Load shifting control system for commercial refrigeration

• US 6,067,482 A
• Filed: 01/08/1999
• Issued: 05/23/2000
• Est. Priority Date: 01/08/1999
• Status: Expired due to Fees

• Current Assignee: Hussmann Corporation (Panasonic Holdings Corporation)
• Original Assignee: Hussmann Corporation (Panasonic Holdings Corporation)
• Inventors: Shapiro, Doron
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): Bahta, Kidest
• Application Number:
  US09/227,986
• Time in Patent Office: 501 Days
• Field of Search: 700/286, 700/295, 700/276, 307/64, 307/44
• US Class Current: 700/286
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F25B 2400/06 Several compression cycles arranged in parallel
• CPC Class Codes: F25B 2400/075 with parallel compressors
• CPC Class Codes: F25B 2400/22 Refrigeration systems for supermarkets
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: H02J 3/0075 for providing alternative feeding paths between load and source according to economic or energy efficiency considerations, e.g. economic dispatch
• CPC Class Codes: H02J 3/06 Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
• CPC Class Codes: H02J 9/066 characterised by the use of dynamo-electric machines H02J9/08 takes precedence

Abstract

A load shifting control system for selectively allocating a plurality of discrete electrical loads between a first power source and a second power source includes a plurality of transfer switches connected to respective electrical loads and further includes a processor coupled with the transfer switches. The processor is configured to identify presently available combinations of the discrete loads and to select a preferred one of the presently available load combinations as a function of control parameters and/or demand data provided to the processor. The processor is also configured to generate control signals corresponding to the preferred load combination and to communicate the control signals to the transfer switches, which are adapted to effect an allocation of loads between the power sources in accordance with the preferred load combination upon receiving the control signals.

Claims

1. A processor for selecting a specific combination of discrete electrical loads from a plurality of presently available combinations of discrete electrical loads, wherein each presently available combination of discrete electrical loads represents a different allocation of the loads between a first power source and a second power source, said processor comprising:

means for receiving control parameters and/or demand data associated with the discrete loads and the power sources;

memory means for storing the control parameters and/or demand data;

means for calculating a target demand value for the demand on one of said power sources as a function of the control parameters and/or demand data;

means for identifying each of the presently available combinations of discrete electrical loads; and

means for selecting one load combination from said presently available combinations of discrete electrical loads, wherein said selecting means is adapted for calculating a load demand value for each of said presently available combinations of discrete electrical loads which indicates the actual demand for that combination of discrete loads on said one power source, said one combination of discrete loads having the highest load demand value which does not exceed the target demand value.

2. The processor of claim 1 wherein said one power source is the first power source, and the first power source is an electrical utility.

3. The processor of claim 1 wherein said one power source is the second power source, and the target demand value equals the maximum loading capacity of the second power source.

4. The processor of claim 3 wherein the second power source is a generator or a fuel cell.

5. The processor of claim 1 wherein said calculating means is adapted for selecting as a function of the control parameters and/or demand data one of a first operating mode when said second power source is the less expensive source of power and a second operating mode when said first power source is the less expensive source of power.

6. The processor of claim 1 wherein said presently available load combinations include at least one of a first load combination in which all of the loads are connected to the first power source, a second load combination in which all of the loads are connected to the second power source and a third load combination in which at least one load is connected to the first power source and at least one load is connected to the second power source.

7. The processor of claim 1 further comprising means for producing control signals indicating said one load combination.

8. The processor of claim 7 further comprising output means for communicating the control signals to transfer switches connected to respective electrical loads for activating said transfer switches to selectively transfer the loads between said first and second power sources in accordance with the control signals to effect said one load combination.

9. The processor of claim 1 wherein said calculating means is adapted for adjusting the target demand value.

10. The processor of claim 1 wherein said processor is adapted to select a load combination from the presently available load combinations at predetermined intervals.

11. The processor of claim 1 wherein said processor is adapted to select a load combination from the presently available load combinations upon the occurrence of a predetermined event.

12. The processor of claim 11 wherein the predetermined event is a failure of one or more of said power sources.

13. The processor of claim 1 wherein said selecting means is adapted for calculating the demand on the first power source and on the second power source for each of the presently available load combinations.

14. The processor of claim 1 wherein the control parameters include the rate of change of net savings so that a point of diminishing returns for net savings is reflected in the target demand value.

15. The processor of claim 1 wherein said receiving means is adapted to receive demand data from a plurality of transducers associated with the discrete loads, and wherein said transducers may be current transducers or power transducers.

16. The processor of claim 15 wherein the demand data includes real-time demand data.

17. The processor of claim 16 wherein said selecting means is adapted for determining the demand for each discrete load as a function of real-time demand data.

