Fault tolerance control strategies for multi-kite power generation system

Patent metadata

Field	Value
Publication number	US-9948098-B1
Application number	US-201514986251-A
Country	US
Kind code	B1
Filing date	Dec 31, 2015
Priority date	Dec 31, 2015
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A power distribution system includes at least a ground power unit, an aerial vehicle, and a power station. The ground power unit is configured to convert an input AC power into DC power output, wherein the ground power unit includes at least a first bus, second bus, and a third bus, wherein the first bus is configured to operate at a first voltage level referenced to the third bus, and wherein the second bus is configured to operate at a second voltage level referenced to the third bus that is different from the first voltage level. The aerial vehicle may include a plurality of motor-generators coupled to a respective plurality of turbines, wherein the plurality of motor-generators may be configured to be energized by power received from a tether. The power station may be electrically coupled to at least the first bus, the second bus, and the tether and configured to: (i) selectively energize the tether using the first bus; and (ii) responsive to detecting a fault by at least one motor-generator of the plurality of motor-generators, selectively energize the tether using the second bus and not the first bus.

First claim

What is claimed is:

1. A power distribution system comprising:
a ground power unit configured to convert an input AC power into DC power output, wherein the ground power unit includes at least a first bus, second bus, and a third bus, wherein the first bus is configured to operate at a first voltage level referenced to the third bus, and wherein the second bus is configured to operate at a second voltage level referenced to the third bus that is different from the first voltage level;
an aerial vehicle including a plurality of motor-generators coupled to a respective plurality of turbines, wherein the plurality of motor-generators is configured to be energized by power received from a tether; and
a power station electrically coupled to at least the first bus, the second bus, and the tether, wherein the power station is configured to:
selectively energize the tether using the first bus; and
responsive to detecting a fault by at least one motor-generator of the plurality of motor-generators, selectively energize the tether using the second bus and not the first bus.

2. The power distribution system of claim 1 , wherein the ground power unit is a converter stack comprising a plurality of power converters having DC terminals that are coupled to each other in series.

3. The power distribution system of claim 2 , wherein the first bus is electrically coupled to a first DC terminal of a first power converter of the plurality of power converters, wherein the second bus is electrically coupled to a second DC terminal of a second power converter of the plurality of power converters, and wherein the third bus is electrically coupled to a third DC terminal of a power converter that is not the first power converter of the plurality of power converters.

4. The power distribution system of claim 1 , wherein the power station comprises a switching device that carries out the selective energizing of the tether.

5. The power distribution system of claim 4 , wherein the switching device includes at least one transistor.

6. The power distribution system of claim 1 , wherein the ground power unit further includes a voltage converter configured to generate the second voltage level based on an input from the first bus at the first voltage level.

7. The power distribution system of claim 1 , wherein the power station comprises a controller configured to determine that a fault occurred based on a voltage measurement at the aerial vehicle.

8. A power distribution system comprising:
a ground power unit configured to convert an input AC power into DC power, wherein the ground power unit includes a first bus configured to operate at a first voltage level to a reference bus;
an aerial vehicle including a plurality of motor-generators coupled to a respective plurality of turbines, wherein the plurality of motor-generators is configured to be energized by power received from a tether; and
a power station electrically coupled to the first bus and the tether, wherein the power station includes a power converter that receives power from the first bus and is configured to output a second voltage level to a reference bus via a second bus, and wherein the power station is configured to selectively energize the tether using either the first bus or the second bus responsive to detecting a fault by at least one motor-generator of the plurality of motor-generators.

9. The power distribution system of claim 8 , wherein the power converter is a partially rated power converter.

10. The power distribution system of claim 8 , wherein the power converter is a fully rated power converter.

11. The power distribution system of claim 8 , wherein the ground power unit is a converter stack comprising a plurality of power converters having DC terminals that are coupled to each other in series.

12. The power distribution system of claim 8 , wherein the power station comprises a switching device that carries out the selective energizing of the tether.

13. The power distribution system of claim 12 , wherein the switching device includes at least one transistor.

14. A method comprising:
providing a first power bus configured to operate at a first DC reference voltage by converting AC power from an AC source into DC power;
providing a second power bus configured to operate at a second DC reference voltage that is different from the first DC reference voltage;
energizing a plurality of motor-generators from the first power bus;
determining an operational condition of the plurality of motor-generators; and
based on the determined operational condition being indicative of a fault, energizing the plurality of motor-generators from the second power bus.

15. The method of claim 14 , wherein providing the second power bus comprises converting AC power from the AC source into DC power having the second DC reference voltage.

16. The method of claim 14 , wherein providing the second power bus comprises converting DC power having the first DC reference voltage from the first power bus into DC power having the second DC reference voltage.

17. The method of claim 14 , wherein determining the operational condition of a particular motor-generator of the plurality of motor-generators comprises determining a DC voltage level across the motor-generator, wherein the operational condition is indicative of a fault when the DC voltage level is below a threshold voltage level.

18. The method of claim 14 , wherein determining the operational condition of a particular motor-generator of the plurality of motor-generators comprises determining a rotational velocity of the motor-generator, wherein the operational condition is indicative of a fault when the rotational velocity is below a threshold rotational velocity.

19. The method of claim 14 , wherein determining the operational condition of a particular motor-generator of the plurality of motor-generators comprises determining a temperature of the motor-generator, wherein the operational condition is indicative of a fault when the temperature of the motor-generator exceeds a threshold temperature.

20. The method of claim 14 , wherein energizing the plurality of motor-generators from the second power bus comprises causing a switching device to switch from a first mode to a second mode, wherein the first mode energizes the plurality of motor-generators using the first power bus, and wherein the second mode energizes the plurality of motor-generators using the second power bus.

Assignees

• X Dev Llc

Inventors

• Casey Leo Francis
• Dolan Geoff

Classifications

• B64D2221/00

  Electric power distribution systems onboard aircraft · CPC title

• H02J2105/32

  for aircrafts · CPC title

• H02J7/50

  acting upon multiple batteries simultaneously or sequentially · CPC title

• H02J4/25 Primary

  for transfer of electric power between AC and DC networks, e.g. for supplying the DC section within a load from an AC mains system · CPC title

• H02J3/00 Primary

  Circuit arrangements for AC mains or AC distribution networks · CPC title