ALTERNATIVE-SOURCE ENERGY MANAGEMENT

• US 20090027932A1
• Filed: 05/08/2008
• Published: 01/29/2009
• Est. Priority Date: 05/08/2007
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Haines, Lance P., Deokar, Vishwas M.
• Granted Patent: US 7,929,327 B2
• Time in Patent Office: Days
• US Class Current: 363/95
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: Y02B 10/70 Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

A power converter system includes a power converter system including: a DC-to-AC power converter; a first output configured to be coupled to a power grid; a first input configured to be coupled to the power grid; second outputs each configured to be coupled to a corresponding AC load; a power-grid switch coupled to the converter and to the first output; load switches coupled to the converter, the second outputs, and the first input; and a controller coupled to the load switches and to the first output and configured to determine whether energy from the power grid satisfies at least one criterion, the controller being further configured to control the power-grid switch and the load switches to couple the converter to the first output and to couple the first input to the second outputs if the at least one criterion is satisfied and otherwise to control the power-grid switch and the load switches to isolate the converter from the first output and to couple the converter to at least one of the second outputs.

Claims

1. A power converter system comprising:

a DC-to-AC power converter;

a first output configured to be coupled to a power grid;

a first input configured to be coupled to the power grid;

a plurality of second outputs each configured to be coupled to a corresponding AC load;

a power-grid switch coupled to the converter and to the first output;

a plurality of load switches coupled to the converter, the second outputs, and the first input; and

a controller coupled to the load switches and to the first output and configured to determine whether energy from the power grid satisfies at least one criterion, the controller being further configured to control the power-grid switch and the load switches to couple the converter to the first output and to couple the first input to the second outputs if the at least one criterion is satisfied and otherwise to control the power-grid switch and the load switches to isolate the converter from the first output and to couple the converter to at least one of the second outputs.

2. The system of claim 1 wherein the controller is configured to provide a mode indication signal to the converter depending upon whether the at least one criterion is satisfied.

3. The system of claim 2 wherein the converter is configured to operate in a CSI mode or in a VSI mode in accordance with the mode indication signal received from the controller.

4. The system of claim 3 wherein in the CSI mode the converter is configured to provide energy at the voltage of the first output with a corresponding current according to an amount of power available from the converter, and wherein in the VSI mode the converter is configured to provide energy at a predetermined voltage with a current determined by the AC loads coupled to the second outputs.

5. The system of claim 4 wherein the predetermined voltage is approximately the same as a voltage provided by the power grid when the power grid is operational.

6. The system of claim 1 wherein the at least one criterion comprises at least one of an acceptable range of voltage and an acceptable range of frequency.

7. The system of claim 1 wherein the controller is further configured to determine that the system is not unintentionally islanding.

8. The system of claim 1 wherein the controller is coupled to the second outputs and is configured to control the AC load switches to change a distribution of power provided by the converter to portions of the second output if power provided to the second outputs is above an amount of power available to the converter.

9. The system of claim 8 wherein the controller is configured to cause the AC load switch associated with the lowest-priority, presently-connected, non-delayable AC load to isolate the converter from the corresponding second output if the power provided to the second outputs is above the amount of power available to the converter.

10. The system of claim 1 wherein the load switches are configured to be positioned in a first state connecting the second outputs to the converter, in a second state connecting the second outputs to the first input, and in a third state connecting the second outputs to neither the converter nor the first input.

11. The system of claim 1 further comprising a second input configured to be coupled to an AC power source separate from the power grid wherein the load switches are further coupled to the second input.

12. The system of claim 11 wherein the load switches are configured to be positioned in a first state connecting the second outputs to the converter, in a second state connecting the second outputs to the first input, in a third state connecting the second outputs to the second input, and in a fourth state connecting the second outputs to neither the converter nor the first input nor the second input.

13. A power converter system comprising:

a first input configured to receive a DC voltage from a first DC power source;

a second input configured to couple to a power grid;

a first output configured to couple to the power grid;

a plurality of second outputs each configured to couple to a corresponding AC load;

a power routing module coupled to the first output and the second outputs; and

a DC-to-AC converter coupled to the first input and the power routing module, the converter being configured to selectively operate in either a first or second mode, in the first mode the converter acting as a current source to convert the DC voltage received from the first input and to provide an AC current to the power routing module, and in the second mode the converter acting as a voltage source to convert the DC voltage received from the first input and to provide an AC voltage of a predetermined level.

