U.S. patent application number 15/727720 was filed with the patent office on 2018-02-01 for method and device to identify, record and store traveling wave heads in electric power systems.
This patent application is currently assigned to Reason Tecnologia SA. The applicant listed for this patent is Reason Tecnologia SA. Invention is credited to Carlos Alberto Dutra, Conrado Werner Seibel.
Application Number | 20180031626 15/727720 |
Document ID | / |
Family ID | 41559400 |
Filed Date | 2018-02-01 |
United States Patent
Application |
20180031626 |
Kind Code |
A1 |
Dutra; Carlos Alberto ; et
al. |
February 1, 2018 |
METHOD AND DEVICE TO IDENTIFY, RECORD AND STORE TRAVELING WAVE
HEADS IN ELECTRIC POWER SYSTEMS
Abstract
METHOD AND DEVICE TO IDENTIFY, RECORD AND STORE TRAVELING WAVE
HEADS IN ELECTRIC POWER SYSTEMS consisting in sending a trigger (5)
signal generated from the monitoring of the basic values of voltage
and current of the electrical signal (1) of the transmission system
in its fundamental frequency of operation (50/60 Hz), where the
generated trigger (5) signal is controlled by continuous monitoring
of the parameters derived from the basic values of current and
voltage and tested against thresholds previously set by a user.
Inventors: |
Dutra; Carlos Alberto;
(Florianopolis SC, BR) ; Seibel; Conrado Werner;
(Florianopolis SC, BR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Reason Tecnologia SA |
Florianopolis SC |
|
BR |
|
|
Assignee: |
Reason Tecnologia SA
Florianopolis SC
BR
|
Family ID: |
41559400 |
Appl. No.: |
15/727720 |
Filed: |
October 9, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13254438 |
Mar 20, 2012 |
9784783 |
|
|
PCT/BR2010/000010 |
Jan 12, 2010 |
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15727720 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01R 31/08 20130101;
G01R 31/086 20130101 |
International
Class: |
G01R 31/08 20060101
G01R031/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2009 |
BR |
0901107-2 |
Claims
1. A system for determining the location of a fault in an electric
power transmission network, comprising: fault locating equipment
configured to be coupled to an electrical line of the power
transmission network, the equipment including a processing circuit
configured to: extract frequency components of an electrical signal
passing through the electrical line and related to a traveling wave
caused by the fault, the electrical signal having a fundamental
frequency of 50 Hz or 60 Hz; isolate at least one of a voltage or a
current of the electrical signal corresponding to the fundamental
frequency by removing components of the electrical signal having a
frequency greater than the fundamental frequency; derive a
parameter in the fundamental frequency from the isolated at least
one of the voltage or the current of the electrical signal; compare
the parameter in the fundamental frequency to a threshold; identify
the traveling wave caused by the fault in response to the parameter
in the fundamental frequency exceeding the threshold; and store a
sample of the electrical signal corresponding to when the parameter
in the fundamental frequency exceeded the threshold to determine
the location of the fault in the electrical line of the power
transmission network.
2. The system of claim 1, wherein the processing circuit includes a
low-pass filter configured to isolate the at least one of the
voltage or the current of the electrical signal.
3. The system of claim 2, wherein the processing circuit includes
an analog-to-digital converter which performs sampling of the
isolated at least one of the voltage or current of the electrical
signal to digitize the isolated at least one of the voltage or
current of the electrical signal.
4. The system of claim 1, wherein the processing circuit is
configured to continuously monitor the parameter in the fundamental
frequency.
5. The system of claim 1, wherein the threshold is a previously set
user threshold.
6. The system of claim 1, wherein the parameter in the fundamental
frequency derived from the voltage of the electrical signal
includes at least one of a root mean square (RMS) value, an RMS
neutral value, an RMS value of a fundamental component, an RMS
value of a neutral fundamental component, a frequency, a positive
sequence, a negative sequence, an imbalance, or a total harmonic
distortion.
