Energy storage system

• US 9,780,567 B2
• Filed: 02/19/2015
• Issued: 10/03/2017
• Est. Priority Date: 02/19/2015
• Status: Active Grant

• Current Assignee: Cummins Power Generation IP, Inc.
• Original Assignee: Cummins Power Generation IP, Inc.
• Inventors: Hunt, Michelle, Ayana, Elias M., Palmer, Bradford K.
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Htun, Win
• Application Number:
  US14/626,190
• Publication Number:
  US 20160248263A1
• Time in Patent Office: 957 Days
• Field of Search: 307 64, 307 66, 307 34, 307 23, 307 26, 363137, 363 71, 363 96
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 3/02 using a single network for simultaneous distribution of power at different frequencies; using a single network for simultaneous distribution of ac power and of dc power
• CPC Class Codes: H02J 3/26 Arrangements for eliminating or reducing asymmetry in polyphase networks
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02E 40/50 Arrangements for eliminating or reducing asymmetry in polyphase networks

Abstract

Systems and methods for controlling power flow to and from an energy storage system are provided. One energy storage system includes an energy storage device and a bidirectional inverter configured to control a flow of power into or out of the energy storage device via a plurality of phases. The energy storage system further includes a controller configured to control the bidirectional inverter based on a load condition on one or more phases. The controller is configured to control the bidirectional inverter to store power generated by a generator set in the energy storage device and transmit power from the energy storage device to a load driven by the generator set in response to detecting a load imbalance between the phases.

Claims

1. An energy storage system comprising:

an energy storage device;

a bidirectional inverter configured to control a flow of power into or out of the energy storage device via a plurality of phases; and

a controller configured to control the bidirectional inverter based on a load condition on one or more of the plurality of phases, wherein the controller is configured to control the bidirectional inverter to store power generated by a generator set in the energy storage device and transmit power from the energy storage device to a load driven by the generator set in response to detecting a load imbalance between the plurality of phases, and wherein the controller is further configured to;

detect the load imbalance upstream of a local power grid on a first phase of the plurality of phases;

transmit a signal to a transfer switch configured to disconnect the first phase of the local power grid from a power grid upstream of the local power grid in response to receiving the signal while maintaining connections of at least one other phase of the plurality of phases; and

provide power on the first phase using power from the energy storage device or one or more second phases of the plurality of phases.

2. The energy storage system of claim 1, wherein the bidirectional inverter is configured to independently control the flow of power into or out of the energy storage device for each of the plurality of phases.

3. The energy storage system of claim 2, wherein the bidirectional inverter comprises separate single-phase inverter for each of the plurality of phases.

4. The energy storage system of claim 3, further comprising a second energy storage device coupled to each single-phase inverter and configured to temporarily store power received from one or more first phases having a lower applied load than an applied load of one or more second phases before the power is transmitted to the load via the one or more second phases, wherein the second energy storage device comprises at least one of a battery or a supercapacitor.

5. The energy storage system of claim 1, wherein the controller is configured to:

detect a first phase of the plurality of phases having a different load than one or more second phases of the plurality of phases; and

control an operational state of the bidirectional inverter to store power in or transmit power from the energy storage device via the first phase in response to detecting the different load on the first phase.

6. The energy storage system of claim 5, wherein the controller is configured to:

detect a lower load on the first phase than on the one or more second phases; and

control the bidirectional inverter to charge the energy storage device with power generated by the generator set in response to detecting the lower load on the first phase.

7. The energy storage system of claim 5, wherein the controller is configured to:

detect a higher load on the first phase than on the one or more second phases; and

control the bidirectional inverter discharge power from the energy storage device to drive the load on the first phase in response to detecting the higher load on the first phase.

8. The energy storage system of claim 1, wherein the controller is configured to:

receive a plurality of current signals from one or more current sensors, wherein each of the plurality of current signals indicates a current flow on one of the plurality of phases; and

monitor the load condition and detect the load imbalance using the current signals.

9. The energy storage system of claim 1, wherein the controller is configured to:

monitor a voltage for each of the plurality of phases; and

monitor the load condition and detect the load imbalance using the voltages for the plurality of phases.

10. The energy storage system of claim 1, wherein the controller is configured to:

determine a characteristic of the generator set; and

control the bidirectional inverter to store power generated by the generator set in the energy storage device and transmit power from the energy storage device to the load based on the characteristic of the generator set and the load condition and prevent a first phase of the plurality of phases from overloading.

11. The energy storage system of claim 1, wherein the generator set comprises a first generator set of a plurality of generator sets configured to drive a plurality of loads, and wherein the controller is configured to control the bidirectional inverter to store power generated by the generator sets in the energy storage device and transmit power from the energy storage device to the loads in response to detecting a load imbalance between the plurality of phases.