18. The processor of claim 1 wherein the receiving means is adapted to receive demand data from power transducers associated with the first and second power sources.

19. The processor of claim 1 wherein one or more of said discrete loads are compressors in a refrigeration system.

20. The processor of claim 1 wherein the first power source and the second power source are electrically isolated from and independent of one another.

21. The processor of claim 1 wherein the first power source is a public utility and wherein the control parameters include the rates charged by the public utility, the demand for each of the discrete loads and the maximum loading capacity of the second power source.

22. A control system for selectively allocating a plurality of discrete electrical loads between a first power source and a second power source, said control system comprising:

a plurality of transfer switches connected to respective electrical loads, said transfer switches being operable between a first position in which the load is connected to the first power source and disconnected from the second power source and a second position in which the load is disconnected from the first power source and connected to the second power source; and

a processor coupled with the plurality of transfer switches, said processor being configured to identify presently available combinations of said discrete electrical loads and to select a preferred one of said presently available load combinations as a function of control parameters and/or demand data provided to the processor, wherein said processor is configured to generate control signals corresponding to the preferred load combination and is further configured to communicate the control signals to said transfer switches;

wherein the transfer switches are adapted to effect an allocation of loads between the first and second power sources in accordance with the preferred load combination upon receiving said control signals.

23. The control system of claim 22 further comprising a first power circuit including the first power source and any loads connected to transfer switches disposed in said first position, and further comprising a second power circuit including the second power source and any loads connected to transfer switches disposed in said second position.

24. The control system of claim 22 wherein the first power source and the second power source are electrically isolated from and independent of one another.

25. The control system of claim 22 further comprising a plurality of current transducers adapted to provide demand data to the processor, wherein each of said transducers is associated with one of said discrete electrical loads.

26. The control system of claim 22 further comprising a plurality of power transducers adapted to provide demand data to the processor, wherein each of said transducers is associated with one of said discrete electrical loads.

27. The control system of claim 22 further comprising a first transducer associated with the first power source and a second transducer associated with the second power source for providing demand data to the processor.

28. The control system of claim 22 wherein one or more of said discrete loads are compressors in a refrigeration system.

29. The control system of claim 22 wherein the first power source is a public utility, and wherein the control parameters include the rates charged by the public utility, the demand for each of the discrete loads and the maximum loading capacity of the second power source.

30. The control system of claim 28 wherein the second power source is a generator or a fuel cell.

31. A method for selecting a combination of discrete electrical loads from a plurality of presently available combinations of discrete electrical loads, wherein each presently available combination of discrete electrical loads represents a different allocation of the discrete loads between a first power source and a second power source, said method comprising:

providing control parameters and/or demand data associated with the discrete loads and the power sources to a processor;

storing the control parameters and/or demand data in a memory associated with the processor;

calculating a target demand value for the demand on one of said power sources as a function of the control parameters and/or demand data;

identifying the presently available combinations of discrete electrical loads; and

selecting one load combination from the presently available combinations of discrete electrical loads by calculating a load demand value for each of the presently available combinations of discrete electrical loads which indicates the actual demand for that combination of discrete electrical loads on said one power source and determining which of the presently available load combinations has the highest load demand value which does not exceed the target demand value.

32. The method of claim 31 wherein said one power source is the first power source, and the first power source is a public utility.

33. The method of claim 31 wherein said one power source is the second power source, and wherein the target demand value equals the maximum loading capacity of the second power source.

34. The method of claim 33 wherein the second power source is a generator or fuel cell.

35. The method of claim 31 wherein said calculating step further comprises selecting, as a function of the control parameters and/or demand data, one of a first operating mode when said second power source is the less expensive source of power and a second operating mode when said first power source is the less expensive source of power.

36. The method of claim 31 further comprising producing control signals indicating the selected load combination.

37. The method of claim 36 further comprising communicating the control signals to a plurality of transfer switches connected to respective electrical loads to effect the selected load combination and operating said transfer switches in response to the control signals to selectively connect the loads between said first and second power sources.

38. A commercial refrigeration system capable of allocating electrical loads in a store between at least two power sources, the system comprising:

a compressor having an associated electrical load when running;

a condenser coupled with said compressor in a first refrigeration system in the store;

an evaporator coupled with said compressor and said condenser in the first refrigeration system, wherein the evaporator is disposed in a product cooling zone for cooling displayed product;

a plurality of electrical loads in the store including the electrical load associated with said compressor;

transfer switch means coupled with said electrical loads, wherein said transfer switch means is adapted for selectively switching at least some of said electrical loads from one of said power sources to another of said power sources; and

a processor coupled with the transfer switch means, said processor being configured to identify a plurality of presently available combinations of said electrical loads and to select a preferred one of said presently available load combinations as a function of control parameters and/or demand data provided to the processor, wherein said processor is configured to generate control signals corresponding to the preferred load combination and is further configured to communicate the control signals to said transfer switch means;

wherein said transfer switch means is adapted to effect an allocation of said electrical loads between the power sources in accordance with the preferred load combination upon receiving said control signals.

