PARTIAL DISCHARGE MONITORING METHOD AND SYSTEM

• US 20110248721A1
• Filed: 07/22/2009
• Published: 10/13/2011
• Est. Priority Date: 08/06/2008
• Status: Active Grant

• Current Assignee: Eskom Holdings Limited
• Original Assignee: Eskom Holdings Limited
• Inventors: Higgins, Simon
• Granted Patent: US 9,229,042 B2
• Time in Patent Office: Days
• US Class Current: 324/537
• CPC Class Codes: G01R 1/00 Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 constructional details particular to electromechanical arrangements for measuring the electric consumption G01R11/02
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083
• CPC Class Codes: H01B 1/00 Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 2221/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
• CPC Class Codes: H02B 1/00 Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements

Abstract

The invention relates to a method and system of monitoring partial discharges occurring in an electrical system, and to a method of measuring or analyzing partial discharges occurring in an electrical system. The method comprising receiving a signal or impulse, or information associated therewith, from the electrical system; breaking the received signal or impulse into predefined frequency components; and displaying a peak of the received signal or impulse on a scatter plot with other peaks associated with similar predefined frequency components.

Claims

1. A method of monitoring partial discharges occurring in an electrical system, the method comprising:

receiving a signal or impulse, or information associated therewith, from the electrical system;

breaking the received signal or impulse into predefined frequency components;

discriminating noise or duplicated signals from the received signal or impulse; and

displaying a peak of the received signal or impulse on a scatter plot with other peaks associated with similar predefined frequency components.

2. The method as claimed in claim 1, the method comprising generating a scratchpad to store a predefined number of normalised spectra for different signals or impulses together with peak values associated with the signals or impulses.

3. The method as claimed in claim 1, the method further comprising:

storing a plurality of fault spectra in a database;

monitoring the electrical system to receive signals or impulses occurring in the electrical system; and

comparing, once a signal or impulse is received, a frequency spectrum associated with the detected signal or impulse with the plurality of fault spectra stored in the scratchpad or the database at least to determine if the frequency spectrum of the detected signal or impulse substantially matches any of the stored plurality of fault spectra.

4. The method as claimed in claim 3, the method comprising grouping fault spectra that, within a predefined limit, have similar frequency content.

5. The method as claimed in claim 3, the method comprising raising a suitable flag if a frequency spectrum of the detected impulse substantially matches any of the existing fault spectra.

6. The method as claimed in claim 5, wherein raising the flag comprises generating a fault descriptor.

7. The method as claimed in claim 5, wherein the flag is a fault descriptor.

8. The method as claimed in claim 3, the method comprising, in addition to raising a flag, storing data or the frequency spectrum associated with the received signal or impulse in the database if the frequency spectrum of the detected impulse does not substantially match any of the existing fault spectra.

9. The method as claimed in claim 3, the method comprising generating scatter plots from a sub-set of the fault spectra of the received signal or impulse.

10. The method as claimed in claim 1, the method comprising performing signal processing on the received signal or impulse.

11. The method as claimed in claim 10, the method comprising:

generating a frequency spectrum of the received signal or impulse; and

breaking the generated frequency spectrum into predefined frequency components.

12. The method as claimed in claim 11, wherein comparing the frequency spectrum associated with the detected or received signal or impulse with the existing fault spectra stored in the database is done by way of a fault matching algorithm.

13. The method as claimed in claim 1, the method comprising:

validating the received signal or impulse;

determining the peak value of the received signal or impulse; and

normalizing the peak values of each of the predefined frequency components of the detected impulse to a maximum level.

14. A system for monitoring partial discharges occurring in an electrical system, the system comprising:

a database for storing a plurality of fault spectra;

a monitoring module for monitoring the electrical system to receive signals or impulses, or information associated therewith, occurring in the electrical system; and

a comparator operable, once a signal or impulse is received, to compare a frequency spectrum associated with the received signal or impulse with the existing fault spectra stored in the database at least to determine if the frequency spectrum of the received signal or impulse substantially matches any of the existing fault spectra.

15. The system as claimed in claim 14, the system being arranged to raise a flag if a frequency spectrum of the received signal or impulse substantially matches any of the existing fault spectra.

16. The system as claimed in claim 15, wherein the system is arranged to store data or the frequency spectrum associated with the received signal or impulse in the database.

17. The system as claimed in claim 14, wherein the system comprises a data generating module operable to generate data associated with the received signal or impulse.

18. The system as claimed in claim 17, wherein the data generating module is configured to generate scatter plots from a sub-set of the fault spectra of the received signal or impulse.

19. The system as claimed in claim 14, wherein the monitoring module is in communication with a plurality of sensors, the sensors being arranged to monitor each phases of the electrical or power system.

20. The system as claimed in claim 14, the system comprising a frequency spectrum generating module operable to generate a frequency spectrum of the signal or impulse received by the monitoring module.

21. The system as claimed in claim 14, wherein the comparator is arranged to apply a fault matching algorithm to compare the frequency spectrum associated with the received signal or impulse with the existing fault spectra stored in the database.

22. The system as claimed in claim 14, the system further comprising:

a validation module arranged to validate the received signal or impulse;

a peak detector to determine the peak value of the received signal or impulse; and

a normalizing module arranged to normalize the peak values of each of the predefined frequency components of the received signal or impulse to a maximum level.

23. A method of measuring or analyzing partial discharges occurring in an electrical system, the method including

storing a plurality of fault spectra in a database;

monitoring the system to detect impulses occurring therein; and

once an impulse is detected, comparing a frequency spectrum associated with the detected impulse with the plurality of fault spectra stored in the database to at least determine if the frequency spectrum of the detected impulse substantially matches any of the stored plurality of fault spectra.

24. (canceled)

25. (canceled)