Cable fault detection
View Patent ↗A cable fault detection component ( 168 ) receives input data indicative of a fault in an electrical power system. The component ( 168 ) analyzes the input data to determine if the fault is indicative of a temporary or self-clearing cable fault and generates corresponding output data ( 276 ). In one implementation, the cable fault detection component ( 168 ) is implemented as a software module which operates on a computer ( 105 ) of a substation intelligence system ( 104 ).
1. A method of analyzing an anomaly in a cable carrying AC power, the method comprising:
detecting an anomaly with regard to the AC power in the cable;
upon detecting the anomaly, recording data concerning characteristics of the AC power for a predetermined period of time, the data comprising oscillographic data indicative of a time varying signal of cable current;
transmitting the data to an analysis location; and
at the analysis location, analyzing the data to determine whether the anomaly is a cable fault, the analyzing comprising:
performing a Fourier transform of the data; and
using the Fourier transformed data to determine whether the anomaly is a cable fault; and
wherein the Fourier transformed data comprises domain data indicative of a frequency component of the cable current, wherein the frequency domain data includes a peak at the AC power frequency and wherein a magnitude of the peak is indicative of the fundamental cable current.
2. The method of claim 1 , wherein the anomaly is an overcurrent burst.
3. The method of claim 2 , wherein the predetermined period of time is greater than one cycle of the AC power frequency.
4. The method of claim 1 , further comprising receiving a value for the predetermined period of time from a user through a human machine interface.
5. The method of claim 1 , wherein the step of detecting the anomaly is performed at a location remote from the analysis location.
6. The method of claim 1 , wherein the step of detecting the anomaly is performed by a protective relay.
7. The method of claim 6 , wherein the anomaly is an overcurrent burst and the step of detecting the anomaly is performed by an overcurrent protection element of the protective relay.
8. The method of claim 7 , wherein the overcurrent protection element is an instantaneous ground time overcurrent protection element.
9. The method of claim 6 , wherein the anomaly is a voltage deviation.
10. A method of analyzing an anomaly in a cable carrying AC power, the method comprising:
detecting an anomaly with regard to the AC power in the cable;
upon detecting the anomaly, recording data concerning characteristics of the AC power for a predetermined period of time;
transmitting the data to an analysis location; and
at the analysis location, analyzing the data to determine whether the anomaly is a cable fault, the analyzing comprising:
performing a Fourier transform of the data, the Fourier transformed data comprising data representative of cable current; and
using the Fourier transformed data to determine whether the anomaly is a cable fault, comprising:
determining whether the cable current exceeds a predetermined threshold value so as to comprise an overcurrent event; and
if the cable current exceeds the predetermined threshold value, determining whether a duration of the overcurrent event is less than a threshold fault duration.
11. The method of claim 10 , wherein the step of using the Fourier transformed data further comprises determining whether the overcurrent event began at or near a voltage peak.
12. The method of claim 11 , wherein the anomaly is determined to be a cable fault if predetermined criteria is met, the predetermined criteria comprising: the cable current exceeding the predetermined threshold value so as to comprise an overcurrent event, the overcurrent event beginning at or near a voltage peak, and the overcurrent event having a duration that is less than the threshold fault duration.
13. The method of claim 12 , wherein the predetermined criteria further comprises the detection of precipitation.
14. The method of claim 10 , wherein the step of detecting the anomaly is performed by a protective relay.
15. The method of claim 14 , wherein the protective relay comprises a plurality of overcurrent protection elements that are selectable by a user through a human machine interface to perform the detection of the anomaly, and wherein the method further comprises receiving a selection of a first one of the overcurrent protection elements to perform the detection of the anomaly.
16. The method of claim 15 , wherein the first one of the overcurrent protection elements is an instantaneous ground time overcurrent protection element.
17. The method of claim 14 , wherein the anomaly is a trip of an overcurrent protection element of the protective relay.