Fuel cell power plant control to prevent reactant starvation during islanded mode of operation

Patent metadata

Field	Value
Publication number	US-12368174-B2
Application number	US-201916595783-A
Country	US
Kind code	B2
Filing date	Oct 8, 2019
Priority date	Oct 8, 2019
Publication date	Jul 22, 2025
Grant date	Jul 22, 2025

Abstract

An illustrative example controller for a fuel cell power plant includes at least one processor and memory associated with the processor. The processor is configured to control operation of the fuel cell power plant during an islanded mode of operation wherein the fuel cell power plant provides output power to a load. The processor is configured to control the operation of the fuel cell power plant in the islanded mode by adjusting a droop gain of the controller to change the output power of the fuel cell power plant in response to a change in demand from the load. While adjusting the droop gain, the processor is configured to maintain a portion of the demand from the load met by the output power of the fuel cell power plant within a predetermined allocation of islanded mode load sharing assigned to the fuel cell power plant, maintain a ramp up rate of the output power of the fuel cell power plant within a predetermined maximum ramp up capability of the fuel cell power plant, and maintain a frequency of the output power of the fuel cell power plant within a predetermined range.

First claim

I claim:

1. A controller for a fuel cell power plant, the controller comprising:
at least one processor and memory associated with the processor, the processor being configured to control operation of the fuel cell power plant during an islanded mode of operation wherein the fuel cell power plant provides output power to a load, the processor being configured to control the operation of the fuel cell power plant in the islanded mode by
adjusting a droop gain of the controller to change the output power of the fuel cell power plant in response to a change in demand from the load while:
maintaining a portion of the demand from the load met by the output power of the fuel cell power plant within a predetermined allocation of islanded mode load sharing assigned to the fuel cell power plant,
maintaining a ramp up rate of the output power of the fuel cell power plant within a predetermined maximum ramp up capability of the fuel cell power plant, and
maintaining a frequency of the output power of the fuel cell power plant within a predetermined range.

2. The controller of claim 1 , wherein the processor is configured to control a rate at which the droop gain changes to maintain stability of the fuel cell power plant.

3. The controller of claim 2 , wherein the processor includes a filter that controls the rate at which the droop gain changes.

4. The controller of claim 3 , wherein the filter prevents a change in the droop gain during a predetermined time lag in response to the change in the load demand.

5. The controller of claim 1 , wherein
the processor is configured to determine a droop gain adjustment factor for adjusting the droop gain to maintain the portion of the demand from the load met by the output power of the fuel cell power plant within the predetermined allocation; and
the processor is configured to determine the droop gain adjustment factor by
determining an instantaneous ramp up rate of the output power of the fuel cell power plant, and
setting the droop gain adjustment factor equal to: (the instantaneous ramp up rate)×(a predetermined frequency droop gain)/(a predetermined maximum ramp up rate of the output power of the fuel cell power plant).

6. The controller of claim 5 , wherein the processor is configured to determine the instantaneous ramp up rate by determining a derivative of the current output power.

7. The controller of claim 6 , wherein
the determined derivative is zero during a steady state condition of the demand of the load; and
the processor applies the predetermined fixed frequency droop gain during the steady state condition of the demand of the load.

8. The controller of claim 1 , wherein the processor is configured to maintain the ramp up rate of the output power of the fuel cell power plant within the predetermined maximum ramp up capability of the fuel cell power plant by
determining an instantaneous ramp up rate of the output power of the fuel cell power plant; and
adjusting the droop gain by a droop gain adjustment factor when the instantaneous ramp up rate is greater than the maximum ramp up capability,
or
setting the droop gain adjustment factor to zero when the instantaneous ramp up rate is below the maximum ramp up capability.

9. The controller of claim 1 , wherein the processor is configured to maintain the frequency of the output power of the fuel cell power plant within the predetermined range by
setting a maximum droop gain adjustment factor to be equal to: (a predetermined maximum frequency droop)/(a current output power of the fuel cell power plant)−(a predetermined fixed frequency droop gain); and
adjusting the droop gain using a droop gain adjustment factor that is less than or equal to the maximum droop gain adjustment factor.

10. A fuel cell power plant comprising at least one cell stack assembly including a plurality of fuel cells and the controller of claim 1 .

11. A method of controlling a fuel cell power plant, the method comprising:
determining that the fuel cell power plant is operating in an islanded mode wherein the fuel cell power plant provides output power to a load; and
adjusting a droop gain to change an output power of the fuel cell power plant in response to a change in demand from the load while:
maintaining a portion of the demand from the load met by the output power of the fuel cell power plant within a predetermined allocation of islanded mode load sharing assigned to the fuel cell power plant,
maintaining a ramp up rate of the output power of the fuel cell power plant within a predetermined maximum ramp up capability of the fuel cell power plant, and
maintaining a frequency of the output power of the fuel cell power plant within a predetermined range.

12. The method of claim 11 , comprising controlling a rate at which the droop gain changes to maintain stability of the fuel cell power plant.

13. The method of claim 12 , comprising using a filter that controls the rate at which the droop gain changes.

14. The method of claim 13 , wherein the filter prevents a change in the droop gain during a predetermined time lag in response to the change in the load demand.

15. The method of claim 11 , comprising
determining a droop gain adjustment factor for adjusting the droop gain for maintaining the portion of the demand from the load met by the output power of the fuel cell power plant within the predetermined allocation; and
determining the droop gain adjustment factor by
determining an instantaneous ramp up rate of the output power of the fuel cell power plant, and
setting the droop gain adjustment factor equal to: (the instantaneous ramp up rate)×(a predetermined frequency droop gain)/(a predetermined maximum ramp up rate of the output power of the fuel cell power plant).

16. The method of claim 15 , comprising determining the instantaneous ramp up rate by determining a derivative of the current output power.

17. The method of claim 16 , wherein
the determined derivative is zero during a steady state condition of the demand of the load; and
the method comprises applying the predetermined fixed frequency droop gain during the steady state condition of the demand of the load.

18. The method of claim 11 , wherein maintaining the ramp up rate of the output power of the fuel cell power plant within the predetermined maximum ramp up capability of the fuel cell power plant comprises
determining an instantaneous ramp up rate of the output power of the fuel cell power plant; and
adjusting the droop gain by a droop gain adjustment factor when the instantaneous ramp up rate is less than the maximum ramp up capability
or
setting the droop gain adjustment factor to zero when the instantaneous ramp up rate exceeds the maximum ramp up capability.

19. The method of claim 11 , wherein maintaining the frequency of the output power of the fuel cell power plant within the predetermined range comprises
setting a maximum droop gain adjustment factor to be equal to: (a predetermined maximum frequency droop)/(a current output power of the fuel cell power plant)−(a predetermined fixed frequency droop gain); and
adjusting the droop gain using a droop gain adjustment factor that is less than or equal to the maximum droop gain adjustment factor.

Assignees

• Doosan Fuel Cell America Inc

Inventors

• Cingoz Fatih

Classifications

• H01M8/04932

  of the individual fuel cell · CPC title

• Y02B90/10

  Applications of fuel cells in buildings · CPC title

• Y02E60/50

  Fuel cells · CPC title

• H01M2250/10

  Fuel cells in stationary systems, e.g. emergency power source in plant · CPC title

• H01M8/0494

  of fuel cell stacks · CPC title