39. The commercial refrigeration system of claim 38 further comprising a second compressor having an associated electrical load when running, wherein the electrical loads associated with said second compressor is one of said plurality of electrical loads.

40. The commercial refrigeration system of claim 39 further comprising a second refrigeration system which includes said second compressor.

41. The commercial refrigeration system of claim 39 wherein said first refrigeration system includes said second compressor.

42. The commercial refrigeration system of claim 38 wherein said at least two power sources includes a generator, and wherein one of the control parameters is the maximum loading capacity of the generator.

43. The commercial refrigeration system of claim 38 wherein said at least two power sources includes a fuel cell, and wherein one of the control parameters is the maximum loading capacity of the fuel cell.

44. The commercial refrigeration system of claim 38 wherein said at least two power sources includes a public utility, and wherein the control parameters include the rates charged by the public utility and the demand of each of the discrete loads.

45. The commercial refrigeration system of claim 38 wherein said at least two power sources are electrically isolated from and independent of one another.

46. The commercial refrigeration system of claim 38 further comprising a plurality of transducers associated with said power sources for providing demand data to the processor.

47. The commercial refrigeration system of claim 38 further comprising a plurality of current transducers associated with said electrical loads and adapted to provide demand data to the processor.

48. The commercial refrigeration system of claim 38 further comprising a plurality of power transducers associated with said electrical loads and adapted to provide demand data to the processor.

49. A processor for strategizing a target load combination from a plurality of presently available load combinations, each of which represents a different potential allocation of multiple discrete electrical loads as between first and second power sources;

said processor comprising;

means for receiving and storing control parameters and/or demand data from the discrete electrical loads;

means for identifying each of the presently available combinations of said multiple discrete electrical loads and calculating the load demand value thereof on at least one of said power sources;

means for calculating a target demand value for said one of said power sources as a function of the control parameters and/or demand data; and

means for selecting a target load combination from said presently available combinations of said multiple discrete electrical loads having the highest load demand value that does not exceed the target demand value for said one power source.

50. In combination with a food store having multiple product refrigeration requirements represented by at least two discrete compressor power loads, and having at least two other discrete electrical loads, and having an outside utility power source sufficient to exceed the entire power requirements of the food store, and also having an independent on-site dedicated power source;

the improvement comprising;

a processor control system for selectively re-allocating combinations of said discrete electrical loads between said on-site and outside power sources in response to control parameters and/or demand data, said processor control system comprising;

means for receiving and storing control parameters and/or demand data associated with the discrete electrical loads and the power sources;

means for identifying each of the presently available combinations of said discrete electrical loads and calculating the load demand value associated with each identified combination of discrete electrical loads;

means for calculating a target demand value for at least one of said power sources as a function of the control parameters and/or demand data; and

means for strategizing an optimum electrical load allocation of the presently available discrete electrical loads between said on-site and outside power sources toward achieving operating efficiency and power cost savings.

51. The combination of claim 50 wherein the on-site power source is a generator and the outside power source is an electrical utility.

52. The combination of claim 50 wherein said calculating means is adapted for selecting as a function of the control parameters and/or demand data one of a first operating mode when said on-site power source is the less expensive source of power and a second operating mode when said outside power source is the less expensive source of power.

53. The combination of claim 50 wherein said presently available load combinations include at least one of a first load combination in which all of the loads are connected to the outside power source, a second load combination in which all of the loads are connected to the on-site power source and a third load combination in which at least one load is connected to the outside power source and at least one load is connected to the on-site power source.

54. The combination of claim 50 wherein the processor further comprises means for producing control signals indicating said one load combination, and output means for communicating the control signals to transfer switches connected to respective electrical loads for activating said transfer switches to selectively transfer the loads between said outside and on-site power sources in accordance with the control signals to effect said one load combination.

55. The combination of claim 50 wherein said calculating means is adapted for adjusting the target demand value at predetermined intervals.

56. The combination of claim 50 wherein said selecting means is adapted for calculating a load demand value for each of the presently available load combinations.

57. The combination of claim 50 wherein the control parameters include the rate of change of net savings so that a point of diminishing returns for net savings is reflected in the target demand value.

58. The combination of claim 50 wherein said receiving means is adapted to receive demand data from a plurality of transducers associated with the discrete loads.