Methods of fuel cell operation with bi-directional inverters

Patent metadata

Field	Value
Publication number	US-11637507-B2
Application number	US-202117317759-A
Country	US
Kind code	B2
Filing date	May 11, 2021
Priority date	May 18, 2020
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

A microgrid system includes first and second DC power sources electrically connected to respective first and second DC electrical power busses, a first uninterruptable power module electrically connected to the first DC electrical power bus and configured to be connected to an alternating current (AC) load, a second uninterruptable power module electrically connected to the second DC electrical power bus and configured to be connected to the AC load, a first bi-directional AC/DC inverter having a DC end and an AC end, where the first DC electrical power bus is connected to the DC end of the first bi-directional AC/DC inverter, a second bi-directional AC/DC inverter having DC and AC ends, where the second DC electrical power bus is connected to the DC end of the second bi-directional AC/DC inverter, and an AC electrical power bus electrically connected to the first and second bi-directional AC/DC inverters at their AC ends.

First claim

What is claimed is:

1. A microgrid system, comprising:
a first direct current (DC) power source electrically connected to a first DC electrical power bus;
a second DC power source electrically connected to a second DC electrical power bus;
a first uninterruptable power module electrically connected to the first DC electrical power bus and configured to be connected to an alternating current (AC) load;
a second uninterruptable power module electrically connected to the second DC electrical power bus and configured to be connected to the AC load;
a first bi-directional AC/DC inverter having a DC end and an AC end, wherein the first DC electrical power bus is connected to the DC end of the first bi-directional AC/DC inverter;
a second bi-directional AC/DC inverter having a DC end and an AC end, wherein the second DC electrical power bus is connected to the DC end of the second bi-directional AC/DC inverter;
an AC electrical power bus electrically connected to the first and the second bi-directional AC/DC inverters at their AC ends; and
a control device communicatively connected to the first bi-directional AC/DC inverter and the second bi-directional AC/DC inverter and configured with control device executable code configured to cause the control device to execute operations comprising:
configuring the second bi-directional AC/DC inverter to provide supplemental AC power to the AC electrical power bus; and
configuring the first bi-directional AC/DC inverter to import at least part of the supplemental AC electrical power from the AC electrical power bus.

2. The microgrid system of claim 1 , wherein the control device configured with control device executable code configured to cause the control device to execute operations further comprising:
determining if first DC electrical power output by the first DC power source to the first DC electrical power bus is less than, equal to or greater than a DC electrical power threshold to be provided to the first uninterruptable power module; and
in response to determining that the first DC electrical power is less than the DC electrical power threshold, importing the supplemental AC electrical power from the AC electrical power bus by the first bi-directional AC/DC inverter, and providing a second DC electrical power from the first bi-directional AC/DC inverter to the first DC electrical power bus, such that the first DC electrical power and the second DC electrical power are not less than the DC electrical power threshold.

3. The microgrid system of claim 2 , wherein the control device is configured with control device executable code configured to cause the control device to execute operations such that:
in response to determining that the first DC electrical power is less than the DC electrical power threshold, providing a portion of a DC electrical power output by the second DC power source to the second bi-directional inverter though the second DC electrical power bus; and
providing the supplemental AC power from the second bi-directional AC/DC inverter to the AC electrical power bus.

4. The microgrid system of claim 3 , wherein the control device is configured with control device executable code configured to cause the control device to execute operations such that:
in response to determining that the first DC electrical power is greater than the DC electrical power threshold, providing excess DC electrical power which exceeds DC electrical power threshold to the first bi-directional AC/DC inverter;
converting the excess DC electrical power to additional AC electrical power in the first bi-directional AC/DC inverter; and
exporting the additional AC electrical power to the AC power bus.

5. The microgrid system of claim 3 , further comprising a selective electrical connector electrically connected to the AC electrical power bus and electrically connectable to an electrical power utility grid,
wherein the control device is configured with control device executable code configured to cause the control device to execute operations further comprising:
determining whether AC electrical power is available from the electrical power utility grid; and
selectively electrically disconnecting the AC electrical power bus from the electrical power utility grid by opening the selective electrical connector in response to determining that AC electrical power is not available from the electrical power utility grid.

6. The microgrid system of claim 5 , further comprising an auxiliary electrical power storage unit,
wherein the control device is configured with control device executable code configured to cause the control device to execute operations further comprising:
in response to determining that the first DC electrical power is less than the DC electrical power threshold:
determining whether the supplemental AC electrical power on the AC electrical power bus is sufficient to meet the DC electrical power threshold; and
drawing additional AC electrical power from at least one of the electrical power utility grid or the auxiliary electrical power storage unit by the first bi-directional AC/DC inverter in response to determining that the supplemental AC electrical power on the AC electrical power bus is not sufficient to meet the DC electrical power threshold.

7. The microgrid system of claim 6 , wherein the control device is configured with control device executable code configured to cause the control device to execute operations further comprising:
determining whether excess AC electrical power is provided on the AC electrical power bus;
determining whether a charge of the auxiliary electrical power storage unit exceeds a charge threshold; and
charging the auxiliary electrical power storage unit using the excess AC electrical power from the AC electrical power bus in response to determining that there is excess AC electrical power on the AC electrical power bus and that the charge of the auxiliary electrical power storage unit does not exceed the charge threshold.

8. The microgrid system of claim 7 , further comprising an electrical power dissipation unit electrically connected to the AC electrical power bus,
wherein the control device is configured with control device executable code configured to cause the control device to execute operations further comprising:
determining whether there is excess AC electrical power on the AC electrical power bus after charging the auxiliary electrical power storage unit and whether the electrical power utility grid is electrically connected to the AC electrical power bus; and
dissipating the excess AC electrical power from the AC electrical power bus by the electrical power dissipation unit in response to determining that there is excess AC electrical power on the AC electrical power bus and that the electrical power utility grid is not electrically connected to the AC electrical power bus.

9. The microgrid system of claim 2 , wherein:
the first DC power source comprises a first fuel cell power module cluster comprising a plurality of first fuel cell power modules;
the second DC power source comprises a second fuel cell power module cluster comprising a plurality of second fuel cell power modules; and
the first DC electrical power is less than the DC electrical power threshold when at least one first fuel cell power module fails or degrades.

10. The microgrid system of claim 2 , wherein:
the first and the second uninterruptable power modules comprise unidirectional DC/AC inverters; and
the control device is configured with control device executable code configured to cause the control device to execute operations such that the first and the second uninterruptable power modules provide a same amount of AC e

Assignees

• Bloom Energy Corp

Inventors

• Pmsvvsv Prasad
• Baker Beau
• METCHO Craig

Classifications

• H02J2105/10

  Local stationary networks having a local or delimited stationary reach · CPC title

• H02J2101/30

  Fuel cells · CPC title

• H01M2008/1293

  Fuel cells with solid oxide electrolytes · CPC title

• H01M8/249

  comprising two or more groupings of fuel cells, e.g. modular assemblies · CPC title

• H02J9/062

  for AC powered loads · CPC title