7. The system of claim 1, wherein the parameter in the fundamental
frequency derived from the current of the electrical signal
includes at least one of a root mean square (RMS) value, an RMS
neutral value, an RMS value of a fundamental component, an RMS
value of a neutral fundamental component, a positive sequence, a
negative sequence, an imbalance, or a total harmonic
distortion.
8. The system of claim 1, wherein the processing circuit is
configured to derive the parameter in the fundamental frequency
from a power of the electrical signal, wherein the parameter in the
fundamental frequency derived from the power includes at least one
of a combined apparent power, a fundamental apparent power, a
fundamental active power, or a fundamental reactive power.
9. The system of claim 1, wherein the processing circuit is
configured to use Boolean equations to control generation of the
trigger signal using monitoring of a plurality of thresholds.
10. The system of claim 1, wherein the processing circuit is
configured to extract the frequency components of the electrical
signal by receiving the electrical signal on a first signal path,
and the processing circuit is configured to store a sample of the
electrical signal based on receiving the electrical signal on a
second signal path separate from the first signal path.
11. A method for determining the location of a fault in an electric
power transmission network, comprising: extracting, by a processing
circuit of fault locating equipment coupled to an electrical line
of the power transmission network, frequency components of an
electrical signal passing through the electrical line and related
to a traveling wave caused by the fault, the electrical signal
having a fundamental frequency of 50 Hz or 60 Hz; isolating, by the
processing circuit, at least one of a voltage or a current of the
electrical signal corresponding to the fundamental frequency by
removing components of the electrical signal having a frequency
greater than the fundamental frequency; deriving, by the processing
circuit, a parameter in the fundamental frequency from the isolated
at least one of the voltage or the current of the electrical
signal; comparing, by the processing circuit, the parameter in the
fundamental frequency to a threshold; identifying, by the
processing circuit, the traveling wave caused by the fault in
response to the parameter in the fundamental frequency exceeding
the threshold; and storing, by the processing circuit, a sample of
the electrical signal corresponding to when the parameter in the
fundamental frequency exceeded the threshold to determine the
location of the fault in the electrical line of the power
transmission network.
12. The method of claim 11, wherein the at least one of the voltage
or the current of the electrical signal is isolated by a low-pass
filter.
13. The method of claim 12, further comprising using an
analog-to-digital converter to sample the isolated at least one of
the voltage or current of the electrical signal to digitize the
isolated at least one of the voltage or current of the electrical
signal.
14. The method of claim 11, further comprising continuously
monitoring the parameter in the fundamental frequency.
15. The method of claim 11, wherein the threshold is a previously
set user threshold.
16. The method of claim 11, wherein the parameter in the
fundamental frequency derived from the voltage of the electrical
signal includes at least one of a root mean square (RMS) value, an
RMS neutral value, an RMS value of a fundamental component, an RMS
value of a neutral fundamental component, a frequency, a positive
sequence, a negative sequence, an imbalance, or a total harmonic
distortion.
17. The method of claim 11, wherein the parameter in the
fundamental frequency derived from the current of the electrical
signal includes at least one of a root mean square (RMS) value, an
RMS neutral value, an RMS value of a fundamental component, an RMS
value of a neutral fundamental component, a positive sequence, a
negative sequence, an imbalance, or a total harmonic
distortion.
18. The method of claim 11, further comprising deriving the
parameter in the fundamental frequency from a power of the
electrical signal, wherein the parameter in the fundamental
frequency derived from the power includes at least one of a
combined apparent power, a fundamental apparent power, a
fundamental active power, or a fundamental reactive power.
19. The method of claim 11, further comprising using Boolean
equations to control generation of the trigger signal using
monitoring of a plurality of thresholds.
20. The method of claim 11, wherein extracting the frequency
components of the electrical signal is performed based on receiving
the electrical signal on a first signal path, and storing the
sample of the electrical signal is performed based on receiving the
electrical signal on a second signal path separate from the first
signal path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/254,438, titled "METHOD AND DEVICE TO
IDENTIFY, RECORD AND STORE TRAVELING WAVE HEADS IN ELECTRIC POWER
SYSTEMS," filed Sep. 1, 2011, which is a U.S. national stage of PCT
Application No. PCT/BR2010/000010, filed Jan. 12, 2010, which
claims the benefit of and priority to Brazil Application No. PI
0901107-2, filed Mar. 5, 2009, the disclosures of which are
incorporated herein by reference in their entireties for any and
all purposes.
