprised in the same network grid as the second network line.

22. The microgrid of claim 12, wherein the first network line is comprised in a first network grid and the second network line is comprised in a second network grid, different than the first network grid.

23. The microgrid of claim 12, wherein the control unit is also configured for receiving information about a voltage of at least one bus in the microgrid and a power of the distributed electricity generator.

24. The microgrid of claim 13, wherein the control unit is also configured for receiving information about a voltage of at least one bus in the microgrid and a power of the distributed electricity generator.

25. The microgrid of claim 14, wherein the control unit is also configured for receiving information about a voltage of at least one bus in the microgrid and a power of the distributed electricity generator.

26. The microgrid of claim 12, wherein the control unit is also configured for periodically receiving information about a power flow in the microgrid.

27. The microgrid of claim 13, wherein the control unit is also configured for periodically receiving information about a power flow in the microgrid.

28. The microgrid of claim 14, wherein the control unit is also configured for periodically receiving information about a power flow in the microgrid.

29. The microgrid of claim 15, wherein the control unit is also configured for periodically receiving information about a power flow in the microgrid.

30. The microgrid of claim 12, wherein the control unit is also configured for calculating a flow reference for the first PCC when the first switch is in the open position, and for using said power reference for controlling power flow over the first PCC when the first switch is in the closed position.

20. A method performed by a control unit for a microgrid connecting at least one distributed electricity generator and comprising a second switch in a closed position, connecting the microgrid to a second network line at a second point of common coupling, PCC, and a first switch in an open position, disconnecting the microgrid from a first network line at a first PCC, the method comprising the steps of:

periodically receiving information about a grid voltage at the first PCC;

detecting an islanding event at the second PCC; and

acting to close the first switch, for bringing the first switch to the closed position, in response to the detected islanding event.