Methods and apparatus for analyzing partial discharge in electrical machinery

• US 20080088314A1
• Filed: 10/13/2006
• Published: 04/17/2008
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Salem, Sameh Ramadan, Younsi, Abdelkrim
• Granted Patent: US 7,579,843 B2
• Time in Patent Office: Days
• US Class Current: 324/457
• CPC Class Codes: G01R 31/1227 of components, parts or materials G01R31/1209, G01R31/1218, G01R31/18 take precedence; circuits therefor G01R31/14; testing vessels of electrodes G01R31/16

Abstract

Methods and apparatus for analyzing electrical insulation of an electrical machine are provided. The method includes receiving a first signal that includes a plurality of partial discharge pulses from the electrical machine and a plurality of noise pulses, receiving other signals that includes information relative to at least one process parameter associated with the electrical machine, determining the plurality of partial discharge pulses from the plurality of noise pulses, identifying characteristics of the plurality of partial discharge pulses relating to the location and character of partial discharges in the electrical machine, and determining a condition of the electrical insulation using the identified characteristics and the received information relative to at least one process parameter.

Claims

1. A method of analyzing electrical insulation of an electrical machine comprising:

receiving a first signal that includes a plurality of partial discharge pulses from the electrical machine and a plurality of noise pulses;

receiving a second signal that includes information relative to at least one process parameter associated with the electrical machine;

determining the plurality of partial discharge pulses from the plurality of noise pulses;

identifying characteristics of the plurality of partial discharge pulses relating to the location and character of partial discharges in the electrical machine; and

determining a condition of the electrical insulation using the identified characteristics and the received information relative to at least one process parameter.

2. A method in accordance with claim 1 wherein said receiving a signal that includes a plurality of partial discharge pulses from the electrical machine and a plurality of noise pulses comprises receiving at least one of a signal from a real-time sample from a partial discharge coupler connected to the electrical machine and a signal stored in a database.

3. A method in accordance with claim 1 wherein said receiving a second signal that includes information relative to at least one process parameter associated with the electrical machine comprises receiving a signal that includes information relative to at least one of voltage, current, real power, reactive power, temperature, vibration, a stator leak monitoring system (SLMS), flux probe signals, ozone levels, vibration, hydrocarbon concentration, protecting relaying device alarms, neutral current and voltage, field ground detector signal, hydrogen pressure, and combinations thereof.

4. A method in accordance with claim 1 further comprising generating a three dimensional histogram of the frequency of the magnitudes of phase resolved partial discharge pulses.

5. A method in accordance with claim 4 further comprising transforming the histogram to a time-length (T) versus bandwidth (W) map.

6. A method in accordance with claim 1 further comprising determining a cluster of points in a time-length (T) versus bandwidth (W) (WT) domain associated with the plurality of partial discharge pulses, each point representative of one of the plurality of partial discharge pulses or one of the plurality of noise pulses;

7. A method in accordance with claim 6 wherein determining a cluster of points in a time-length (T) versus bandwidth (W) (WT) domain comprises determining a cluster of points in the WT domain using at least one of a centroid, a standard deviation, a skewness, and a kurtosis of the cluster.

8. A method in accordance with claim 1 further comprising:

generating a phase resolved partial discharge pattern of the plurality of partial discharge pulses; and

identifying characteristics of the phase resolved partial discharge pattern that determines the shape of the plurality of partial discharge pulses.

9. A method in accordance with claim 8 further comprising:

grouping partial discharge pulses having similar characteristics; and

identifying a source of the grouped partial discharge pulses from characteristics of the grouped partial discharge pulses.

10. A method in accordance with claim 1 further comprising receiving at least one of the first and second signal in real time.

11. A method in accordance with claim 1 wherein the electrical machine is a process plant component, said method further comprising receiving the second signal from a plant-wide distributed control system.

12. A method in accordance with claim 1 further comprising;

storing at least one of the first and second signals in a database; and

associating the stored first signal with the stored second signal.

13. An apparatus for on-line location of partial discharge events in an AC power system during operation of the power system, said apparatus comprising:

a coupler adapted to couple to the AC power system and responsive to current flowing through the AC power system, coupler further adapted to detect high frequency electromagnetic pulses in the AC power system generated by partial discharge events; and

an analyzer system adapted to receive a first signal representative of the detected high frequency electromagnetic pulses and a second signal representative of a process parameter associated with at least one of the operation and environment of the AC power system during operation of the power system, said analyzer system further adapted to determine a location of partial discharge events in the power system using the first and second signals.

14. An apparatus in accordance with claim 13 wherein said analyzer system is adapted to be communicatively coupled to a data acquisition system adapted to acquire at least one input from a process parameter sensor and generate at least one said second signal.

15. An apparatus in accordance with claim 13 wherein said analyzer system is adapted to receive from a memory a first signal representative of high frequency electromagnetic pulses and a second signal representative of a process parameter associated with at least one of the operation and environment of the AC power system.

16. An apparatus in accordance with claim 13 wherein said analyzer system is adapted to time-stamp said received signals.

17. An apparatus in accordance with claim 13 wherein said analyzer system is adapted to:

determine time-based and frequency based characteristics of each pulse and a plurality of pulses in the first signal;

compare the determined characteristics to known characteristics of pulses and pluralities of pulses, the known characteristics being stored in a memory communicatively coupled to said analyzer system; and

determining a location and character of partial discharge events based on the comparison and the second signal.

18. An electrical machine monitoring system comprising:

a coupler adapted to couple to an AC power system and responsive to current flowing through the AC power system, said coupler further adapted to detect high frequency electromagnetic pulses in the AC power system generated by at least partial discharge events and to output a first signal representative of the high frequency electromagnetic pulses;

a data acquisition system adapted to acquire an input from at least one process parameter sensor associated with at least one of the operation and environment of the AC power system and to output a second signal representative of the at least one process parameter sensor; and

an analyzer system adapted to receive the first signal and the second signal, said analyzer system further adapted to determine a location of partial discharge events in the power system using the first and second signals.

19. An apparatus in accordance with claim 18 wherein said analyzer system is adapted to:

time-stamp the received first and second signals;

store the time-stamped first and second signals in a memory communicatively coupled to said analyzer system; and

receive from the memory the first signal and the second signal.

20. An apparatus in accordance with claim 18 wherein said analyzer system is adapted to:

determine time-based and frequency based characteristics of each pulse and a plurality of pulses in the first signal;

compare the determined characteristics to known characteristics of pulses and pluralities of pulses, the known characteristics being stored in a memory communicatively coupled to said analyzer system; and

determine a location and character of partial discharge events based on the comparison and the second signal.