ANALYZING PARTIAL DISCHARGE IN AN ELECTRIC POWER DISTRIBUTION SYSTEM

• US 20150160284A1
• Filed: 12/11/2014
• Published: 06/11/2015
• Est. Priority Date: 12/11/2013
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: CERN, Yehuda
• Granted Patent: US 10,073,132 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/12 Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing G01R31/08, G01R31/327 and G01R31/72 take precedence; measuring in plasmas G01R19/0061; measuring dielectric constants G01R27/2617; ESD, EMC or EMP testing of circuits G01R31/002
• CPC Class Codes: G01R 31/1272 of cable, line or wire insulation, e.g. using partial discharge measurements locating faults in cables G01R31/083

Abstract

There is provided a method that includes (a) detecting a partial discharge on a power line that carries a power signal, (b) measuring a characteristic of the partial discharge, thus yielding a measured characteristic, (c) determining that the measured characteristic satisfies a measurement criterion, thus yielding a qualified partial discharge, (d) incrementing a count of cycles of the power signal that contain qualified partial discharges, (e) calculating, for a plurality of cycles of the power signal, based on the count, a percentage of the plurality of cycles that contain qualified partial discharges, and (f) utilizing the percentage in a subsequent operation. There is also provided a system that performs the method, and a storage device that contains instructions for a processor to perform the method.

Claims

1. A method comprising:

detecting a partial discharge on a power line that carries a power signal;

measuring a characteristic of said partial discharge, thus yielding a measured characteristic;

determining that said measured characteristic satisfies a measurement criterion, thus yielding a qualified partial discharge;

incrementing a count of cycles of said power signal that contain qualified partial discharges;

calculating, for a plurality of cycles of said power signal, based on said count, a percentage of said plurality of cycles that contain qualified partial discharges; and

utilizing said percentage in a subsequent operation.

2. The method of claim 1, wherein said subsequent operation comprises:

determining that said percentage satisfies a percentage criterion; and

issuing an alert.

3. The method of claim 1,

wherein said characteristic comprises a magnitude of said partial discharge, and

wherein said measurement criterion comprises a magnitude criterion.

4. The method of claim 3, wherein said characteristic comprises a phase of a cycle of said power signal at which said partial discharge occurred.

5. The method of claim 3, wherein said partial discharge is a partial discharge having a greatest magnitude in a cycle of said power signal.

6. The method of claim 3,

wherein said plurality of cycles is a first plurality of cycles having a first plurality of qualified partial discharges, and

wherein said method further comprises:

calculating a first representative magnitude for said first plurality of qualified partial discharges;

repeating, after a passage of time, said detecting, said measuring, said determining, said incrementing, and said calculating, for a second plurality of cycles of said power signal having a second plurality of qualified partial discharges; and

calculating a second representative magnitude for said second plurality of qualified partial discharges,

wherein said subsequent operation comprises;

calculating an amount of change from said first representative magnitude to said second representative magnitude;

determining that said amount of change exceeds an amount of change criterion; and

issuing an alert.

7. The method of claim 1,

wherein said plurality of cycles is a first plurality of cycles, and said percentage is a first percentage, and

wherein said method further comprises:

repeating, after a passage of time, said detecting, said measuring, said determining, said incrementing, and said calculating, for a second plurality of cycles of said power signal, to yield a second percentage,

wherein said subsequent operation comprises;

calculating a percentage change from said first percentage to said second percentage;

determining that said percentage change exceeds a percentage change criterion; and

issuing an alert.

8. The method of claim 1, further comprising:

receiving an indication of an occurrence of a fault of said power line;

analyzing measured characteristics for a plurality of qualified partial discharges, thus yielding analyzed data; and

determining from said analyzed data, a correlation between said qualified partial discharges and said fault, thus yielding a predictor of said fault.

9. The method of claim 8,

wherein said power line is a first power line, and

wherein said method further comprises:

utilizing said predictor in an analysis of partial discharges from a second power line; and

characterizing a condition of said second power line, based on said analysis of partial discharges from said second power line.

10. The method of claim 1, further comprising:

sensing peak power current flowing through said power line during said plurality of cycles, thus yielding peak power current data;

receiving an indication of an occurrence of a fault of said power line;

analyzing (a) measured characteristics for a plurality of qualified partial discharges, and (b) said peak power current data, thus yielding analyzed data; and

determining from said analyzed data, a correlation between said qualified partial discharges, said peak power current, and said fault, thus yielding a predictor of said fault.

11. A system comprising:

a processor; and

a memory that contains instructions that are readable by said processor to cause said processor to perform the method of claim 1.

12. A storage device comprising instructions that are readable by a processor to cause said processor to perform the method of claim 1.

13. A system comprising:

an inductive coupler that couples a partial discharge from a power line that carries a power signal;

a detector, downstream of said inductive coupler, that detects said partial discharge;

a processor, downstream of said inductive coupler; and

a memory that contains instructions that are readable by said processor to cause said processor to perform operations of;

measuring a characteristic of said partial discharge, thus yielding a measured characteristic;

determining that said measured characteristic satisfies a measurement criterion, thus yielding a qualified partial discharge;

incrementing a count of cycles of said power signal that contain qualified partial discharges;

calculating, for a plurality of cycles of said power signal, based on said count, a percentage of said plurality of cycles that contain qualified partial discharges; and

utilizing said percentage in a subsequent operation.

14. The system of claim 13, wherein said subsequent operation comprises:

determining that said percentage satisfies a percentage criterion; and

issuing an alert.

15. The system of claim 13,

wherein said characteristic comprises a magnitude of said partial discharge, and

wherein said measurement criterion comprises a magnitude criterion.

16. The system of claim 13,

wherein said plurality of cycles is a first plurality of cycles, and said percentage is a first percentage, and

wherein said instructions also cause said processor to perform operations of:

repeating, after a passage of time, said detecting, said measuring, said determining, said incrementing, and said calculating, for a second plurality of cycles of said power signal, to yield a second percentage,

wherein said subsequent operation comprises;

calculating a percentage change from said first percentage to said second percentage;

determining that said percentage change exceeds a percentage change criterion; and

issuing an alert.

17. The system of claim 13, wherein said instructions also cause said processor to perform operations of:

receiving an indication of an occurrence of a fault of said power line;

analyzing measured characteristics for a plurality of qualified partial discharges, thus yielding analyzed data; and

determining from said analyzed data, a correlation between said qualified partial discharges and said fault, thus yielding a predictor of said fault.

18. The system of claim 13, wherein said instructions also cause said processor to perform operations of:

sensing peak power current flowing through said power line during said plurality of cycles, thus yielding peak power current data;

receiving an indication of an occurrence of a fault of said power line;

analyzing (a) measured characteristics for a plurality of qualified partial discharges, and (b) said peak power current data, thus yielding analyzed data; and

determining from said analyzed data, a correlation between said qualified partial discharges, said peak power current, and said fault, thus yielding a predictor of said fault.