Multi-port energy storage system and control method thereof

1. A multi-port energy storage system comprising:

a bidirectional power conversion circuit formed with an AC side and a DC side;

a DC-AC inverter circuit formed with a DC side and an AC side;

an electric energy storage facility connecting between the DC side of the bidirectional power conversion circuit and the DC side of the DC-AC inverter circuit;

a first AC port connecting with the AC side of the bidirectional power conversion circuit;

a second AC port connecting with the AC side of the DC-AC inverter circuit; and

an AC switch formed with a first side connecting with a utility power source or an AC power source and a second side connecting with the AC side of the bidirectional power conversion circuit, with the bidirectional power conversion circuit switching on the AC switch to connect the electric energy storage facility, the first AC port and the second AC port to the utility power source or the AC power source, with the bidirectional power conversion circuit switching off the AC switch to disconnect the electric energy storage facility, the first AC port and the second AC port from the utility power source or the AC power source;

wherein when the utility power source or the AC power source stays within a normal tolerance, the AC switch is selectively switched on as a close state allowing the utility power source or the AC power source to directly supply an AC power to the first AC port and further to directly supply the AC power to the AC side of the bidirectional power conversion circuit, wherein the bidirectional power conversion circuit converts the AC power of the utility power source or the AC power source into a DC power to charge the electric energy storage facility and the DC power is further converted into an AC power by the DC-AC inverter circuit to supply to the second AC port;

wherein when the utility power source or the AC power source stays within the normal tolerance, the AC switch is selectively switched on as a close state allowing the utility power source or the AC power source to directly supply the AC power to the first AC port while the bidirectional power conversion circuit converts the DC power stored in the electric energy storage facility into a first AC power to supply to the utility power source or the AC power source and the DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into a second AC power to supply to the second AC port; and

wherein when the utility power source or the AC power source is out of tolerance is in or failure, the AC switch is selectively switched off as an open state, wherein the bidirectional power conversion circuit converts the DC power stored in the electric energy storage facility into the first AC power to supply to the first AC port and the DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into the second AC power to the second AC port.

2. The multi-port energy storage system as defined in claim 1 , wherein the electric energy storage facility further comprises at least one additional DC-AC inverter circuit to connect with a third AC port.

3. The multi-port energy storage system as defined in claim 1 , wherein the first AC port supplies a utility level of power quality while the second AC port supplies clean and stable power quality whose voltages, frequencies or waveforms are different from those of the utility level of power quality.

4. The multi-port energy storage system as defined in claim 1 , wherein the first AC port connects with a first load while the second AC port connects with a second load.

5. The multi-port energy storage system as defined in claim 1 , wherein a source of the AC power source or the electric energy storage facility comprises solar power, wind power or fuel cells.

6. The multi-port energy storage system as defined in claim 1 , wherein the AC switch is selected from a mechanical device comprising a relay, a magnetic contactor, or a solid-state device comprising a set of anti-parallel thyristors or insulated gate bipolar transistors.

7. A multi-port energy storage system comprising:

a bidirectional power conversion circuit formed with an AC side and a DC side;

a first DC-AC inverter circuit formed with a DC side and an AC side;

a second DC-AC inverter circuit formed with a DC side and an AC side;

an electric energy storage facility connecting between the DC side of the bidirectional power conversion circuit and the DC side of the first DC-AC inverter circuit and the electric energy storage facility further connecting between the DC side of the bidirectional power conversion circuit and the DC side of the second DC-AC inverter circuit;

a first AC port connecting with the AC side of the bidirectional power conversion circuit;

a second AC port connecting with the AC side of the first DC-AC inverter circuit;

a third AC port connecting with the AC side of the second DC-AC inverter circuit; and

an AC switch formed with a first side connecting with a utility power source or an AC power source and a second side connecting with the AC side of the bidirectional power conversion circuit, with the bidirectional power conversion circuit switching on the AC switch to connect the electric energy storage facility, the first AC port, the second AC port and the third AC port to the utility power source or the AC power source, with the bidirectional power conversion circuit switching off the AC switch to disconnect the electric energy storage facility, the first AC port, the second AC port and the third AC port from the utility power source or the AC power source;

wherein when the utility power source or the AC power source stays within a normal tolerance, the AC switch is selectively switched on as a close state allowing the utility power source or the AC power source to supply an AC power to the first AC port and further to directly supply the AC power to the AC side of the bidirectional power conversion circuit, wherein the bidirectional power conversion circuit converts the AC power of the utility power source or the AC power source into a DC power to charge the electric energy storage facility and the DC power is further converted into a first AC power by the first DC-AC inverter circuit to supply to the second AC port or the DC power is further converted into a second AC power by the second DC-AC inverter circuit to supply to the third AC port;

