System and method of locating ground fault in electrical power distribution system
View Patent ↗A method for locating a ground fault in an electrical power distribution system includes providing a plurality of current sensors at a plurality of locations in the electrical power distribution system. The method further includes detecting a ground fault in the electrical power distribution system. Current is monitored at a plurality of locations in the electrical power distribution system via the current sensors and a test signal is introduced into the electrical power distribution system via a test signal generating device. The plurality of locations are monitored to locate the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected.
1. A method for locating a ground fault in an electrical power distribution system comprising:
providing a plurality of current sensors at a plurality of locations in the electrical power distribution system;
detecting a ground fault in the electrical power distribution system;
monitoring current at the plurality of locations in the electrical power distribution system via the current sensors;
introducing a test signal into a zero-sequence network of the electrical power distribution system via a test signal generating device; wherein the test signal is a tone signal at a harmonic frequency of the frequency of current distributed by the system; and
monitoring the plurality of locations to locate the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected.
2. The method of claim 1 , wherein the test signal is a pulse signal generated at desired intervals.
3. The method of claim 2 , wherein the pulse signal is generated by closing a switch coupled across a portion of a grounding resistor.
4. The method of claim 1 , wherein the harmonic frequency is a non integer harmonic frequency.
5. The method of claim 1 , wherein the tone signal is at two harmonic frequencies of the frequency of current distributed by the system.
6. The method of claim 1 , wherein monitoring the plurality of locations includes detecting current signals and converting current signals to phasor values.
7. A system for locating a ground fault in an electrical power distribution system comprising:
plurality of current sensors adapted to monitor current at a plurality of locations in the distribution system;
a test signal generating device configured to introduce a test signal into a zero-sequence network of the distribution system; wherein the test signal is a tone signal at a harmonic frequency of the frequency of current distributed by the system; and
a processor configured to receive signals from the current sensors to identify a location of the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected.
8. The system of claim 7 , wherein the test signal generating device comprises a switch coupled across a portion of a neutral grounding resistor of a substation transformer.
9. The system of claim 7 , further comprising a control unit configured to receive a signal from the processor and initiate a protective action when a ground fault is detected in the system.
10. A method for locating a ground fault in an electrical power distribution system comprising:
providing a plurality of current sensors at a plurality of locations in the electrical power distribution system;
detecting a ground fault in the electrical power distribution system;
monitoring current at the plurality of locations in the electrical power distribution system via the current sensors;
introducing a test signal into the electrical power distribution system via a test signal generating device; and
monitoring the plurality of locations to locate the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected
wherein locating the ground fault includes identifying zero sequence current values in phase with voltage across a grounding resistor.
11. The method of claim 10 , wherein the test signal is a tone signal at a harmonic frequency of the frequency of current distributed by the system.
12. The method of claim 11 , wherein the harmonic frequency is a non integer harmonic frequency.
13. A method for locating a ground fault in an electrical power distribution system comprising:
providing a plurality of current sensors at a plurality of locations in the electrical power distribution system;
detecting a ground fault in the electrical power distribution system;
monitoring current at the plurality of locations in the electrical power distribution system via the current sensors;
introducing a test signal into the electrical power distribution system via a test signal generating device; and
monitoring the plurality of locations to locate the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected
wherein locating the ground fault includes identifying zero sequence current values out of phase with current through a grounding resistor.
14. The method of claim 13 , wherein the test signal is a tone signal at a harmonic frequency of the frequency of current distributed by the system.
15. The method of claim 14 , wherein the harmonic frequency is a non integer harmonic frequency.
16. A system for locating a ground fault in an electrical power distribution system comprising:
plurality of current sensors adapted to monitor current at a plurality of locations in the distribution system;
a test signal generating device configured to introduce a test signal into the distribution system; and
a processor configured to receive signals from the current sensors to identify a location of the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected;
wherein locating the ground fault includes identifying zero sequence current values in phase with voltage across a grounding resistor.
17. A system for locating a ground fault in an electrical power distribution system comprising:
plurality of current sensors adapted to monitor current at a plurality of locations in the distribution system;
a test signal generating device configured to introduce a test signal into the distribution system; and
a processor configured to receive signals from the current sensors to identify a location of the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected;
wherein locating the ground fault includes identifying zero sequence current values out of phase with current through a grounding resistor.