System for providing assured power to a critical load

• US 6,465,910 B2
• Filed: 02/13/2001
• Issued: 10/15/2002
• Est. Priority Date: 02/13/2001
• Status: Expired

• Current Assignee: UTC Fuel Cells, LLC
• Original Assignee: UTC Fuel Cells, LLC
• Inventors: Young, Douglas Gibbons, Ross, Ricky M., Healy, Herbert C., Fragola, Francis A. Jr.
• Primary Examiner(s): Jackson, Stephen W.
• Assistant Examiner(s): DeBeradinis, Robert L
• Application Number:
  US09/782,402
• Publication Number:
  US 20020109410A1
• Time in Patent Office: 609 Days
• Field of Search: 307/64, 307/70, 307/43, 307/44, 307/45, 307/80
• US Class Current: 307/64
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings

Abstract

A power system (8) is provided for economically supplying uninterrupted electrical power to one or more critical loads (14). One or more fuel cell power plants (18) provide one substantially continuous source of power, and a utility grid (10) provides another source of power. The fuel cell power plants (18) are adapted to be, and are, normally substantially continuously connected and providing power to, the critical load(s) (14). A rapidly-acting static switch (19) selectively connects and disconnects the grid power supply (10) to the critical load(s) (14) and with the fuel cell power plant(s) (18). A switch controller (49, 45) controls the state of the static switch (19) to connect the grid power source (10) with the critical load(s) (14) and the fuel cell power plant(s) (18) during normal operation of the grid (10), and to rapidly (less than 4 ms) disconnect the grid power source (10) from the load(s) (14) and fuel cell power plant(s) (18) when operation of the grid (10) deviates from normal beyond a limit.

Claims

1. A power system (8) for providing uninterrupted electric power to a critical load (14), comprising:

a. a first power source (10) providing sufficient power to supply the critical load (14);

b. a second power source (18) comprising at least one fuel cell power plant (18), the second power source providing sufficient power to supply the critical load (14) and adapted to be normally substantially continuously connected and providing power to, the critical load (14);

c. a static switch (19) for selectively connecting and disconnecting the first power source (10) to the second power source (18) and (to) the critical load (14); and

d. a switch controller (49, 45 )for controlling the state of the static switch (19) to connect the first power source (10) with the critical load (14) and the second power source (18) during normal operation of the first power source (10) and to rapidly disconnect the first power source (10) from the critical load (14) and the second power source (18)if and when operation of the first power source (10) deviates beyond a limit from normal.

2. The power system (8) of claim 1 wherein the switch controller (49, 45) additionally controls the state of the static switch (19) to rapidly reconnect the first power source (10) with the critical load (14) and the second power source (18) when the first power source (10) returns to normal operation.

3. The power system (8) of claim 1 wherein the second power source (18) comprises only one or more fuel cell power plants (18).

4. The power system (8) of claim 1 wherein the static switch (19) is a solid-state device.

5. The power system (8) of claim 4 wherein the solid-state device is a thyristor (19).

6. The power system (8) of claim 1 wherein the first power source (10) is a utility power grid and wherein each fuel cell power plant (18) includes a power conditioning system (PCS) for configuring operation of the respective fuel cell (18) in a grid connected mode or in a grid independent mode in response to mode control signals (D1/401′

, D2/402′

), and including a site management controller (31) connected intermediate the switch controller (49, 45) and the power conditioning system (PCS) and responsive to preliminary mode signals (M1/401, M2/402) from the switch controller (49, 45) for providing the mode control signals (D1/401′

, D2/402′

) to the fuel cell power conditioning system (PCS), whereby the fuel cell power plants (18) rapidly transition operation between the grid connected and the grid independent modes.

7. The power system of claim 6 wherein the rapid disconnection of the first power source (10) from the critical load (14) and the second power source (18), and the rapid transitioning of operation of the at least one fuel cell (18) between the grid connected mode and the grid independent mode occurs within an interval of about 4 milliseconds.

8. The power system of claim 1 wherein the rapid disconnection of the first power source (10) from the critical load (14) and the second power source (18) occurs within an interval of about 4 milliseconds.

9. A power system (8) for providing substantially continuous electric power to at least a critical load (14), comprising:

a. a utility grid power source (10) providing sufficient power to supply the critical load (14);

b. at least one fuel cell power plant (18) operating substantially continuously for providing at least sufficient power to supply the critical load (14), the at least one fuel cell power plant (18) including a power conditioning system (PCS) for configuring operation of the respective fuel cell (18) in a grid connected mode or in a grid independent mode in response to mode control signals (D1/401′

, D2/402′

), the at least one fuel cell power plant (18) being normally substantially continuously connected and providing power to, the critical load (14);

c. a static switch (19) for selectively connecting and disconnecting the grid power source (10) to the at least one fuel cell power plant (18) and to the critical load (14);

d. a switch controller (49, 45) for controlling the state of the static switch (19) to connect the grid power source (10) with the critical load (14) and the at least one fuel cell power plant (18) during normal operation of the grid power source (10) and to disconnect, within a 4 millisecond interval, the grid power source (10) from the critical load (14) and the at least one fuel cell power plant (18) when the grid power source deviates beyond a limit from normal; and

e. a site management controller (31) connected between the switch controller (49, 45) and the power conditioning system (PCS) and responsive to preliminary mode signals (M1/401, M2/402) from the switch controller (49, 45) for providing the mode control signals (D1/401′

, D2/402′

) to the fuel cell power conditioning system (PCS) to cause the at least one fuel cell power plant (18) to rapidly transition operation, within a 4 millisecond interval, between the grid connected mode and the grid independent mode.

10. A power system (8) for providing substantially continuous electric power to at least a critical load (14), comprising:

a. a utility grid power source (10) providing sufficient power to supply the critical load (14);

b. at least one fuel cell power plant (18) operating substantially continuously for providing at least sufficient power to supply the critical load (14), the at least one fuel cell power plant (18) including a power conditioning system (PCS) for configuring operation of the respective fuel cell (18) in a grid connected mode or in a grid independent mode in response to mode control signals (D1/401′

, D2/402′

), the at least one fuel cell power plant (18) being normally substantially continuously connected and providing power to, the critical load (14);

c. a static switch (19) for selectively connecting and disconnecting the grid power source (10) to the at least one fuel cell power plant (18) and to the critical load (14);

d. a switch controller (49, 45) for controlling the state of the static switch (19) to connect the grid power source (10) with the critical load (14) and the at least one fuel cell power plant (18) during normal operation of the grid power source (10) and to disconnect, within less than an 8.3 millisecond interval, the grid power source (10) from the critical load (14) and the at least one fuel cell power plant (18) when the grid power source deviates beyond a limit from normal; and

e. a site management controller (31) connected with the switch controller (49, 45) and the power conditioning system (PCS) and responsive to the switch controller (49, 45) for providing mode control signals (D1/401′

, D2/402′

) to the fuel cell power conditioning system (PCS) to cause the at least one fuel cell power plant (18) to rapidly transition operation, within less than an 8.3 millisecond interval, between the grid connected mode and the grid independent mode.

11. The power system (8) of claim 10 wherein the at least one fuel cell power plant (18) is caused to rapidly transition operation between the grid connected mode and the grid independent mode in an interval of less than about 4 milliseconds.