KR101726938B1 - Current transformer saturation detection apparatus and medium of recording computer program for implementing current transformer saturation detection method - Google Patents

Current transformer saturation detection apparatus and medium of recording computer program for implementing current transformer saturation detection method Download PDF

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KR101726938B1
KR101726938B1 KR1020150045131A KR20150045131A KR101726938B1 KR 101726938 B1 KR101726938 B1 KR 101726938B1 KR 1020150045131 A KR1020150045131 A KR 1020150045131A KR 20150045131 A KR20150045131 A KR 20150045131A KR 101726938 B1 KR101726938 B1 KR 101726938B1
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pass filter
output signal
saturation
current transformer
filter
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KR1020150045131A
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Korean (ko)
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KR20160116832A (en
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강상희
김민수
박민우
정종진
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명지대학교 산학협력단
와이피피 주식회사
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    • G01R31/027—
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16—Spectrum analysis; Fourier analysis
    • G01R23/165—Spectrum analysis; Fourier analysis using filters

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Mathematical Physics (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

A method of detecting a current transformer saturation and an apparatus therefor are disclosed. A current transformer saturation detection device includes a multilevel filter bank and includes a wavelet transformer for filtering a current transformer secondary signal through the multistage filter bank and outputting the filtered signal as an output signal; A second high-pass filter for filtering and outputting a signal output from the wavelet transform unit; And a detector that detects a current transformer saturation using a peak of the filtered output signal.

Description

TECHNICAL FIELD [0001] The present invention relates to a current transformer saturation detection apparatus and a current transformer saturation detection method, and more particularly to a current transformer saturation detection apparatus and a medium recording computer program,

The present invention relates to a method and apparatus for detecting a current transformer saturation using wavelet transform.

The measurement of the current in the power system is usually done through a current transformer using an iron core. Since the iron core needs an exciting current to induce the magnetic flux, the secondary current always contains a certain amount of error. When the iron core flux exceeds the saturation point, the excitation current phenomenon occurs in which the excitation current abruptly increases.

When the current transformer saturates, the bias error increases, causing errors in various measuring instruments for measuring the current. Also, if the current transformer is saturated, it may cause malfunction or delay in operation time of the protection relay.

As a result, much research has been carried out for the detection of the current surge in the prior art. Conventional current transformer saturation detection is mainly performed by using a modal transform to detect current transformer saturation. In order to detect the current saturation using the conventional modal conversion, a precondition is required that all the phase currents must have only one frequency component. However, the phase current generally has only one frequency component.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for detecting a current saturation of a current transformer that can accurately detect a current transformer saturation region using wavelet transform.

It is still another object of the present invention to provide a method and apparatus for detecting a converter saturation using a second-order high-pass filter to clarify a signal of a wavelet transform result so as to more accurately and easily detect a current detector saturation.

It is another object of the present invention to provide a transformer saturation detection method and apparatus capable of eliminating errors in detection of a current transformer saturation caused by a switch phenomenon such as a reclosing phenomenon at a preceding stage using a secondary low-pass filter.

According to an aspect of the present invention, there is provided a current transformer saturation detection apparatus capable of accurately detecting a current transformer saturation period by discrete wavelet transform of a current transformer secondary signal.

According to an embodiment of the present invention, a wavelet transformer includes a multistage filter bank and filters a current transformer secondary signal through the multistage filter bank and outputs the filtered signal as an output signal. A second high-pass filter for filtering and outputting a signal output from the wavelet transform unit; And a detector for detecting a current transformer saturation using a peak of the filtered output signal.

The wavelet transform unit may be a two-stage filter bank, and each of the stage filter banks may include a low-pass filter and a high-pass filter.

The wavelet transform unit may continuously decompose the approximate information of the transformer secondary signal through the two-stage filter bank and output the output signal.

Wherein the wavelet transformer passes the transformer secondary signal through a low-pass filter and a high-pass filter of a first-stage filter bank and transmits a signal that has passed through a low-pass filter of the first-stage filter bank to a low- Pass filter and a high-pass filter, wherein the output signal is a transformer secondary signal that has passed through the high-pass filter of the second-stage filter bank.

