ELECTRICAL POWER DISTRIBUTION SYSTEM AND METHOD FOR A GRID-TIED REVERSIBLE SOLID OXIDE FUEL CELL SYSTEM

• US 20170005357A1
• Filed: 07/01/2015
• Published: 01/05/2017
• Est. Priority Date: 07/01/2015
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: MERMELSTEIN, JOSHUA M., ESPINOZA, SERGIO
• Granted Patent: US 9,917,322 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 2250/10 Fuel cells in stationary systems, e.g. emergency power source in plant
• CPC Class Codes: H01M 8/04604 Power, energy, capacity or load
• CPC Class Codes: H01M 8/04671 of the individual fuel cell
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/186 by electrolytic decomposition of the electrolytic solution or the formed water product
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• 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: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A Reversible Solid Oxide Fuel Cell (RSOFC) system includes a Reversible Solid Oxide Fuel Cell (RSOFC) unit, a bi-directional alternating current/direct current (AC/DC) converter, coupled to the RSOFC unit, a common bus, coupled to the bi-directional AC/DC converter and to a power grid, and a plurality of RSOFC subsystems, coupled to receive power only through the common bus. The RSOFC unit has a fuel cell mode, wherein the RSOFC unit produces electrical power from fuel, and an electrolysis mode, wherein the RSOFC unit consumes electrical power to produce the fuel. The bi-directional AC/DC converter is coupled to the RSOFC unit, and is configured to convert direct current (DC) electrical power produced by the RSOFC unit into outgoing alternating current (AC) power, and to convert incoming AC power into DC power for consumption by the RSOFC unit in electrolysis mode.

Claims

1. A Reversible Solid Oxide Fuel Cell (RSOFC) system, comprising:

a Reversible Solid Oxide Fuel Cell (RSOFC) unit, having a fuel cell mode, wherein the RSOFC unit produces electrical power from fuel, and an electrolysis mode, wherein the RSOFC unit consumes electrical power to produce the fuel;

a bi-directional alternating current/direct current (AC/DC) converter, coupled to the RSOFC unit, configured to convert direct current (DC) electrical power produced by the RSOFC unit into outgoing alternating current (AC) power, and to convert incoming AC power into DC power for consumption by the RSOFC unit in electrolysis mode;

a common bus, coupled to the bi-directional AC/DC converter and to a power grid; and

a plurality of RSOFC subsystems, coupled to receive power only through the common bus.

2. A system in accordance with claim 1, wherein the common bus comprises:

a plurality of subsystem circuit breakers, configured to trip on overload condition, coupled only to the RSOFC subsystems; and

a plurality of power circuit breakers, configured to trip on overload condition, coupled only to the bi-directional AC/DC converter and the RSOFC unit.

3. A system in accordance with claim 2, wherein the power circuit breakers are remotely actuable via control wires coupled to a controller, comprising a processor and system memory, and including software for controlling the RSOFC system, the controller being part of the RSOFC subsystems.

4. A system in accordance with claim 3, further comprising:

a power circuit breaker control relay, coupled to the power circuit breakers and to the controller, configured to provide actuation signals to the power circuit breakers in response to control signals from the controller.

5. A system in accordance with claim 2, wherein:

the RSOFC unit comprises a plurality of RSOFC units;

the bi-directional AC/DC converter comprises a plurality of bi-directional AC/DC converters, each RSOFC unit coupled to exactly one bi-directional AC/DC converter; and

the plurality of power circuit breakers comprise one power circuit breaker for each bi-directional AC/DC converter and its corresponding RSOFC unit.

6. A system in accordance with claim 5, wherein actuation of one of the plurality of power circuit breakers stops operation of only the bi-directional AC/DC converter and the corresponding RSOFC unit associated with the one power circuit breaker.

7. A system in accordance with claim 1, wherein the common bus is configured to transmit 480 VAC, 3-phase power between the power grid, the bi-directional AC/DC converter and the RSOFC subsystems.

8. A system in accordance with claim 6, wherein the plurality of RSOFC subsystems include RSOFC system electrical devices, and one or more transformers for transforming the 480 VAC, 3-phase power for use by at least some of the RSOFC system electrical devices.