12. The energy storage system of claim 11, wherein the controller is configured to control the bidirectional inverter to balance the load on the plurality of phases while the generator sets are charging at least one of one or more electric vehicles, one or more plug-in hybrid vehicles, or a plurality of removable batteries.

13. A method of controlling a flow of power to and from an energy storage system, the method comprising:

determining, at a controller of the energy storage system, a load condition on one or more of a plurality of phases of a local alternating current (AC) grid; and

controlling a bidirectional inverter of the energy storage system to store power from the local AC grid in an energy storage device of the energy storage system and transmit power from the energy storage device to a load driven by the local AC grid in response to detecting a load imbalance between the plurality of phases;

transmitting a signal to a transfer switch configured to disconnect a first phase of the local AC grid from a utility grid upstream of the local AC grid in response to receiving the signal while maintaining connections of at least one other phase of the plurality of phases; and

providing power on the first phase using power from the energy storage device or one or more second phases of the plurality of phases.

14. The method of claim 13, further comprising independently controlling the flow of power into or out of the energy storage device for each of the plurality of phases using the bidirectional inverter.

15. The method of claim 13, further comprising:

detecting a first phase of the plurality of phases having a different load than one or more second phases of the plurality of phases; and

controlling an operational state of the bidirectional inverter to store power in or transmit power from the energy storage device via the first phase in response to detecting the different load on the first phase.

16. The method of claim 15, wherein:

detecting a lower load on the first phase than on the one or more second phases; and

controlling the bidirectional inverter to charge the energy storage device with power from the first phase in response to detecting the lower load on the first phase.

17. The method of claim 15, wherein:

detecting a higher load on the first phase than on the one or more second phases; and

controlling the bidirectional inverter discharge power from the energy storage device to drive the load on the first phase in response to detecting the higher load on the first phase.

18. The method of claim 13, further comprising:

controlling the bidirectional inverter to balance the load on the plurality of phases by increasing the load on one or more first phases of the plurality of phases in response to detecting the one or more first phases have a lower load than one or more second phases of the plurality of phases; and

charging at least one of one or more electric vehicles, one or more plug-in hybrid vehicles, or a plurality of removable batteries with the power scavenged by the bidirectional inverter by balancing the load on the plurality of phases.

19. The method of claim 13, further comprising:

storing power in the energy storage device coupled to the bidirectional inverter from one or more first phases having a lower applied load than one or more second phases; and

transmitting power from the energy storage device to the one or more second phases;

wherein the energy storage device comprises at least one of a battery or a supercapacitor.

20. The method of claim 13, further comprising:

determining a characteristic of the generator set; and

controlling the bidirectional inverter to store power generated by the generator set in the energy storage device and transmit power from the energy storage device to the load based on the characteristic of the generator set and the load condition and prevent a first phase of the plurality of phases from overloading.

21. A hybrid generator system comprising:

a generator set configured to generate power to drive a load; and

an energy storage system comprising;

an energy storage device;

a bidirectional inverter configured to control a flow of power into or out of the energy storage device via a plurality of phases; and

a controller configured to control the bidirectional inverter based on a load condition on one or more of the plurality of phases, wherein the controller is configured to control the bidirectional inverter to store power generated by the generator set in the energy storage device and transmit power from the energy storage device to the load in response to detecting a load imbalance between the plurality of phases, and wherein controller is further configured to;

detect the load imbalance upstream of a local power grid on a first phase of the plurality of phases;

transmit a signal to a transfer switch configured to disconnect the first phase of the local power grid from a power grid upstream of the local power grid in response to receiving the signal while maintaining connections of at least one other phase of the plurality of phases; and

provide power on the first phase using power from the energy storage device or one or more second phases of the plurality of phases.

22. The hybrid generator system of claim 21, wherein the bidirectional inverter is configured to independently control the flow of power into or out of the energy storage device for each of the plurality of phases.

23. The hybrid generator system of claim 21, wherein the controller is configured to:

detect the first phase of the plurality of phases having a different load than one or more second phases of the plurality of phases; and

control an operational state of the bidirectional inverter to store power in or transmit power from the energy storage device via the first phase in response to detecting the different load on the first phase.

24. The hybrid generator system of claim 23, wherein the controller is configured to:

detect a lower load on the first phase than on the one or more second phases; and

control the bidirectional inverter to charge the energy storage device with power generated by the generator set in response to detecting the lower load on the first phase.

25. The hybrid generator system of claim 23, wherein the controller is configured to:

detect a higher load on the first phase than on the one or more second phases; and

control the bidirectional inverter discharge power from the energy storage device to drive the load on the first phase in response to detecting the higher load on the first phase.

26. The hybrid generator system of claim 21, wherein the controller is configured to:

determine a characteristic of the generator set; and

control the bidirectional inverter to store power generated by the generator set in the energy storage device and transmit power from the energy storage device to the load based on the characteristic of the generator set and the load condition and prevent a first phase of the plurality of phases from overloading.