Automated system approach to analyzing harmonic distortion in an electric power system

• US 20070179726A1
• Filed: 03/23/2007
• Published: 08/02/2007
• Est. Priority Date: 07/01/2005
• Status: Active Grant

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Bickel, Jon
• Granted Patent: US 7,469,190 B2
• Time in Patent Office: Days
• US Class Current: 702/69
• CPC Class Codes: G01D 4/002 Remote reading of utility meters
• CPC Class Codes: G01R 22/063 related to remote communication
• CPC Class Codes: H02J 3/01 Arrangements for reducing harmonics or ripples
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y02E 40/40 Arrangements for reducing harmonics
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A method and system to detect and evaluate harmonic distortion in an electrical power system is disclosed. A plurality of monitoring devices is installed in the electrical power system. The hierarchy of the electrical power system is received. Data indicative of harmonic distortion on the electrical power system is received from at least two of said plurality of monitoring devices. The data indicative of harmonic distortion is automatically aligned in a temporal or pseudo-temporal context. An electrical characteristic of the harmonic distortion from the data indicative of harmonic distortion is determined.

Claims

1. A method of harmonic distortion monitoring in an electrical power system, comprising:

installing a plurality of monitoring devices in the electrical power system;

receiving the hierarchy of the electrical power system;

receiving data indicative of harmonic distortion on the electrical power system from at least two of said plurality of monitoring devices;

automatically aligning the data indicative of harmonic distortion in a temporal or pseudo-temporal context; and

determining an electrical characteristic of the harmonic distortion from the data indicative of harmonic distortion.

2. A computer readable medium encoded with instructions for directing a controller to perform the method of claim 1.

3. The method of claim 1, wherein the electrical characteristics of the harmonic distortion include at least one of the group consisting of 1) total voltage harmonic distortion;

2) total current harmonic distortion;

     3) discrete harmonic distortion component magnitudes and angles (voltages, currents, and powers);

     4) discrete harmonic distortion component flow directions;

     5) discrete interharmonic distortion component magnitudes (voltages, currents, and powers);

     6) discrete interharmonic distortion component flow directions;

     7) affected phase(s) (A,B,C);

     8) total even harmonic distortion and total odd harmonic distortion;

     9) triplens;

     10) harmonic distortion associated with three-phase rectifiers;

     11) harmonic distortion associated with positive sequence components;

     12) harmonic distortion associated with negative sequence components;

     13) harmonic distortion associated with zero-sequence components;

     14) true power factor versus displacement power factor;

     15) crest factors;

     16) total demand distortion; and

     17) neutral current flows.

4. The method of claim 1, further comprising comparing the data indicative of harmonic distortion with a threshold value to determine whether the data indicative of a harmonic distortion represents a harmonic distortion signal.

5. A method of claim 1, further comprising determining potential sources for harmonic distortion in the electrical power system based on the detected harmonic distortion characteristic.

6. The method of claim 1, further comprising classifying the potential harmonic distortion sources based on the harmonic distortion characteristics.

7. The method of claim 1, further comprising analyzing the harmonic distortion characteristics to determine a location of a harmonic distortion source or a harmonic distortion sink.

8. The method of claim 1, further comprising analyzing the harmonic distortion characteristics to determine an optimal location for a harmonic distortion mitigation device in the electrical power system.

9. The method of claim 10, further comprising determining the effects of mitigation devices on harmonic distortion in the electrical power system.

10. The method of claim 1, wherein the monitoring devices include a top level monitoring device on a circuit of the electrical power system and at least one lower level monitoring device on a subcircuit directly linked to the circuit, wherein the data indicative of harmonic distortion is sensed from at least one virtual monitoring point derived from the data sensed from the top level monitoring device and the at least one lower level monitoring device.

11. A system to monitor harmonic distortion in an electrical power system, comprising:

a plurality of monitoring devices in the electrical power system;

a central controller coupled to the plurality of monitoring devices, the central controller;

receiving data indicative of harmonic distortion on the electrical power system for at least some of the plurality of monitoring devices; and

automatically aligning the data indicative of harmonic distortion in a temporally or pseudo-temporally; and

determining an electrical characteristic of the harmonic distortion from the data indicative of harmonic distortion.

12. The system of claim 11, wherein the harmonic distortion characteristics include at least one of the group consisting of:

1) total voltage harmonic distortion;

     2) total current harmonic distortion;

     3) discrete harmonic distortion component magnitudes and angles (voltages, currents, and powers);

     4) discrete harmonic distortion component flow directions;

     5) discrete interharmonic distortion component magnitudes (voltages, currents, and powers);

     6) discrete interharmonic distortion component flow directions;

     7) affected phase(s) (A,B,C);

     8) total even harmonic distortion and total odd harmonic distortion;

     9) triplens;

     10) harmonic distortion associated with three-phase rectifiers;

     11) harmonic distortion associated with positive sequence components;

     12) harmonic distortion associated with negative sequence components;

     13) harmonic distortion associated with zero-sequence components;

     14) true power factor versus displacement power factor;

     15) crest factors;

     16) total demand distortion; and

     17) neutral current flows.

13. The system of claim 11, wherein the controller determines potential sources for harmonic distortion in the electrical power system based on the detected harmonic distortion characteristics.

14. The system of claim 11, wherein the controller classifies the harmonic distortion sources based on the harmonic distortion characteristics.

15. The system of claim 11, wherein the controller analyzes the harmonic distortion characteristics to determine a location of a harmonic distortion source or a harmonic distortion sink.

16. The system of claim 11, further comprising a mitigation evaluation module analyzing the harmonic distortion characteristics to determine an optimal location for a harmonic distortion mitigation device in the electrical power system.

17. The system of claim 11, wherein the monitoring devices include a top level monitoring device on a circuit of the electrical power system and at least one lower level monitoring device on a subcircuit directly linked to the circuit, wherein the controller determines data indicative of harmonic distortion via at least one virtual monitoring point derived from the data sensed from the top level monitoring device and the at least one lower level monitoring device.

18. A method of determining harmonic distortion on an electrical power system including a plurality of monitoring devices, the method comprising:

receiving the hierarchy of the electrical power system;

receiving data indicative of harmonic distortion on the electrical power system from at least two of said plurality of monitoring devices;

automatically aligning the data indicative of harmonic distortion temporally or pseudo-temporally;

analyzing the data indicative of harmonic distortion and comparing the analyzed data to a threshold value to confirm the presence of a harmonic distortion signal.

19. The method of claim 18, wherein the analyzing is performed via Fourier analysis.

20. The method of claim 18, further comprising determining the location of the source of the harmonic distortion signal in the electrical power system based on the data indicative of harmonic distortion.