9. A system in accordance with claim 1, wherein plurality of RSOFC subsystems include a hydrogen compressor, a water supply system, a water deionizer, and a controller, the controller comprising a processor and system memory, and including software for controlling the RSOFC system.

10. A system in accordance with claim 1, wherein the RSOFC unit produces electrical power from gaseous hydrogen fuel in the fuel cell mode, and consumes electrical power to produce hydrogen gas by electrolysis of water in the electrolysis mode.

11. A power distribution system for a Reversible Solid Oxide Fuel Cell (RSOFC) system, comprising:

a common bus, coupled between a power grid and a Reversible Solid Oxide Fuel Cell (RSOFC) system, the common bus including

a plurality of power circuit breakers, configured to trip on overload condition, each power circuit breaker coupled to a bi-directional AC/DC converter that is coupled to a Reversible Solid Oxide Fuel Cell (RSOFC) unit having a power generation mode and a power-consuming electrolysis mode; and

a plurality of subsystem circuit breakers, configured to trip on overload condition, each subsystem circuit breaker coupled to at least one of a plurality of RSOFC subsystems, whereby the plurality of RSOFC subsystems receive power only through the common bus, whether the RSOFC units are operating in power generation mode or electrolysis mode.

12. A system in accordance with claim 11, wherein the plurality of power circuit breakers are remotely actuable.

13. A system in accordance with claim 12, wherein the RSOFC subsystems include a controller, comprising a processor and system memory and including software for controlling the RSOFC system, the controller being coupled to control the remotely actuable power circuit breakers.

14. A system in accordance with claim 11, wherein the RSOFC units are configured to produce electrical power from hydrogen gas when in the power generation mode, and are configured to consume electrical power to produce hydrogen gas when in the electrolysis mode.

15. A system in accordance with claim 11, wherein the common bus is configured to transmit 480V AC, 3-phase power between the power grid, the bi-directional AC/DC converters and the RSOFC subsystems.

16. A method for controlling a Reversible Solid Oxide Fuel Cell (RSOFC) system, comprising:

selectively operating a fuel cell unit of a Reversible Solid Oxide Fuel Cell (RSOFC) system in either electrolysis mode or in fuel cell mode;

providing power to the fuel cell unit from a power grid coupled to the RSOFC system via a common bus using a bi-directional alternating current/direct current (AC/DC) converter, when operating in electrolysis mode;

distributing power from the fuel cell unit to the power grid via the common bus using the bi-directional AC/DC converter, when operating in fuel cell mode; and

powering electrical subsystems of the RSOFC system via the common bus when the fuel cell unit operates in either electrolysis mode or fuel cell mode.

17. A method in accordance with claim 16, further comprising:

providing power to the fuel cell unit using a bi-directional AC/DC converter coupled between the fuel cell unit and the common bus, when operating in electrolysis mode; and

distributing power from the fuel cell unit using the bi-directional AC/DC converter when operating in fuel cell mode;

18. A method in accordance with claim 16, further comprising:

selectively operating a plurality of fuel cell units of the RSOFC system in either electrolysis mode or in fuel cell mode;

providing power to the plurality of fuel cell units from the power grid via the common bus using the bi-directional AC/DC converter, when operating in electrolysis mode;

distributing power from the plurality of fuel cell units to the power grid via the common bus using the bi-directional AC/DC converter, when operating in fuel cell mode;

powering electrical subsystems of the RSOFC system via the common bus when the plurality of fuel cell units operate in either electrolysis mode or fuel cell mode; and

isolating a selected one of the plurality of fuel cell units through actuation of a power circuit breaker when a fault is detected in operation of the one of the plurality of fuel cell units, while allowing a reminder of the RSOFC system to operate.

19. A method in accordance with claim 18, further comprising coupling each fuel cell unit with a unique bi-directional AC/DC converter and with a unique power circuit breaker, whereby actuation of one power circuit breaker stops operation of only the bi-directional AC/DC converter associated with the one power circuit breaker.

20. A method in accordance with claim 16, further comprising selectively operating the fuel cell unit in either electrolysis mode or in fuel cell mode in response to signals from the power grid to a controller of the RSOFC system, indicating a power demand or power surplus condition of the power grid.