The detection unit determines that a point at which a (2n-1) th peak of a threshold value or more occurs after the occurrence of a fault in the filtered output signal as a starting point of the current transformer saturation, and a point at which a 2nth peak occurs is referred to as a current transformer saturation end point Where n is a natural number.

And a second low-pass filter coupled to a downstream end of the second high-pass filter for filtering an output signal having passed through the second high-pass filter and filtering the designated high-frequency band.

Wherein the detection unit sets a first threshold value by multiplying a reference fault current by a filter gain and determines a time when the output signal exceeds the first threshold to be a failure moment, Pass through the wavelet transform unit, the second high-pass filter, and the second low-pass filter.

Wherein the detecting unit sets the peak value of the output signal generated at the moment of the failure to a second threshold value for detecting the saturation start point and sets a half value of the peak of the output signal generated at the saturation start point to the saturation end point Detecting a time point at which the magnitude of the output signal is equal to or greater than the second threshold value as the saturation start point and setting a time point at which the magnitude of the output signal is equal to or greater than the third threshold value, Time point.

The detector may detect a positive or negative peak value of the output signal in accordance with the phase angle of the voltage at the time of failure to detect a current saturated section.

According to another aspect of the present invention, there is provided a computer-readable recording medium product recorded with a program code for performing a transformer saturation detection method capable of accurately detecting a current transformer saturation interval by discrete wavelet transform of a current signal of a current transformer secondary signal .

According to an embodiment of the present invention, there is provided a method of converting a current transformer secondary signal into an output signal by filtering the transformer secondary signal through a multi-stage filter bank; Filtering and outputting the output signal; And detecting a current transformer saturation by using a peak of the filtered output signal. A computer readable recording medium product recording the program code may be provided.

By providing a method and an apparatus for detecting a current transformer saturation according to an embodiment of the present invention, accurate converter saturation can be detected using wavelet transform.

Further, the present invention makes it possible to make the detection of the current transformer saturation more accurate and easier by making the signal of the wavelet transform result clear by using the second-order high-pass filter.

Further, the present invention can eliminate the error of the current detector saturation detection caused by the switch phenomenon such as the reclosing phenomenon of the preceding stage by using the second-order low-pass filter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram schematically showing a configuration of a current detector saturation detecting apparatus according to an embodiment of the present invention; FIG.
2 illustrates a detailed configuration of a signal conversion unit according to an embodiment of the present invention;
FIGS. 3 to 6 are graphs showing a transformer primary / secondary signal and signal conversion results according to an embodiment of the present invention; FIG.
7 is a flowchart showing a method of detecting a current transformer saturation according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing a configuration of a current detector saturation detecting apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing a detailed configuration of a signal converting unit according to an embodiment of the present invention, 6 is a graph showing a transformer primary / secondary signal and signal conversion results according to an embodiment of the present invention.

Referring to FIG. 1, a current transformer saturation detecting apparatus 100 according to an embodiment of the present invention includes a signal converting unit 110 and a detecting unit 120.

The signal converter 110 includes a multistage filter bank, receives the secondary signal of the current transformer, performs discrete wavelet transform on the secondary signal of the current transformer through the multistage filter bank, and outputs the result as an output signal to the detector 120 .

2 shows a detailed structure of the signal converting unit 110. As shown in FIG. The detailed structure of the signal conversion unit 110 will be described in detail with reference to FIG.

2, the signal conversion unit 110 includes a wavelet transform unit 210, a second-order high-pass filter 215, and a second-order low-pass filter 220.

The wavelet transform unit 210 is means for performing discrete wavelet transform on the transformer secondary signal.

In the embodiment of the present invention, the secondary side discrete wavelet transform of the transformer secondary side signal will be mainly described. Accordingly, as shown in FIG. 2, the wavelet transform unit 210 may be composed of multi-stage filter banks 201a, 201b, 202a, and 202b.

