Sensor, Method and System of Monitoring Transmission Lines

• US 20090284249A1
• Filed: 03/03/2009
• Published: 11/19/2009
• Est. Priority Date: 09/08/2006
• Status: Active Grant

• Current Assignee: Genscape, Inc. (Verisk Analytics Incorporated)
• Original Assignee: Promethean Devices, LLC
• Inventors: Tesche, Frederick M., Barlow, Charles V., Syracuse, Steven J., Clark, Roy, Halverson, Peter G.
• Granted Patent: US 8,280,652 B2
• Time in Patent Office: Days
• US Class Current: 324/126
• CPC Class Codes: G01R 15/142 Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26
• CPC Class Codes: G01R 15/18 using inductive devices, e.g. transformers
• CPC Class Codes: G01R 19/2513 Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging

Abstract

An apparatus, method, and system for measuring the magnetic field produced by phase conductors in multi-phase power lines. The magnetic field measurements are used to determine the current load on the conductors. The magnetic fields are sensed by coils placed sufficiently proximate the lines to measure the voltage induced in the coils by the field without touching the lines. The x and y components of the magnetic fields are used to calculate the conductor sag, and then the sag data, along with the field strength data, can be used to calculate the current load on the line and the phase of the current. The sag calculations of this invention are independent of line voltage and line current measurements. The system applies a computerized fitter routine to measured and sampled voltages on the coils to accurately determine the values of parameters associated with the overhead phase conductors.

Claims

1. A computerized system for determining the physical location of phase conductors in addition to the magnitude, phase, or frequency of the currents on the phase conductors, the system comprising:

an apparatus for measuring the three dimensional phase and magnitude of the magnetic field emanating from the phase conductors, said apparatus comprising at least one orthogonally-oriented pair of magnetic field sensors for positioning remotely from a phase conductor, said sensors comprising at least a pair of coaxial conductive windings having opposite polarity from a common center ground, said opposite polarity windings substantially canceling the electric field signal on said windings and generating an open circuit voltage between the respective ends of each winding;

a multi-channel analog to digital converter for sampling the induced open circuit voltage;

a data processing module implemented on a computer for processing the digital signals from the analog to digital converter, said digital signals representing the real time voltage signal outputs of said sensors, said data processing module comprising;

at least one digital band pass filter for isolating at least the fundamental frequency of each voltage signal;

a phase determination module for identifying the phase of each said voltage signal from each said sensor;

an amplitude determination module for identifying the amplitude of each said voltage signal from each of said sensors.

2. A computerized system according to claim 1, wherein said open circuit voltage is a differential input to a low pass filter.

3. A computerized system according to claim 1, further comprising a low pass filter connected to each of said at least one pair of magnetic field sensors for filtering the open circuit voltage signal generated by each of said windings.

4. A computerized system according to claim 3, wherein said low pass filter is an RC low pass filter.

5. A computerized system according to claim 4, wherein said RC low pass filter has a cut-off frequency of 98 Hz.

6. A computerized system according to claim 1, further comprising an oscillator for improving the accuracy of the analog to digital converter.

7. A computerized system according to claim 1, wherein said apparatus is positioned remotely from the phase conductors but within the measurable magnetic field emanating from said phase conductors.

8. A computerized system according to claim 1, wherein said analog to digital converter samples the voltage signals at 8000 samples per second for 4 seconds.

9. A computerized system according to claim 1, wherein the output of each said analog to digital converter is a 16 bit number representing voltages.

10. A computerized system according to claim 1, wherein said phase determination module and said amplitude determination module utilize a Blackman window.

11. A computerized system according to claim 1, wherein said amplitude determination module provides an output of the voltage signal magnitude in volts root mean square.

12. A computerized system according to claim 1, wherein said apparatus for measuring the magnetic field comprises at least three pairs of sensors providing six voltage signals.

13. A computerized system according to claim 1, wherein each sensor in a pair is positioned orthogonally to the other sensor in that pair for sensing only the X and Y components of the AC magnetic fields produced by a phase conductor.

14. A computerized system according to claim 1, wherein said analog to digital converter is an eight channel analog to digital converter, accepting voltage measurements from each sensor.

15. A computerized system according to claim 1, said system powered by a solar panel.

16. An apparatus for measuring the three dimensional phase and magnitude of the magnetic field emanating from overhead transmission and distribution phase conductors, comprising:

at least one magnetic field sensor for positioning remotely from the phase conductor, said sensor comprising at least a pair of parallel conductive windings having opposite polarity from a common ground, said opposite polarity windings substantially canceling the electric field signal on said windings and generating an open circuit voltage between the ungrounded ends of each winding.

17. An apparatus according to claim 16, wherein said windings comprise an enclosed area of at least 150 turn-meters squared.

18. An apparatus according to claim 16, further comprising a substantially cylindrical bobbin, wherein said windings are separately turned about respective side-by-side cross sectional thicknesses of said bobbin.

19. An apparatus according to claim 18, wherein said windings are of the same material, length, and turn-radius.

20. An apparatus according to claim 18, wherein said bobbin comprises a core selected from the group consisting of a hollow core, an air-filled core, a ferrite core, a core made of an alloy of nickel and iron, and a met-glass core.

21. An apparatus according to claim 16, comprising at least three pairs of said magnetic field sensors for positioning below an overhead power transmission line, wherein each pair of sensors is positioned under one phase conductor in a three-phase transmission system.

22. An apparatus according to claim 16, wherein said sensor is positioned sufficiently proximate to said phase conductor such that said open circuit voltage between windings is at least 100 millivolt AC.

23. An apparatus according to claim 22 wherein said open circuit voltage is between about 100 and about 400 millivolt AC.

24. An apparatus according to claim 16, comprising at least one pair of said magnetic field sensors, wherein said pair of sensors is positioned orthogonally without intersecting so as to sense only the X and Y components of the AC magnetic fields produced by the phase conductor.

25. An apparatus according to claim 16, wherein said open circuit AC voltage represents the X and Y components of the AC magnetic fields at least three distinct ground locations, produced by at least one three phase distribution circuit.

26. A computerized method of remotely measuring the physical height of three or more phase conductors in a power transmission and distribution system, in addition to the magnitude and phase of the current on the conductors, the method comprising:

positioning at least one orthogonally-oriented pair of electric field canceling magnetic field sensors such that the magnetic field of a phase conductor generates an open circuit voltage between the respective ends of each coil in the sensors;

measuring the open circuit voltages on each sensor by sampling the open circuit voltage with an analog to digital converter;

predicting the actual values for the height of the phase conductors and the magnitude and phase of the current on the phase conductors by using a computer processor to determine the actual values that would generate the measured voltages on the sensors.

27. A computerized method according to claim 26, wherein the height is measured from the sensor.

28. A computerized method according to claim 26, further comprising the step of calculating the sag of each conductor.

29. A computerized method according to claim 26, further comprising the step of calculating the clearance of each conductor.

30. A computerized method according to claim 26, further comprising the step of calculating the frequency of the current on the phase conductor.

31. A computerized method according to claim 26, further comprising the step of calculating the magnitude of the current on the phase conductor.

32. A computerized method according to claim 26, further comprising the step of calculating the phase of the current on the phase conductor.

33. A computerized method according to claim 26, further comprising the step of calculating the temperature of the phase conductor.