BACKGROUND
[0002] This report discloses a device used on electric power
transmission networks to identify and determine the location of
faults.
[0003] A fault is a random and unpredictable event in electric
power systems generated by short-circuits, burned up fields,
lightnings, falling down of towers, breakage of insulators, cables
and others. These faults are considered transitory when the supply
of electric power is not interrupted. Occasionally, when
interruption is needed, it is performed by security instruments in
order to protect the stability of the system and the equipment in
the transmission/distribution of the electric power. The occurrence
of faults in electric power systems is totally undesirable and
their causes must be identified and properly eliminated as soon as
possible.
[0004] In order to determine the location of these faults, a method
based upon the traveling waves it is used. Traveling waves in power
transmission lines continually occur by any discontinuity of the
electrical signals in the power network. Therefore, the most common
causes are related to faults and switching operations in order to
operate the system.
[0005] The fault location through traveling waves is based on
theory that a fault in a line brings about a high frequency pulse
(head) of an electromagnetic traveling wave. The detection of this
pulse with an extremely accurate time stamp allows the calculation
of the distance of the point where the fault has occurred. Each
wave comprises a frequency spectrum, from a few kHz to several MHz,
and has a fast ascending slope and slower descending slope. Its
propagation speed is close to the speed of light in the vacuum and
it is attenuated by the means of propagation. The waves travel
through the electric power system network until it has its
amplitude decreased due to the loss of power, impedance and
deflections occurred in the network.
[0006] A device to determine the location of faults based upon
traveling waves methods must show, as its main features, the
determination of the location, the measuring and recording of the
correct wave head caused by a specific fault.
[0007] Presently the devices found in the market show a great
inconvenience which is low reliability on detecting the correct
wave head related to a fault. This low reliability is due to the
strategy used to set off the trigger of the wave head measuring
system. The strategy of current devices is based on the level
(magnitude) of the wave head itself upon arriving at the measuring
system. Nevertheless, this trigger solution related only to the
wave head itself has shown to be of low reliability. The adjustment
accuracy of such kind of trigger may be very hard to be obtained
because of the high number of wave heads continually generated and,
therefore, sometimes the wave head detected is not the correct wave
head related to the fault. This is especially true when transitory
faults, set off by burned up fields, lightnings, dirt on the
insulators, etc., do not start the protection system and
consequently the line is not permanently shut off.
SUMMARY
[0008] The object of the present invention consists in a system to
determine the location of faults through traveling waves assuring
greater reliability due to the greater certainty of detecting the
correct traveling wave responsible for the fault in the
transmission line.
[0009] The inventive step is based upon the principle that a fault
not only generates a wave head but it also generates changes in the
electrical parameters of the current and voltage analogical signals
in the fundamental frequency (50/60 Hz) of the operation system.
That is, the basic signals of current and voltage in 50/60 Hz
suffer disturbances that alter the balance parameters associated
with their magnitude and frequency. The inventive step consists in
generating a trigger which is not based upon the level of the wave
head, but upon the continuous monitoring of the fault itself
through measurement of the basic values of the voltage and current
electrical signals in its fundamental frequency of operation (50/60
Hz). The changing of these basic values is continually monitored
and tested against thresholds previously defined by the user,
generating a trigger whenever one of these thresholds is
exceeded.
[0010] The device proposed comprises a signal conditioning module,
a high speed data acquisition module and a trigger generating
module. One advantage of the device that identifies the traveling
wave head to determine the location of faults in electric power
systems hereby presented is the elimination of the low reliability
in identifying and detecting the traveling wave related to a fault.
