Method and apparatus for fault identification in a power tansmission line
View Patent ↗A method and apparatus for fault identification in a transmission line are provided. The method may include measuring at an end of the transmission line when the transmission line has a fault to obtain a measured signal, comparing the measured signal with a predefined standard signal, the predefined standard signal having beat frequency characteristic; and identifying that the fault is a transient fault if the measured signal matches the predefined standard signal according to a result of the comparison, or the fault is a permanent fault if the measured signal does not match the predefined standard signal according to the result of the comparison.
1. A method for fault identification in a transmission line, the method comprising:
in response to an occurrence of a fault on a transmission line, measuring at an end of the transmission line a signal over time to obtain a measured signal defining a waveform of zero and non-zero values;
comparing the measured signal with a predefined standard signal over a signal data window length of time to determine values of an amount of similarity between respective waveforms of the measure signal and the predefined standard signal over the signal data window length of time, wherein the signal data window length of time is selected to be longer than length of time of a beat frequency characteristic waveform of the predefined standard signal that has zero and non-zero values;
determining that the fault is a transient fault if the degree of similarity values exceed a threshold; and
determining that the fault is a permanent fault if the degree of similarity values do not exceed the threshold.
2. The method of claim 1 , wherein the degree of similarity between the measured signal and the predefined standard signal is a coefficient value K that is calculated by the following equation:
K
=
〈
g
(
t
)
,
f
(
t
)
〉
g
(
t
)
2
f
(
t
)
2
;
K
∈
[
-
1
,
1
]
wherein t is the signal data window length of time, g(t) is a value of the measured signal over the signal data window length of time, and f(t) is a value of the predefined standard signal over the signal data window length of time.
3. The method of claim 1 , wherein the measured signal is a voltage signal or a current signal measured at the end of the transmission line.
4. The method of claim 1 , wherein the predefined standard signal is selected randomly on a precondition that the predefined standard signal has the beat frequency characteristic over the signal data window length of time.
5. The method of claim 1 , wherein the fault is a single-phase fault.
6. The method of claim 1 , further comprising:
determining that the fault is the transient fault if maximum values of a waveform of the determined values of the amount of similarity between the measured signal and the predefined standard signal fluctuate over the signal data window length of time; and
determining that the fault is the permanent fault if the maximum values of the waveform of the determined values of the amount of similarity between the measured signal and the predefined standard signal do not fluctuate over the signal data window length of time.
7. The method of claim 1 , wherein the threshold is set to 1.
8. The method of claim 1 , wherein the threshold is set to 10.
9. The method of claim 1 , wherein the threshold is set to 0.1.
10. An apparatus for fault identification in a transmission line, the apparatus comprising:
a measurement unit configured to measure at an end of the transmission line, when the transmission line has a fault, to obtain a measured signal defining a waveform of zero and non-zero values;
a comparison unit configured to compare the measured signal with a predefined standard signal over a signal data window length of time to determine values of an amount of similarity between respective waveforms of the measured signal and the predefined standard signal over the signal data window length of time, wherein the signal data window length of time is selected to be longer than length of time of a beat frequency characteristic waveform of the predefined standard signal that has zero and non-zero values; and
an identification unit configured to identify that the fault is a transient fault if the degree of similarity values exceed a threshold, or that the fault is a permanent fault if the degree of similarity values do not exceed the threshold.
11. The apparatus of claim 10 , wherein the degree of similarity between the measured signal and the predefined standard signal is a coefficient value K that is calculated by the following equation:
K
=
〈
g
(
t
)
,
f
(
t
)
〉
g
(
t
)
2
f
(
t
)
2
;
K
∈
[
-
1
,
1
]
wherein t is the signal data window length of time, g(t) is a value of the measured signal over the signal data window length of time, and f(t) is a value of the predefined standard signal over the signal data window length of time.
12. The apparatus of claim 10 , further comprising a standard signal generator configured to generate the standard signal having the beat frequency characteristic randomly.
13. The apparatus of claim 10 , wherein the measured signal is a voltage signal or a current signal measured at the end of the transmission line.
14. The apparatus of claim 10 , wherein the threshold is set to 1.
15. The apparatus of claim 10 , wherein the threshold is set to 10.
16. The apparatus of claim 10 , wherein the threshold is set to 0.1.
17. The apparatus of claim 10 , wherein the fault is a single-phase fault.
18. The apparatus of claim 10 , wherein the fault is determined to be the transient fault if maximum values of a waveform of the determined values of the amount of similarity between the measured signal and the predefined standard signal fluctuate over the signal data window length of time, and as the permanent fault if the maximum values of the waveform of the determined values of the amount of similarity between the measured signal and the predefined standard signal do not fluctuate over the signal data window length of time.