In addition, it is assumed that the wavelet transform unit 210 performs DB2 wavelet transform in one embodiment of the present invention. As a matter of course, it is natural that the wavelet transform can clearly detect the peak of the result obtained by continuously decomposing the approximate information of the signal of the secondary side of the current transformer.

In order to perform a second-order discrete wavelet transform of the transformer secondary-side signal, the wavelet transformer 210 first decomposes the transformer secondary-side signal through the first-stage filter bank 201 and then through the second-stage filter bank 202 Secondary disassembly is possible.

The stage filter banks 201 and 202 included in the wavelet transform unit 210 include low pass filters 201a and 202a and high pass filters 201b and 202b, respectively.

A process of continuously passing through the multistage filter banks 201 and 202 included in the wavelet transform unit 210 to decompose the current signal of the current transformer will be briefly described below.

The first stage filter bank 201 includes one low-pass filter 201a and one high-pass filter 201b.

That is, the transformer secondary signal is decomposed into a low-frequency subband and a high-frequency subband through the low-pass filter 201a and the high-pass filter 201b of the first-stage filter bank 201, respectively.

It is natural that the wavelet transform unit 210 can derive the wavelet transform coefficient by passing the second-order signal of the transformer through the first-stage filter bank 201.

Since the detector 120 according to an embodiment of the present invention decomposes the approximate information of the current signal of the transformer secondary side and uses it to detect the current detector saturation, the second stage filter bank 202 is connected to the low- Frequency subband signal that has passed through the filter 201a and decomposes the signal into a low frequency subband and a high frequency subband through a low pass filter 202a and a high pass filter 202b, respectively.

Generally, information according to a signal of a low-frequency subband due to wavelet transform (i.e., a wavelet transform coefficient derived through a low-pass filter) is information about an overall approximation of an input signal (i.e., a transformer secondary signal) .

On the other hand, the information according to the signal of the high-frequency subband due to the wavelet transform (i.e., the wavelet transform coefficient derived through the high-pass filter) includes information on the detail of the input signal .

Accordingly, the current detector 130 for a current transformer according to an embodiment of the present invention detects the peak of the output signal by decomposing the approximate information of the secondary signal of the current transformer to detect the current saturation of the transformer, And the low-frequency sub-band of the sub-band can be output as an output signal.

Accordingly, the wavelet transform unit 210 can output the signal that has passed through the high-pass filter 202b of the second-stage filter bank 202 as the output signal to the detection unit 120. [

As shown in FIG. 3, the peak of the output signal output through the wavelet transform unit 210 may be detected to detect the current transformer saturation.

However, in order to further clarify the output signal for detecting the converter saturation, the output signal output through the wavelet transform unit 210 is output to the second-order high-pass filter 215 in one embodiment of the present invention.

The second high-pass filter 215 is coupled to the rear end of the wavelet transform unit 210. The second high-pass filter 215 receives the output signal output through the wavelet transformer 210 and filters the received output signal to pass only the designated high-frequency band. This makes it possible to clearly reveal the peak of the output signal output through the wavelet transformer 210. [

Here, the second high-pass filter 215 may be a second-order Butterworth high-pass filter.

3 illustrates an output signal that has passed through each configuration of the signal detecting unit 120. As shown in FIG.

3 (a) is a graph showing a transformer primary signal and a transformer secondary signal. Generally, when the signal of the secondary side of the current transformer is normal, the signal of the secondary side of the current transformer generates a periodic signal. The periodic signal has the same magnitude of the magnitude of the current.

However, as shown in Fig. 3 (a), when the current transformer secondary signal is an irregular signal, the current transformer secondary signal generally occurs in the abnormal state including current surge.

Accordingly, the output signal output through the wavelet transform unit 210 is passed through the second high-pass filter 215, and the instant at which the non-periodic signal is generated becomes prominent, thereby facilitating detection of the current transformer saturation .

