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An electric power plant includes an array of fuel cell systems. The fuel cell systems are electrically couplable in series and/or parallel combinations to provide a variety of output powers, output current and/or output voltages. The fuel cell systems are "hot swappable" and redundant fuel cell sys

An electric power plant includes an array of fuel cell systems. The fuel cell systems are electrically couplable in series and/or parallel combinations to provide a variety of output powers, output current and/or output voltages. The fuel cell systems are "hot swappable" and redundant fuel cell systems may automatically replace faulty fuel cell systems to maintain output power, current and/or voltage.

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I claim: 1. An electric power plant comprising: a power supply system, the power supply system comprising: a power bus, a first and second fuel cell system, each fuel cell system comprising a fuel cell stack, an electrical power storage device electrically coupled in parallel with the fuel cell sta

I claim: 1. An electric power plant comprising: a power supply system, the power supply system comprising: a power bus, a first and second fuel cell system, each fuel cell system comprising a fuel cell stack, an electrical power storage device electrically coupled in parallel with the fuel cell stack, and means for controlling a flow of current from the fuel cell stack to the electrical power storage device and the power bus, a first switch selectively operable to electrically couple the first fuel cell system in series in the power bus, and a second switch selectively operable to electrically couple the second fuel cell system in series in the power bus; an oxidant supply system for supplying an oxidant gas to at least one of the fuel cell stacks; and a fuel supply system for supplying a fuel gas to at least one of the fuel cell stacks, wherein the first switch is selectively operable according to an operating condition of the first fuel cell system, and wherein the power supply system further comprises a first redundancy switch electrically coupled in series with the first switch and selectively operable therewith to electrically couple the first fuel cell system in series to the power bus, the first redundancy switch being selectively operable according to at least one of the operating condition of at least the second fuel cell system, a voltage across the power bus, a desired output of the power supply system and a desired nominal current output of the power supply system. 2. The power plant of claim 1 wherein the first fuel cell system comprises a first fuel cell stack, a first electrical storage device electrically coupled in parallel with the first fuel cell stack, a first series pass element electrically coupled in between the first fuel cell stack and the first electrical storage device, and a first regulating circuit controllingly coupled to the first series pass element, and wherein the second fuel cell system comprises a second fuel cell stack, a second electrical storage device electrically coupled in parallel with the second fuel cell stack, a second series pass element electrically coupled between the second fuel cell stack and the second electrical storage device, and a second regulating circuit controlling coupled to the second series pass element. 3. The power plant of claim 1 wherein the first fuel cell system comprises a first fuel cell stack, and a first reactant supply system having a first control element operable to control a partial pressure of at least a first reactant to the first fuel cell stack, and wherein the second fuel cell system comprises a second fuel cell stack, and a second reactant supply system having a second control element operable to control a partial pressure of at least a first reactant to the second fuel cell stack. 4. The power plant of claim 1 wherein the first switch is one of a contactor and a transistor. 5. The power plant of claim 1 wherein the power supply further comprises a third fuel cell system, and a third switch selectively operable to electrically couple the third fuel cell system in series in the power bus. 6. The power plant of claim 1 wherein the power supply system further comprises a third fuel cell system, and a third switch selectively operable to electrically couple the third fuel cell system in the power bus in parallel with at least one of the first and the second fuel cell systems. 7. The power plant of claim 1 wherein the power supply system further comprises a first diode electrically coupled in series in the power bus between the first and the second fuel cell systems. 8. The electric power plant of claim 1 wherein the first switch is closed to electrically couple the first fuel cell system in series with the power bus, and wherein the first switch is opened upon the operating condition corresponding to a fault or a failure in its respective fuel cell stack. 9. The electric power plant of claim 8 wherein the first switch is a fault switch. 10. The electric power plant of claim 8, further comprising: a controller operable to close and open its respective fuel cell stack based upon the operating condition corresponding to the fault or the failure. 11. A method for operating an electric power plant having at least a first fuel cell system comprising a first fuel cell stack, an electrical power storage device electrically coupled in parallel with the first fuel cell stack, and a first switch to couple the first fuel cell system to a power bus; a second fuel cell system comprising a second fuel cell stack, another electrical power storage device electrically coupled in parallel with the second fuel cell stack, and a second switch to couple the second fuel cell system to the power bus; wherein the first fuel cell system further comprises a redundancy switch in series with the first switch and the power bus, the method comprising: closing the first switch and the redundancy switch of the first fuel cell system to electrically couple the first fuel cell system to the power bus, wherein the redundancy switch is selectively operable according to at least one of an operating condition of at least the second fuel cell system, a voltage across the power bus, a desired output of a power supply system and a desired nominal current output of the power supply system. 12. The method of claim 11, further comprising: opening the redundancy switch upon detection of the operating condition. 13. The method of claim 11, further comprising: opening the first switch to disconnect the first fuel cell system from the power bus upon occurrence of a second operating condition in a fuel cell stack of the first fuel cell system. 14. The method of claim 11, further comprising: detecting the operating condition. 15. The method of claim 11 wherein the operating condition further comprises at least one selected from a group consisting of a voltage across the power bus, an operating parameter specified by a user, a current on the power bus, a voltage on the power bus, a load condition, a stack current, a stack voltage, a battery current, a battery voltage, a temperature, an ambient hydrogen level, an ambient oxygen level and a reactant flow. 16. The method of claim 11, further comprising: generating a signal in response to detecting the operating condition. 17. The method of claim 16, further comprising: communicating the signal generated from a controller that detects the operating condition to the redundancy switch such that the redundancy switch is opened. 18. The method of claim 11, further comprising: detecting the operating condition in the second fuel cell stack. 19. The method of claim 18 wherein the operating condition in the second fuel cell stack is a fault. 20. The method of claim 18 wherein the operating condition in the second fuel cell stack is a failure. 21. A system for operating an electric power plant having at least a first fuel cell system comprising a first fuel cell stack, an electrical power storage device electrically coupled in parallel with the first fuel cell stack, and a first switch to couple the first fuel cell system to a power bus; a second fuel cell system comprising a second fuel cell stack, another electrical power storage device electrically coupled in parallel with the second fuel cell stack, and a second switch to couple the second fuel cell system to the power bus; wherein the first fuel cell system further comprises a redundancy switch in series with the first switch and the power bus, comprising: means for closing the first switch and the redundancy switch of the first fuel cell system to electrically couple the first fuel cell system to the power bus, wherein the redundancy switch is selectively operable according to at least one of an operating condition of at least the second fuel cell system, a voltage across the power bus, a desired output of a power supply system and a desired nominal current output of the power supply system. 22. The system of claim 21, further comprising: means for detecting one of a fault or a failure in the second fuel cell stack such that the first switch is opened. 23. The system of claim 21, further comprising: means for detecting the operating condition, wherein the other operating condition comprises at least one selected from a group consisting of a voltage across the power bus, an operating parameter specified by a user, a current on the power bus, the voltage on the power bus, a load condition, a stack current, a stack voltage, a battery current, a battery voltage, a temperature, an ambient hydrogen level, an ambient oxygen level and a reactant flow.