Method and system for transformer dissolved gas harmonic regression analysis

• US 7,747,417 B2
• Filed: 08/06/2007
• Issued: 06/29/2010
• Est. Priority Date: 08/06/2007
• Status: Active Grant

• Current Assignee: Arizona Public Service Company (Pinnacle West Capital Corporation)
• Original Assignee: Arizona Public Service Company (Pinnacle West Capital Corporation)
• Inventors: Lamontagne, Donald R.
• Primary Examiner(s): Charioui; Mohamed
• Application Number:
  US11/834,500
• Publication Number:
  US 20090043538A1
• Time in Patent Office: 1,058 Days
• Field of Search: 702/25, 702/32, 702/34, 702/35, 702/50, 702/55, 702/56, 702/58, 702/66, 702/67, 702 69- 71, 702/79, 702/90, 702/104, 702/179, 702/182, 702/184, 702/185, 702/188, 702/189, 702/190, 700/292, 73/191.2, 73/530.1
• US Class Current: 702/188
• CPC Class Codes: H01F 2027/404 Protective devices specially adapted for fluid filled transformers
• CPC Class Codes: H01F 27/402 Association of measuring or protective means
• CPC Class Codes: H02H 5/08 responsive to abnormal fluid pressure, liquid level or liquid displacement, e.g. Buchholz relays

Abstract

A transformer (26) is monitored by a dissolved gas monitoring device (28). A method (36) in the form of executable code instructs a processor (34) to analyze a condition of the transformer (26). The method includes receiving (90), from the monitoring device (28), data elements (60) in the form of values (70) of dissolved gases (72) associated with operation of transformer (26) during a period of time. Periodic characteristics responsive to the operation of the transformer (26) are identified (92) from the data elements (60). The periodic characteristics may include a daily, semi-annual, and/or annual fluctuation of gas generation in response to transformer loading. A gas generation rate trend (112) is distinguished from the periodic characteristics, the condition of the transformer (26) is determined and its future condition may be predicted in response to the trend (112). The condition is presented to a user (58).

Claims

1. A method for analyzing a condition of electrical equipment monitored by a monitoring device comprising:

receiving data elements collected at said monitoring device that characterize behavior of said electrical equipment during operation of said electrical equipment over a period of time, said data elements being received at a processing system from said monitoring device;

identifying a periodic characteristic within said data elements responsive to said operation of said electrical equipment;

distinguishing a trend from said periodic characteristic, said data elements being transformed to said trend by canceling said periodic characteristic from said data elements to reveal said trend;

determining said condition of said electrical equipment in response to said trend; and

presenting said condition to a user.

2. A method as claimed in claim 1 wherein said periodic characteristic is a daily fluctuation in loading of said electrical equipment.

3. A method as claimed in claim 1 wherein said periodic characteristic is a semi-annual fluctuation in loading of said electrical equipment.

4. A method as claimed in claim 1 wherein said periodic characteristic is an annual fluctuation in loading of said electrical equipment.

5. A method as claimed in claim 1 wherein:

said identifying operation identifies multiple periodic characteristics, each of said multiple periodic characteristics describing a discrete periodic fluctuation in loading of said electrical equipment, said periodic characteristic being one of said multiple periodic characteristics; and

said distinguishing operation distinguishes said trend from each of said multiple periodic characteristics.

6. A method as claimed in claim 1 wherein said canceling operation reveals said trend as a substantially linear representation of said condition of said electrical equipment.

7. A method as claimed in claim 1 wherein said electrical equipment is a transformer maintained by a utility company, said monitoring device is a dissolved gas monitoring unit, said data elements are current values of a dissolved gas in transformer oil of said transformer, and said method further comprises performing said receiving, identifying, distinguishing, determining, and presenting operations at said processing system for said utility company.

8. A method as claimed in claim 1 wherein said electrical equipment is a transformer maintained by a utility company, said monitoring device is a dissolved gas monitoring unit, said data elements are current values of a dissolved gas in a volume of transformer oil in said transformer, and said determining operation determines a gas generation rate from said trend, said gas generation rate identifying said condition of said transformer.

