Abstract: A distributed electrical power generating and utilizing system includes an induction generator driven by a prime mover requiring reactive power to operate for providing electrical power on a bus. The bus has a gross load and is also connectable to a utility power grid by a switch. The gross load includes at least a non-linear electrical load component, typically including a variable speed device and associated diode rectifier front end. The bus includes a harmonic filter having a power factor-correcting capacitor integrated therewith for collectively compensating harmonic distortion caused by the non-linear load component and for correcting power factor to compensate for reactive power required by at least the inductive generator.

Abstract: An arrangement for monitoring the current or state of charge (SOC) of an energy system (230) having one or more series-connected strings (S1, S2, . . . Sn) of battery cells (C1, C2, . . . Cn). The battery cells each have respective dissipative devices (D1, D2, . . . Dn) selectively connectable in parallel therewith for balancing cell voltages in the string. The dissipative devices are of predetermined, typically equal, impedance value. The voltage across each cell (Vc1, Vc2, . . . Vcn) may be separately monitored, such that by dividing the monitored voltage across a cell by the impedance value of a dissipative device connected in parallel therewith, the dissipative current is determined. A summation of all of the dissipative currents yields an error value, which error value is then removed from the measured gross current (Ibat) flowing through the combined battery cells and dissipative devices to yield a corrected value of current (Ibatnet). A corrected SOC value (Qnet) is obtainable in a similar manner.

Abstract: A power system (110; 210; 310) combines a power source (14) having a DC output (20A, 20B) with an AC supply from the AC grid (12) to provide AC to customer's loads (16) and DC to various DC auxiliary loads (134, 134A). The DC output of the DC power source (14) is connected in steady-state to the DC input (120A, 120B, 60) of a converter/bi-directional inverter (122; 222) for conversion therein to AC for connection (124, 124A, 32) to the customer's loads (16) and (124, 124B) to any AC auxiliary loads (134, 234). During start-up of the DC power source (14), an open isolation switch (70) disconnects that DC power source (14) from the bi-directional inverter (122; 222). A start-up power supply (50, 60; 250, 60; 90, 180, 60) selectively connects (56; 94) between the AC power grid (12) and the bi-directional inverter (122; 222) and/or DC controllers (134A) to provide a supply of rectified DC power at the inverter DC input and to certain DC auxiliary loads (134, 234).

Abstract: During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.

Abstract: During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.

Abstract: A distributed electrical power generating and utilizing system includes an induction generator driven by a prime mover requiring reactive power to operate for providing electrical power on a bus. The bus has a gross load and is also connectable to a utility power grid by a switch. The gross load includes at least a non-linear electrical load component, typically including a variable speed device and associated diode rectifier front end. The bus includes a harmonic filter having a power factor-correcting capacitor integrated therewith for collectively compensating harmonic distortion caused by the non-linear load component and for correcting power factor to compensate for reactive power required by at least the inductive generator.

Abstract: During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.

Abstract: A power system (110; 210; 310) combines a power source (14) having a DC output (20A, 20B) with an AC supply from the AC grid (12) to provide AC to customer's loads (16) and DC to various DC auxiliary loads (134, 134A). The DC output of the DC power source (14) is connected in steady-state to the DC input (120A, 120B, 60) of a converter/bi-directional inverter (122; 222) for conversion therein to AC for connection (124, 124A, 32) to the customer's loads (16) and (124, 124B) to any AC auxiliary loads (134, 234). During start-up of the DC power source (14), an open isolation switch (70) disconnects that DC power source (14) from the bi-directional inverter (122; 222). A start-up power supply (50, 60; 250, 60; 90, 180, 60) selectively connects (56; 94) between the AC power grid (12) and the bi-directional inverter (122; 222) and/or DC controllers (134A) to provide a supply of rectified DC power at the inverter DC input and to certain DC auxiliary loads (134, 234).

Abstract: An arrangement for monitoring the current or state of charge (SOC) of an energy system (230) having one or more series-connected strings (S1, S2, . . . Sn) of battery cells (C1, C2, . . . Cn). The battery cells each have respective dissipative devices (D1, D2, . . . Dn) selectively connectable in parallel therewith for balancing cell voltages in the string. The dissipative devices are of predetermined, typically equal, impedance value. The voltage across each cell (Vc1, Vc2, . . . Vcn) may be separately monitored, such that by dividing the monitored voltage across a cell by the impedance value of a dissipative device connected in parallel therewith, the dissipative current is determined. A summation of all of the dissipative currents yields an error value, which error value is then removed from the measured gross current (Ibat) flowing through the combined battery cells and dissipative devices to yield a corrected value of current (Ibatnet). A corrected SOC value (Qnet) is obtainable in a similar manner.

Abstract: Fuel cell stack assemblies (15, 16) connected in parallel through related power control portions (39, 40; 60, 61) of a system power converter (41) supply power to a common grid (22) or non-grid load (58) on an equal or near-equal current basis. Power command to one portion is one-half the total power (P*) minus a function (46) of the difference (45) in current from the stack assemblies. The other portion power command (P1*) for a utility grid (22) is the difference between the total power and the power command (P2*) to the first stack assembly. For a non-grid load, one portion (61) controls the load voltage, the other portion command (P2*) causes substantially equal currents. Altering (33b) actual current signals results in the cell stack assemblies providing different currents. A failed stack assembly is disconnected from the load and reactant; the non-failed assembly having an appropriate power command.

Abstract: A fuel cell stack (7) with output lines (8, 9) has a bank of supercapacitors (10) or batteries (10a) connected across the output lines, either directly or through a DC/DC converter (22). The fuel cell stack receives fuel either from a reformer (13) or a source (13a) of hydrogen. Power is supplied through a power conditioning system (15) to a load (16), all under the control of a controller (19). The supercapacitors or batteries receive additional charge from excess power when there is a sudden decrease in the load, and provide charge to the output power lines (8, 9) when there is a sudden increase in load demand. In one embodiment, the voltage of the supercapacitors or batteries always follow the voltage of the fuel cell stack, thereby providing or receiving commensurate charge. With the DC/DC converter, the supercapacitors or batteries may be operated at voltages which are a multiple or a fraction of fuel cell stack voltage, and may have voltages boosted or bucked to aid in response to transients.

Abstract: A prime mover (28) in a heat recovery system drives an induction generator (8) which feeds power to a utility grid (9) through a breaker (10) but also powers a load including auxiliary induction motors (11, 12). To provide acceptable waveform and power factor, the auxiliary equipment is driven through IGBT switched bridge converters (13) by DC voltage (15) generated by an IGBT switched bridge converter (13a), instead of three-phase diode rectifiers (16). The switched bridge converter controller (14a) is responsive to a system process controller (23a) which causes the switched bridge controller (13a) to be driven in response to the voltage (26) and current (27) on the generator bus (17). This eliminates the need for harmonic filters (18) and power factor capacitors (20) while improving the quality of the power generated. The controller (23a) trips the breaker if the voltage, frequency or power factor is out of limits.

Abstract: During startup or shutdown of a fuel cell power plant, the electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.