Another advantage of the device to identify the traveling wave head
hereby presented is the possibility of using this device in methods
determining the location based upon a "single-end" feature, which
consists in recording the traveling wave at one end of the line; a
"double-end" feature, which consists in recording the traveling
wave at both ends of the same line; or a combination of both
features. Another advantage of the device to identify the traveling
wave head hereby presented is the separation of the wave head
recording process from the wave head detection process. The
recording is performed by the data acquisition module and the
detection is performed by the trigger generating module.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The description of the drawings hereinafter allows the
comprehension of the wave head detection and recording system,
object of the present report.
[0012] FIG. 1 is a block diagram that shows the interconnection of
modules comprising the system, showing the electrical signal(1) of
the transmission line, the signal conditioning module(2), the high
speed data acquisition module(3) and the trigger(5) generating
module(4).
[0013] FIG. 2 is a block diagram that shows the elements of the
trigger(5) generating module(4).
[0014] FIG. 3 is a table that shows an example of the parameters
and thresholds that can be monitored by the system.
DETAILED DESCRIPTION
[0015] According to the figures shown, the electrical signal(1) of
the transmission line goes through the signal conditioning
module(2), and then through the high speed data acquisition
module(3) and then to the trigger(5) generating module(4).
[0016] The function of the signal conditioning module(2) is to
filter the basic signal(1) in order to keep only the frequency
components related to a traveling wave spectrum.
[0017] High speed data acquisition module(3) is responsible for
sampling the electrical signal(1) related to the traveling wave in
order to effectively record such wave continually sampling the
electrical signal.
[0018] The function of the trigger(5) generating module(4) is to
generate a trigger(5) in order to control the acquisition module(3)
informing such acquisition module(3) that it has to store the
sampled signal(1) related to a traveling wave. The trigger(5)
generating module(4) comprises a low-pass filter(41) set to the
electric signal(1) in order to remove the high frequency
components, mainly the ones related to the basic frequency (50/60
Hz); a low speed analog-to-digital converter A/D(42) to perform the
sampling of the electric signal(1) to digitize the information; a
derived values calculation module(43); and a threshold module(44)
which performs the test of the previously set thresholds to
generate the trigger(5) signal.
[0019] The threshold module(44) uses Boolean equations with the
purpose of obtaining more flexibility to control the generation of
such trigger(5) signal. The exceeded threshold can be combined by
using the Boolean logic "(A .LAMBDA. B .LAMBDA. C .LAMBDA. . . . )
V (D .LAMBDA. E .LAMBDA. F .LAMBDA. . . . ) V . . . " where: "A, B,
C, . . . " represent the result of the monitoring of the
thresholds. "A" represents the Boolean operator "AND" and "V"
represents the Boolean operator "OR". The final result of the
Boolean expression performed at the threshold module(44) is used to
generate the trigger(5) signal which is sent to the traveling waves
acquisition module(3).
[0020] Control of the trigger(5) signal is performed by continuous
monitoring the parameters derived from the basic values of current
and voltage tested in relation to the threshold previously set by
the user.
[0021] FIG. 3 shows a table with examples of the parameters and
thresholds that can be monitored according to the user's choice,
generating a trigger(5) whenever one of these thresholds is
exceeded.
[0022] The parameters derived from the basic value of voltage,
which are monitored by the user, are: the RMS (Root Mean Square)
value, the RMS neutral value, the RMS value of the fundamental
component, the RMS value of the neutral fundamental component, the
frequency, the positive sequence, the negative sequence, the
imbalance and the total harmonic distortion.
[0023] The parameters derived from the basic value of current,
which are monitored by the user, are: the RMS value, the RMS
neutral value, the RMS value of the fundamental component, the RMS
value of the neutral fundamental component, the positive sequence,
the negative sequence, the imbalance and the total harmonic
distortion.
[0024] The parameters derived from the basic value of power, which
are monitored by the user, are: the combined apparent power, the
fundamental apparent power, the fundamental active power and the
fundamental reactive power.
[0025] In this example, the specific parameter aforementioned have
been used to characterize the effective industrial usage of the
present invention, although it is possible to group other
parameters derived from the basic electrical values of "current"
and "voltage".
* * * * *