3B is a graph showing a subband signal (i.e., an output signal) that has passed through the high-pass filter 202b of the second-stage filter bank of the wavelet transform unit 210. As shown in FIG.

As shown in FIG. 3 (b), it is also possible to detect a peak in the output signal output through the wavelet transformer 210, but this is not easy compared with FIG. 3 (c).

Accordingly, the output signal output through the wavelet transform unit 210 may be filtered through the second-order high-pass filter 215 to change the peak of the output signal so as to be easily detected, as in the embodiment of the present invention.

The method of detecting the current transformer saturation will be described in more detail in the description of the detection unit 120 in the following.

4 shows a signal conversion result according to a signal of a secondary side of a transformer generated according to a switching phenomenon according to reclosing of a preceding stage.

4A is a graph showing a transformer secondary signal and a transformer primary signal generated according to the reclosing phenomenon of the preceding stage. As shown in FIG. 4A, when the switching phenomenon such as the reclosing phenomenon occurs even though the current is not in the current saturated state of the current transformer, when the current signal of the current transformer secondary side is subjected to wavelet transform, An error is judged to be generated.

Therefore, in order to remove this, the output signal filtered through the second high-pass filter 215 is output to the second-order low-pass filter 220.

The second low-pass filter 220 is coupled to the rear end of the second high-pass filter 215. Accordingly, the second-order low-pass filter 220 filters the output signal output from the second-order high-pass filter 215 and outputs the filtered signal to the detector 120.

Here, the second-order low-pass filter 220 may be a second-order Butterworth low-pass filter like the second-order high-pass filter 215.

FIG. 5 illustrates an output signal of the transformer secondary signal when the reclosing phenomenon occurs in FIG. 4, after passing through a second high-pass filter 215 and then through a second low-pass filter 220.

4 and 5, it can be seen that the saturation detection error due to the switching phenomenon is eliminated in the output signal passed through the second-order low-pass filter 220, as shown in FIG.

The detector 120 receives the filtered output signal and detects a peak of a threshold value or more from the received output signal to detect a current detector saturation section.

Generally, current transformer saturation occurs after a fault moment occurs. Therefore, the detector 120 can set the first threshold value using the filter gain and the reference fault current (minimum fault current) in order to detect a fault moment in the output signal.

The first threshold value may be calculated using the following equation (1).

Figure 112015031490355-pat00001

Here, 0.00117 represents a gain obtained when a fundamental wave signal having a size of 1 is passed through a two-stage filter bank, a second-order high-pass filter, and a second-order low-pass filter. Also,

Figure 112015031490355-pat00002
Represents the expected reference fault current (minimum fault current).

The detection unit 120 can detect a point at which a peak exceeding the first threshold value occurs in the output signal as a fault instantaneous point.

Further, when detecting a peak exceeding the first threshold value in the output signal, the detecting unit 120 may detect a peak to be detected according to the phase angle of the current signal of the current transformer secondary side.

For example, when the current transformer secondary signal is 0 degree as shown in FIG. 3, the detection unit 120 can detect a positive peak at the time of peak detection above the threshold value in the output signal.

On the other hand, as shown in FIG. 6, when the signal of the secondary side of the current transformer is 180 degrees, the detection unit 120 detects a peak of a negative tone when the peak of the output signal is greater than a threshold value, have.

That is, the detection unit 120 may first set a first threshold value for detecting an instantaneous failure in the output signal, and may detect a peak in the output signal that exceeds the first threshold value, and determine the instant as a failure instantaneous point.

Next, the detection unit 120 detects the peak of the output signal after the failure moment, and sets the second threshold value to the peak. Here, the second threshold value is used for detecting the starting point of the current transformer saturation.

That is, the detection unit 120 can detect a peak point in the output signal that is equal to or higher than the second threshold value as a saturation start point.

3 to 6, the saturation end point corresponds to half of the maximum value (i.e., peak) of the output signal generated at the time of failure.