14. The system of claim 13 wherein the converter is configured to effect the first and second modes in response to a first indication that the power grid is connected to the first output and in an acceptable state and an unacceptable state, respectively.

15. The system of claim 14 further comprising a controller coupled to the first output and the converter and configured to determine at least one of whether a voltage from the power grid is acceptable, whether a frequency of energy from the power grid is acceptable, and whether the system is unintentionally islanding, and to provide the first indication to the converter.

16. The system of claim 15 wherein the controller is coupled to the power routing module and configured to provide a second indication of an acceptability of energy received by the system from the power grid, and the power routing module is configured to route energy from the converter to the first output if the received grid energy is acceptable and to selectively route energy from the converter to the second outputs if the received grid energy is unacceptable.

17. The system of claim 16 wherein the power routing module is coupled and configured to selectively route energy from the second input to the second outputs if the received grid energy is acceptable.

18. The system of claim 13 further comprising a DC disconnect module coupled to the first input and configured to be manually operated to selectively connect/disconnect a DC voltage source to/from the converter.

19. The system of claim 13 further comprising a third input configured to couple to an AC power source separate from the power grid.

20. The system of claim 13 further comprising:

a second DC power source comprising an energy storage device; and

a bidirectional DC-to-DC converter coupled to the energy storage device and to the DC-to-AC converter.

21. A power converter system comprising:

a DC-to-AC power converter configured to receive DC power from at least one DC power source;

a grid switch coupled to the converter and configured to couple to a power grid;

a plurality of selective couplings coupled to the converter, the selective couplings including load lines configured to be coupled to AC loads, the selective couplings being configured to selectively couple the converter to the load lines; and

a controller coupled to the selective couplings and configured to be coupled to the power grid, the controller being configured to determine whether energy from the power grid satisfies at least one criterion and to control the grid switch to isolate the converter from the power grid, and to control the selective couplings to couple the converter to at least one of the load lines, if the at least one criterion is unsatisfied, the controller being further configured to control the selective couplings to change a distribution of power provided by the converter to the load lines if power provided to the load lines is above an amount of power available to the converter.

22. The system of claim 21 wherein the controller is configured to cause the selective couplings to change a distribution of power provided by the converter to the load lines dependent upon at least one criterion other than power drawn on the load lines.

23. The system of claim 22 wherein the controller is configured to cause the selective coupling associated with a presently-connected, lowest-priority, non-delayable AC load to isolate the converter from the respective load line if power provided to the load lines is above an amount of power available to the converter.

24. The system of claim 21 further comprising an energy storage module coupled to the converter and the controller, wherein the controller is configured to disconnect a presently-connected delayable load from the converter before attempting to use energy from the energy storage module to power presently-connected loads if power available from the converter from the at least one solar panel is insufficient to power the presently-connected loads.

25. The system of claim 21 wherein each of the selective couplings are configured to be positioned in a first state connecting a respective one of the load lines to the converter, in a second state connecting a respective one of the load lines to the power grid, and in a third state connecting a respective one of the load lines to neither the converter nor the power grid.

26. The system of claim 21 wherein the selective couplings are further configured to couple to an AC power source separate from the power grid.

27. The system of claim 26 wherein each of the selective couplings are configured to be positioned in a first state connecting a respective one of the load lines to the converter, in a second state connecting a respective one of the load lines to the power grid, in a third state connecting a respective one of the load lines to the AC power source, and in a fourth state connecting a respective one of the load lines to neither the converter nor the power grid nor the AC power source.

28. The system of claim 21 wherein the DC-to-AC power converter is configured to receive DC power from a first DC power source through a unidirectional connection, the system further comprising:

a second DC power source comprising an energy storage device; and

a bidirectional DC-to-DC converter coupled to the energy storage device and to the DC-to-AC power converter.

29. The system of claim 21 wherein the controller is configured to connect and disconnect loads to and from the converter based upon permitted sources of power for respective loads.

30. A power converter system comprising:

a DC-to-AC power converter;

a plurality of outputs each configured to be coupled to an AC load;

a plurality of load switches coupled to the converter and the outputs; and

a controller coupled to the load switches and to the outputs and configured to control the load switches to selectively couple the converter to the outputs to selectively provide AC power from the DC-to-AC power converter to the outputs dependent upon at least one characteristic associated with the outputs other than power drawn on the outputs.

