Abnormality Detection Architecture and Methods For Photovoltaic Systems

• US 20130307556A1
• Filed: 01/23/2012
• Published: 11/21/2013
• Est. Priority Date: 01/21/2011
• Status: Active Grant

• Current Assignee: Ampt, LLC
• Original Assignee: Ampt, LLC
• Inventors: Ledenev, Anatoli, Porter, Robert M., Fuller, Wesley R.
• Granted Patent: US 9,366,714 B2
• Time in Patent Office: Days
• US Class Current: 324/509
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02S 50/10 Testing of PV devices, e.g. of PV modules or single PV cells testing of semiconductor devices during manufacturing H01L22/00
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

One aspect of the inventive technology disclosed herein, in certain embodiments, may involve the determination of at least one measured, instantaneous intra-string current difference for each of the power generating string, and the use of such determinations to assess the existence of leakage current, a frequent ground fault predecessor, thereby enabling preclusion of a ground fault that would otherwise result. Certain methods and detection architecture may enable precise abnormality location, e.g., enabling the identification of which solar module assembly in particular is faulty. Another aspect relates generally, in certain embodiments, to detection circuit architecture operable to sequentially impress a leakage current inducing voltage upon each rail of a photovoltaic system. Another relates generally, in certain embodiments, to the use of at least one current interrupter at each end of a string to preclude flow therethrough in the event of e.g., unintended field reversal.

Claims

1. A method of detecting operational abnormality within a solar power array that comprises at least one power generating string, said at least one power generating string comprising a plurality of serially connected solar module assemblies, said method comprising the steps of:

determining at least one measured, instantaneous intra-string current difference for each of said at least one power generating string,

wherein each of said at least one measured, instantaneous intra-string current difference is an instantaneous difference in string current between a respective two points on said at least one power generating string;

assessing the presence of said operational abnormality between said respective two points based on said measured, instantaneous intra-string current difference; and

repeating said steps of determining and assessing.

2. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein said step of determining comprises the step of determining at least two measured, instantaneous intra-string current differences for at least one of said at least one power generating string, each of said at least two measured, instantaneous intra-string current differences associated with a different respective two points on said at least one of said at least one power generating string.

3. A method of detecting operational abnormality within a solar power array as described in claim 2 wherein said each of said at least two measured, instantaneous intra-string current differences are associated with a different said serially connected module assembly.

6. A method of detecting operational abnormality within a solar power array as described in claim 2 wherein each of said different respective two points is associated with a different said string connected solar module assembly.

19. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein said step of determining comprises the step of determining a plurality of measured, instantaneous intra-string current differences for at least one of said at least one power generating string.

20. A method of detecting operational abnormality within a solar power array as described in claim 19 wherein said at least one of said at least one power generating string comprises n number of said serially connected solar module assemblies.

21. A method of detecting operational abnormality within a solar power array as described in claim 20 wherein said step of determining comprises the step of determining n number of measured, instantaneous intra-string current differences for said at least one of said at least one power generating string.

22. A method of detecting operational abnormality within a solar power array as described in claim 21 further comprising the step of identifying which particular serially connected module assembly is causing an operational abnormality.

23. A method of detecting operational abnormality within a solar power array as described in claim 21 wherein each of said serially connected solar module assemblies of said at least one of said at least one power generating string includes a converter.

24. A method of detecting operational abnormality within a solar power array as described in claim 23 wherein a majority of the measured, instantaneous intra-string current differences of said at least one of said at least one power generation string is a difference between measured output currents of a respective two neighboring converters.

25. A method of detecting operational abnormality within a solar power array as described in claim 23 wherein said difference between output measured currents of said two neighboring converters is a difference between negative output currents of said respective two neighboring converters.

26. A method of detecting operational abnormality within a solar power array as described in claim 25 wherein the measured, instantaneous intra-string current difference for the serially connected solar module assembly nearest a higher potential rail is determined from measurements of negative converter input current, negative converter output current, converter input voltage, and converter output voltage.

27. A method of detecting operational abnormality within a solar power array as described in claim 23 wherein said difference between output measured currents of said two neighboring converters is a difference between positive output currents of said respective two neighboring converters.

28. A method of detecting operational abnormality within a solar power array as described in claim 27 wherein the measured, instantaneous intra-string current difference for the serially connected solar module assembly nearest a lower potential rail is determined from measurements of positive converter input current, positive converter output current, converter input voltage, and converter output voltage.