Therefore, the detection unit 120 can set the third threshold value for detecting the saturation end point to a value that is a half value of the peak of the output signal generated at the moment of failure.

Accordingly, the detection unit 120 can detect peaks in the output signal and detect the failure moment and the saturation interval (that is, the saturation start point and the saturation end point), respectively.

7 is a flowchart illustrating a method of detecting a current transformer saturation according to an embodiment of the present invention.

In step 710, the transformer saturation detecting apparatus 100 receives a transformer secondary signal and performs a secondary discrete wavelet transform on the transformer secondary signal.

At this time, the converter saturation detection apparatus 100 can perform discrete wavelet transform of a transformer secondary signal using a multistage filter bank, and then output a signal of an LH subband among a plurality of subbands as an output signal.

More specifically, the transformer saturation detection apparatus 100 can decompose a current transformer secondary signal into a low-frequency sub-band and a high-frequency sub-band using a first-stage filter bank.

Next, the current transformer saturation detection apparatus 100 can decompose the result of the decomposed low frequency sub-band through the first stage filter bank into a second low-frequency sub-band and a high-frequency sub-band, respectively, using a second-stage filter bank. Next, the current detector 130 of the current transformer saturation detector 100 outputs the decomposed result of the high-frequency subband of the second-stage filter bank as an output signal.

In step 715, the current transformer saturation detecting apparatus 100 filters the output signal according to the result of the second discrete wavelet transform through the second-order high-pass filter. At this time, as described above, the high-pass filter may be a second-order Butterworth high-pass filter.

As described above, the high-frequency band designated through the second-order high-pass filter is filtered and output, thereby making it possible to further clarify the frequency peak of the output signal according to the result of the second-order discrete wavelet transform.

Next, in step 720, the current transformer saturation detecting apparatus 100 filters the output signal filtered through the second-order high-pass filter through the second-order low-pass filter. Here, the second-order low-pass filter may be a second-order Butterworth low-pass filter, as described above.

Thus, filtering the output signal filtered through the second-order low-pass filter has the advantage of eliminating the current detector saturation detection error caused by the switching phenomenon such as reclosing phenomenon.

In step 725, current detector saturation detector 100 detects the current saturation and de-saturation by detecting a peak above the threshold in the filtered output signal.

To detect a current transformer saturation interval in the filtered output signal, the current transformer saturation detection device 100 first sets a first threshold for detecting a fault moment.

As already described above, the first threshold value can be set by multiplying the filter gain by the reference fault current (minimum fault current), as described in equation (1).

The current transformer saturation detecting apparatus 100 can detect a failure moment by detecting a positive peak value or a negative peak value of the filtered output signal exceeding the first threshold value in accordance with the phase angle of the current signal of the current transformer secondary side respectively.

According to another embodiment of the present invention, in order not to consider the phase angle of the current signal of the current transformer, the current transformer saturation detecting apparatus 100 takes an absolute value for the filtered output signal and then calculates a peak value The failure moment can be detected.

Then, the current transformer saturation detecting apparatus 100 can set the second threshold value and the third threshold value for the saturation start point and the saturation end point in the filtered output signal. The second threshold value may be set to a peak value of the output signal generated at the time of the failure, and the third threshold value may be set to a half value of the second threshold value, as described above.

Thereby, the current detector 130 for detecting the current of the transformer can detect the peak of the fault, the peak of the current at the fault, and the end point of the current saturation, respectively, by detecting the peak value exceeding the threshold value in the filtered output signal.

Meanwhile, the method of detecting a current transformer saturation according to an embodiment of the present invention may be implemented in a form of a program command that can be executed through a variety of means for electronically processing information, and may be recorded in a storage medium. The storage medium may include program instructions, data files, data structures, and the like, alone or in combination.

Program instructions to be recorded on the storage medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of software. Examples of storage media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, magneto-optical media and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as devices for processing information electronically using an interpreter or the like, for example, a high-level language code that can be executed by a computer.