9. A method as claimed in claim 1 further comprising predicting from said trend a future condition of said electrical equipment at a future time that follows said period of time.

10. A method as claimed in claim 1 wherein said period of time is a first period of time, said trend is a first trend, and said method further comprises:

receiving second data elements over a second period of time at said processing system from said monitoring device;

distinguishing a second trend from said periodic characteristic, said second trend differing from said first trend;

determining a change in said condition of said electrical equipment from said second trend; and

presenting said change in said condition to said user.

11. A method as claimed in claim 1 wherein:

said determining operation includes ascertaining from said trend that said condition defines an exception to a normal condition of said electrical equipment; and

said presenting operation includes conveying a notice of said condition to said user at an instance of said exception.

12. A computer-readable storage medium containing executable code for instructing a processor to analyze a condition of a transformer maintained by an organization and monitored by a dissolved gas monitoring device, said executable code instructing said processor to perform operations comprising:

receiving, from said monitoring device, data elements associated with operation of said transformer during a period of time, said data elements including current values of a dissolved gas in a volume of transformer oil in said transformer;

identifying, from said data elements, a periodic characteristic responsive to said operation of said transformer;

distinguishing a trend from said periodic characteristic by canceling said periodic characteristic from said data elements over said period of time to reveal said trend;

determining a gas generation rate of said dissolved gas from said trend, said gas generation rate identifying a condition of said transformer; and

presenting said condition to a user.

13. A computer-readable storage medium as claimed in claim 12 wherein said executable code instructs said processor to perform further operations comprising:

identifying multiple periodic characteristics, each of said multiple periodic characteristics describing a discrete periodic fluctuation in loading of said transformer, said periodic characteristic being one of said multiple periodic characteristics; and

said distinguishing operation distinguishes said trend from each of said multiple periodic characteristics.

14. A computer-readable storage medium as claimed in claim 13 wherein said multiple periodic characteristics include a daily fluctuation, a semi-annual fluctuation, and an annual fluctuation.

15. A computer-readable storage medium as claimed in claim 12 wherein said executable code instructs said processor to perform a further operation comprising predicting from said trend a future condition of said transformer at a future time that follows said period of time.

16. A computer-readable storage medium as claimed in claim 12 wherein said executable code instructs said processor to perform further operations comprising:

ascertaining from said trend that said condition defines an exception to a normal condition of said transformer; and

conveying a notice of said condition to said user at an instance of said exception.

17. A computing system for analyzing a condition of electrical equipment monitored by a monitoring device comprising:

a processor;

an input element, in communication with said processor, for receiving data elements from said monitoring device, said data elements being associated with operation of said electrical equipment during a period of time;

a computer-readable storage medium; and

executable code recorded on said computer-readable storage medium for instructing said processor to perform operations comprising;

identifying, from said data elements, multiple periodic characteristics responsive to said operation of said electrical equipment, each of said multiple periodic characteristics describing a discrete periodic fluctuation in loading of said electrical equipment;

distinguishing a trend from said periodic characteristics by canceling said multiple periodic characteristics from said data elements over said period of time to reveal said trend; and

determining said condition of said electrical equipment in response to said trend; and

an output element in communication with said processor for presenting said condition to a user.

18. A computing system as claimed in claim 17 wherein said executable code instructs said processor to perform a further operation comprising predicting from said trend a future condition of said electrical equipment at a future time that follows said period of time.

19. A computing system as claimed in claim 17 wherein said period of time is a first period of time, said trend is a first trend, and said executable code instructs said processor to perform further operations comprising:

receiving second data elements over a second period of time from said monitoring device;

distinguishing a second trend from said multiple periodic characteristics, said second trend differing from said first trend;

determining a change in said condition of said electrical equipment from said second trend; and

presenting said change in said condition to said user.