30. A method of detecting operational abnormality within a solar power array as described in claim 23 wherein a majority of the respective two points on said at least one of said at least one power generating string are an output current point of said respective two neighboring converters.

31. A method of detecting operational abnormality within a solar power array as described in claim 20 wherein none of said string connected module assemblies of said at least one of said at least one power generating string includes a converter.

34. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein at least one of said at least one power generating string comprises at least two substrings.

40. A method of detecting operational abnormality within a solar power array as described in claim 34 wherein said at least one of said at least one power generating string comprises at least one string converter established as part of each of said at least two substrings.

41. A method of detecting operational abnormality within a solar power array as described in claim 40 wherein said step of determining comprises the step of determining a difference between converter output currents.

46. A method of detecting operational abnormality within a solar power array as described in claim 40 wherein said step of determining comprises the step of determining a difference between converter inputs.

49. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein said step of determining comprises the step of determining two measured, instantaneous intra-string current differences for at least one of said at least one power generating string.

55. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein said step of determining comprises the step of determining at least one high precision, measured, instantaneous intra-string current difference for each of said power generating string.

56. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein the step of assessing comprises the step of assessing the presence of leakage current from within said at least one power generating string.

57. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein the step of assessing comprises the step of assessing the presence of a ground fault within said at least one power generating string.

58. A method of detecting operational abnormality within a solar power array as described in claim 1 wherein said step of assessing comprises the step of assessing the presence of arc of said at least one power generating string.

60. A method of detecting operational abnormality within a solar power array as described in claim 1 further comprising the step of identifying a portion of said solar power array that is causing said operational abnormality.

61. A method of detecting operational abnormality within a solar power array as described in claim 60 further comprising the step of computerized responding in response to an assessment made upon performance of said step of assessing.

62. A method of detecting operational abnormality within a solar power array as described in claim 61 wherein said step of computerized responding comprises the step of isolating said portion of said solar power array that is causing said operational abnormality.

4-5. -5. (canceled)

7-18. -18. (canceled)

29. (canceled)

32-33. -33. (canceled)

35-39. -39. (canceled)

42-45. -45. (canceled)

47-48. -48. (canceled)

50-54. -54. (canceled)

59. (canceled)

63. A solar power circuit operable to detect operational abnormality, said circuit comprising:

a solar power array that itself comprises at least one power generating string, said at least one power generating string comprising a plurality of serially connected solar module assemblies;

at least one measured, instantaneous intra-string current difference determinator for each of said power generating string, each said determinator determining an instantaneous difference in string current between a respective two points on said at least one power generating string;

operational abnormality assessment componentry that acts on data generated by said at least one measured, instantaneous intra-string current difference determinator; and

computerized detected leakage response componentry that is responsive to said operational abnormality assessment componentry.

64. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one measured, instantaneous intra-string current difference determinator comprises a differential current measurer.

65. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one measured, instantaneous intra-string current difference determinator comprises two current measurers, one at a first of said respective two points and another at a second of said respective two points.

66. A solar power circuit operable to detect operational abnormality as described in claim 65 wherein said at least one measured, instantaneous intra-string current difference determinator comprises computerized componentry that compares a current measurement at said first point with a current measurement at said second point.

67. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one solar power generating string comprises no converter.

68. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one solar power generating string comprises only one converter.

69. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one solar power generating string comprises more than one converter.

70. A solar power circuit operable to detect operational abnormality as described in claim 69 wherein said at least one solar power generating string comprises one converter per said serially connected solar module assemblies.

71. A solar power circuit operable to detect operational abnormality as described in claim 70 further comprising measurement componentry configured to measure a converter input current, a converter output current, converter input voltage and converter output voltage of a converter of a serially connected module assembly that is nearest one rail of said at least one solar power generating string of said solar panel array.

72. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one solar power generating string comprises no substrings.

73. A solar power circuit operable to detect operational abnormality as described in claim 63 wherein said at least one solar power generating string comprises a plurality of substrings.

74. A solar power circuit operable to detect operational abnormality as described in claim 63 further comprising computerized data handling componentry configured to handle data generated by said at least one measured, instantaneous intra-string current difference determinator.

75-123. -123. (canceled)