System for providing assured power to a critical load

A power system (8) for providing substantially continuous electric power to at least a critical load (14), comprising:

• a. a utility grid power source (10) providing sufficient power to supply the critical load (14);
• b. at least one fuel cell power plant (18) operating substantially continuously for providing at least sufficient power to supply the critical load (14), the at least one fuel cell power plant (18) including a power conditioning system (PCS) for configuring operation of the respective fuel cell (18) in a grid connected mode or in a grid independent mode in response to mode control signals (D1/401′, D2/402′), the at least one fuel cell power plant (18) being normally substantially continuously connected and providing power to, the critical load (14);
• c. a static switch (19) for selectively connecting and disconnecting the grid power source (10) to the at least one fuel cell power plant (18) and to the critical load (14);
• d. a switch controller (49, 45) for controlling the state of the static switch (19) to connect the grid power source (10) with the critical load (14) and the at least one fuel cell power plant (18) during normal operation of the grid power source (10) and to disconnect, within a 4 millisecond interval, the grid power source (10) from the critical load (14) and the at least one fuel cell power plant (18) when the grid power source deviates beyond a limit from normal;
• and
• e. a site management controller (31) connected between the switch controller (49, 45) and the power conditioning system (PCS) and responsive to preliminary mode signals (M1/401, M2/402) from the switch controller (49, 45) for providing the mode control signals (D1/401′, D2/402′) to the fuel cell power conditioning system (PCS) to cause the at least one fuel cell power plant (18) to rapidly transition operation, within a 4 millisecond interval, between the grid connected mode and the grid independent mode.

A power system (8) for providing substantially continuous electric power to at least a critical load (14), comprising:

• a. a utility grid power source (10) providing sufficient power to supply the critical load (14);
• b. at least one fuel cell power plant (18) operating substantially continuously for providing at least sufficient power to supply the critical load (14), the at least one fuel cell power plant (18) including a power conditioning system (PCS) for configuring operation of the respective fuel cell (18) in a grid connected mode or in a grid independent mode in response to mode control signals (D1/401′, D2/402′), the at least one fuel cell power plant (18) being normally substantially continuously connected and providing power to, the critical load (14);
• c. a static switch (19) for selectively connecting and disconnecting the grid power source (10) to the at least one fuel cell power plant (18) and to the critical load (14);
• d. a switch controller (49, 45) for controlling the state of the static switch (19) to connect the grid power source (10) with the critical load (14) and the at least one fuel cell power plant (18) during normal operation of the grid power source (10) and to disconnect, within less than an 8.3 millisecond interval, the grid power source (10) from the critical load (14) and the at least one fuel cell power plant (18) when the grid power source deviates beyond a limit from normal;
• and
• e. a site management controller (31) connected with the switch controller (49, 45) and the power conditioning system (PCS) and responsive to the switch controller (49, 45) for providing mode control signals (D1/401′, D2/402′) to the fuel cell power conditioning system (PCS) to cause the at least one fuel cell power plant (18) to rapidly transition operation, within less than an 8.3 millisecond interval, between the grid connected mode and the grid independent mode.