wherein when the utility power source or the AC power source stays within the normal tolerance, the AC switch is selectively switched on as a close state allowing the utility power source or the AC power source to directly supply the AC power to the first AC port while the bidirectional power conversion circuit converts the DC power stored in the electric energy storage facility into a third AC power to supply to the utility power source or the AC power source, and the first DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into a first AC power to supply to the second AC port, or alternatively the second DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into a second AC power to supply to the third AC port; and

wherein when the utility power source or the AC power source is out of tolerance or is in failure, the AC switch is selectively switched off as an open state, wherein the bidirectional power conversion circuit converts the DC power stored in the electric energy storage facility into the third AC power to supply to the first AC port, and the first DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into the first AC power to the second AC port, or alternatively the second DC-AC inverter circuit converts the DC power stored in the electric energy storage facility into the second AC power to supply to the third AC port.

8. The multi-port energy storage system as defined in claim 7 , wherein the electric energy storage facility further comprises at least one additional DC-AC inverter circuit to connect with a fourth AC port.

9. The multi-port energy storage system as defined in claim 7 , wherein the first AC port supplies a utility level of power quality while the second AC port and the third AC port supply clean and stable power quality whose voltages, frequencies or waveforms are different from those of the utility level of power quality.

10. The multi-port energy storage system as defined in claim 7 , wherein the first AC port connects with a first load, the second AC port connects with a second load and the third AC port connects with a third load.

11. The multi-port energy storage system as defined in claim 7 , wherein the AC switch is selected from a mechanical device comprising a relay, a magnetic contactor, or a solid-state device comprising a set of anti-parallel thyristors or insulated gate bipolar transistors.

12. A control method for a multi-port energy storage system comprising:

connecting an energy storage system to a utility power source or an AC power source, with the energy storage system comprising a bidirectional power conversion circuit, a DC-AC inverter circuit, an electric energy storage facility, a first AC port, a second AC port and an AC switch; and

connecting a first side of the AC switch to the utility power source or the AC power source, with further connecting a second side of the AC switch to the AC side of the bidirectional power conversion circuit, with switching on the AC switch to connect the electric energy storage facility, the first AC port and the second AC port to the utility power source or the AC power source, with switching off the AC switch to disconnect the electric energy storage facility, the first AC port and the second AC port from the utility power source or the AC power source;

wherein when the utility power source or the AC power source stays within a normal tolerance, selectively switching on the AC switch as a close state for allowing the utility power source or the AC power source to supply an AC power to the first AC port and further to directly supply the AC power to an AC side of the bidirectional power conversion circuit, with the bidirectional power conversion circuit converting the AC power of the utility power source or the AC power source into a DC power to charge the electric energy storage facility and converting the DC power into an AC power by the DC-AC inverter circuit to supply to the second AC port;

wherein when the utility power source or the AC power source stays within the normal tolerance, selectively switching on the AC switch as a close state for allowing the utility power source or the AC power source to directly supply the AC power to the first AC port while the bidirectional power conversion circuit converts the DC power stored in the electric energy storage facility into a first AC power to supply to the utility power source or the AC power source and with the DC-AC inverter circuit converting the DC power stored in the electric energy storage facility into a second AC power to supply to the second AC port; and

wherein when the utility power source or the AC power source is out of tolerance or failure, selectively switching off the AC switch as an open state, with the bidirectional power conversion circuit converting the DC power stored in the electric energy storage facility into the first AC power to supply to the first AC port and with the DC-AC inverter circuit converting the DC power stored in the electric energy storage facility into the second AC power to the second AC port.

13. The control method for the multi-port energy storage system as defined in claim 12 , wherein the first AC port supplies a utility level of power quality while the second AC port supplies clean and stable power quality whose voltages, frequencies or waveforms are different from those of the utility level of power quality.

14. The control method for the multi-port energy storage system as defined in claim 12 , wherein the first AC port connects with a first load while the second AC port connects with a second load.

15. The control method for the multi-port energy storage system as defined in claim 12 , wherein the AC switch connects between utility power source or the AC power source and the AC side of the bidirectional power conversion circuit.

16. The control method for the multi-port energy storage system as defined in claim 12 , further comprising connecting at least one additional DC-AC inverter circuit with a third AC port.

17. The control method for the multi-port energy storage system as defined in claim 16 , wherein the third AC port connects with a third load.

18. The control method for the multi-port energy storage system as defined in claim 16 , wherein the third AC port supplies clean and stable power quality whose voltages, frequencies or waveforms are different from those of the utility level of power quality.

19. The control method for the multi-port energy storage system as defined in claim 12 , wherein a source of the AC power source or the electric energy storage facility comprises solar power, wind power or fuel cells.

20. The control method for the multi-port energy storage system as defined in claim 12 , wherein the AC switch is selected from a mechanical device comprising a relay, a magnetic contactor, or a solid-state device comprising a set of anti-parallel thyristors or insulated gate bipolar transistors.