Methods and apparatus for controlled solid oxide fuel cell (SOFC)/turbine hybrid power generation

1. A method for operating a pressurized solid oxide fuel cell/turbine (SOFC/turbine) hybrid power generation system comprising a solid oxide fuel cell (SOFC) generator and a turbine generator, said method comprising:

controlling airflow to the SOFC/turbine hybrid power generation system in accordance with power demand; and

utilizing electrical current drawn from the SOFC generator to regulate SOFC generator temperature.

2. A method in accordance with claim 1 wherein said controlling airflow to the SOFC/turbine hybrid generation power system further comprises controlling an airflow setpoint as a function of power demand.

3. A method in accordance with claim 2 wherein said controlling airflow to the SOFC/turbine hybrid power generation system further comprises controlling a turbine rotational speed dependent upon the airflow setpoint.

4. A method in accordance with claim 1 wherein the SOFC/turbine hybrid power generation system further comprises using electrical current drawn from the SOFC generator to control cooling of the SOFC generator to thereby maintain a predetermined SOFC temperature setpoint.

5. A method in accordance with claim 1 further comprising controlling the airflow in accordance with the power demand.

6. A method in accordance with claim 1 further comprising controlling a fuel flow, dependent upon a current demand, to meet a desired SOFC power.

7. A method in accordance with claim 1 further comprising varying SOFC fuel flow to trim output voltage so that a total plant power output matches a demanded power output.

8. A method in accordance with claim 1 wherein said controlling airflow to the SOFC/turbine hybrid power generation system in accordance with power demand further comprises controlling an airflow setpoint as a function of power demand and controlling a turbine rotational speed dependent upon the airflow setpoint and said method further comprises cooling the SOFC generator to maintain a predetermined SOFC temperature setpoint.

9. A power generation system comprising:

a solid oxide fuel cell (SOFC) hybrid plant comprising a pressurized solid oxide fuel cell (SOFC) generator, an unreacted fuel combustor, and a turbine generator, said SOFC generator and turbine generator, wherein said SOFC generator and said turbine generator are configured to provide a summed power output of said SOFC hybrid plant; and

a system controller configured to meet load requirements of said SOFC hybrid plant while maintaining temperature constraints on said SOFC generator and said unreacted fuel combustor.

10. A power generation system in accordance with claim 9 wherein said system controller further comprises an airflow controller configured to limit response time of said power generation system to thereby maintain a surge margin during airflow changes of said turbine generator.

11. A power generation system in accordance with claim 10 wherein said controller further comprises an airflow setpoint controller configured to control an airflow setpoint as a function of power demand.

12. A power generation system in accordance with claim 11 wherein said system controller further comprises a turbine speed controller configured to control said turbine generator to satisfy a rotational speed requirement.

13. A power generation system in accordance with claim 9 wherein said system controller further comprises an SOFC current controller configured to control cooling of said SOFC generator to maintain a predetermined SOFC temperature setpoint.

14. A power generation system in accordance with claim 13 wherein said system controller further comprises a fuel utilization controller configured to control a fuel flow, dependent upon current demand, to meet a desired SOFC generator power.

15. A power generation system in accordance with claim 9 wherein said system controller comprises:

an airflow controller configured to limit response time of said power generation system to thereby maintain a surge margin during airflow changes of said turbine generator;

an airflow setpoint controller configured to control an airflow setpoint as a function of power demand;

a turbine speed controller configured to control said turbine generator to satisfy a rotational speed requirement;

an SOFC current controller configured to cool said SOFC generator to maintain a predetermined SOFC temperature setpoint; and

a fuel utilization controller configured to control a fuel flow, dependent upon current demand, to meet a desired SOFC generator power.

16. A system controller for a hybrid power generation plant having a solid oxide fuel cell (SOFC) generator, a turbine generator, and an unreacted fuel combustor, said system controller configured to cool the SOFC generator to maintain a predetermined SOFC temperature setpoint and to maintain a surge margin during airflow changes of the turbine generator.

17. A system controller in accordance with claim 16 wherein said system controller comprises an airflow controller configured to limit a response time of the hybrid power generation plant.

18. A system controller in accordance with claim 17 wherein said system controller further comprises an airflow setpoint controller configured to control an airflow setpoint as a function of power demand.

19. A system controller in accordance with claim 18 wherein said system controller further comprises a turbine speed controller configured to control the turbine generator to satisfy a rotational speed requirement.

20. A system controller in accordance with claim 19 wherein said system controller further comprises a fuel utilization controller configured to control a fuel flow, dependent upon current demand, to meet a desired fuel cell power.