31. The system of claim 30 further comprising a first DC source that is unidirectionally coupled to the DC-to-AC power converter to supply DC power to the DC-to-AC power converter, the system further comprising:

a second DC source comprising an energy storage device; and

a bidirectional DC-to-DC converter coupled to the energy storage device and to the DC-to-AC power converter.

32. The system of claim 30 further comprising a bidirectional DC-to-DC converter coupled to the DC-to-AC converter and configured to couple to an energy storage device.

33. The system of claim 30 wherein the first DC source comprises at least one of a DC-output generator and at least one solar panel.

34. The system of claim 30 wherein the at least one characteristic is at least one of whether a particular output is permitted to receive power from a particular source, and whether a particular output is associated with a delayable AC load.

35. The system of claim 30 further comprising an AC generator coupled to the load switches.

36. A method of regulating power delivery by a power delivery system, the method comprising:

determining whether a power grid with acceptable first AC power available is connected to the power delivery system;

receiving first DC power at a DC-to-AC converter from a first DC power source other than an energy storage device and converting the received first DC power from the first DC power source to second AC power;

providing the second AC power to the power grid if it is determined that a power grid with acceptable power available is connected to the power delivery system; and

providing the second AC power to a first AC load, of a plurality of AC loads, connected to the power delivery system if it is determined that no power grid with acceptable power available is connected to the power delivery system;

wherein the second AC power is provided to the first AC load dependent upon at least one characteristic of the first AC load in addition to power draw of the AC load.

37. The method of claim 36 wherein the at least one characteristic comprises delayability of the respective load.

38. The method of claim 36 wherein the at least one characteristic comprises permission of the respective load to receive power derived from the first DC source.

39. The method of claim 36 wherein providing the second AC power to the first AC load comprises providing the second AC power in an amount only up to a threshold amount.

40. The method of claim 36 further comprising providing third AC power to a second AC load of the AC loads dependent upon whether the second AC load is permitted to receive power derived from a source of the third AC power.

41. The method of claim 40 further comprising receiving second DC power at the DC-to-AC converter from a second DC power source, comprising an energy storage device, and converting the received second DC power from the second DC power source to the third AC power.

42. The method of claim 40 further comprising receiving the third AC power from an AC generator.

43. The method of claim 42 further comprising:

receiving second DC power at the DC-to-AC converter from a second DC power source, comprising an energy storage device, and converting the received second DC power from the second DC power source to fourth AC power;

receiving fifth AC power from an AC generator; and

combining the fourth and the fifth AC power to form the third AC power.

44. The method of claim 40 wherein the first and second AC loads are physically separate such that the second and third AC powers are provided to physically separate loads.

45. A method of regulating power delivery by a power delivery system, the method comprising:

providing characteristics of AC loads;

providing indications of alternative power sources, which of the alternative power sources are permitted to power which of the AC loads, and priority of use of the alternative power sources, wherein the alternative power sources are connected to the power delivery system, wherein the alternative power sources are different from a power grid; and

powering the at least one of the AC loads using at least one of the alternative power sources, without using a power grid, based on the characteristics of the AC loads, the priority of use of the alternative power sources, and which of the alternative power sources are permitted to power which of the AC loads.

46. The method of claim 45 wherein the characteristics include load delayability.

47. The method of claim 45 wherein the alternative power sources include a source of renewable DC power, the method further comprising:

determining whether a power grid with acceptable AC power available is connected to the power delivery system; and

providing power to the power grid from the source of renewable DC power if it is determined that a power grid with acceptable power available is connected to the power delivery system.

48. The method of claim 45 wherein powering the AC loads comprises powering the AC loads without exceeding a power threshold.

49. The method of claim 45 wherein powering the AC loads comprises discontinuing to power a particular one of the AC loads if a power drawn by the powered loads exceeds an available power presently provided by the alternative power sources to the AC loads.

50. The method of claim 49 wherein the discontinuing comprises selecting the particular one of the AC loads based upon at least one of the load characteristics.

51. The method of claim 49 wherein the discontinuing comprises selecting the particular one of the AC loads based upon the priority of use of the alternative power sources.