The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

100: Current transformer saturation detection device
110: Signal conversion unit
120:
210: wavelet transform unit
201: First stage filter bank
201a: Low-pass filter of the first stage filter bank
201b: High-pass filter of the first stage filter bank
202: second stage filter bank
202a: Low-pass filter of the second stage filter bank
202b: High-pass filter of the second stage filter bank
215: Secondary high-pass filter
220: Secondary Low Pass Filter


Claims (10)

A wavelet transformer including a multistage filter bank and filtering the transformer secondary signal through the multistage filter bank and outputting the filtered signal as an output signal;
A second high-pass filter for filtering and outputting an output signal output from the wavelet transform unit; And
And a detector for detecting a current transformer saturation using a peak of an output signal filtered through the second high-pass filter,
Wherein:
A first threshold value is set by multiplying a reference fault current by a filter gain, a time point when the output signal filtered through the second high-pass filter exceeds the first threshold value is detected as a failure moment,
Wherein the peak value of the output signal filtered through the second high-pass filter generated at the instant of failure is set as a second threshold value for detecting the start point of saturation, and the second high- Setting a third threshold value for detecting the end point of the saturation to the half value of the peak of the output signal filtered through the filter,
Wherein the second high-pass filter detects a time point at which the magnitude of the output signal filtered through the second high-pass filter is equal to or greater than the second threshold value as a start point of saturation, And detects a point of time equal to or greater than the threshold value as the end point of the saturation. The method according to claim 1,
Wherein the wavelet transform unit comprises:
Stage filter bank,
Wherein each bank of filter stages comprises a low-pass filter and a high-pass filter, respectively. 3. The method of claim 2,
Wherein the wavelet transform unit comprises:
Wherein the approximate information of the second-order signal of the current transformer is continuously decomposed through the second-stage filter bank to output the filtered output signal through the multistage filter bank. 3. The method of claim 2,
Wherein the wavelet transform unit comprises:
Pass the low-pass filter and the high-pass filter of the first stage filter bank,
Passing a signal having passed through a low-pass filter of the first-stage filter bank to a low-pass filter and a high-pass filter of a second-stage filter bank,
Wherein the output signal filtered through the multi-stage filter bank is a current transformer secondary signal passed through the high-pass filter of the second stage filter bank. The method according to claim 1,
Wherein:
The point at which the (2n-1) -th peak is generated after the occurrence of the fault in the output signal filtered through the second-order high-pass filter is determined to be the starting point of the current transformer saturation, and the point at which the 2n- Respectively,
Wherein n is a natural number. The method according to claim 1,
Further comprising a second low-pass filter coupled to a downstream end of the second high-pass filter, for filtering an output signal having passed through the second high-pass filter and filtering the designated high-frequency band.

The method according to claim 6,
Wherein the filter gain is a gain when a fundamental wave signal having a size of 1 passes through the wavelet transform unit, the second high-pass filter, and the second low-pass filter. delete The method according to claim 1,
Wherein:
And detects a positive peak value or a negative peak value of the output signal filtered through the second high-pass filter according to a phase angle of the voltage at the time of failure, thereby detecting a current-saturated period of the current transformer. Filtering the secondary side signal of the current transformer through a multi-stage filter bank and outputting it as an output signal;
Filtering the output signal through a second-order high-pass filter and outputting the filtered signal; And
Detecting a current transformer saturation using a peak of the filtered output signal filtered through the second high-pass filter,
Wherein detecting the current transformer saturation comprises:
Multiplying a reference fault current by a filter gain to set a first threshold value and detecting a point in time at which the output signal filtered through the second high pass filter exceeds the first threshold as a fault moment;
Wherein the peak value of the output signal filtered through the second high-pass filter generated at the instant of failure is set as a second threshold value for detecting the start point of saturation, and the second high- Setting a third threshold value for detecting the end point of the saturation to a half value of the peak of the output signal filtered through the filter;
Wherein the second high-pass filter detects a time point at which the magnitude of the output signal filtered through the second high-pass filter is equal to or greater than the second threshold value as a start point of saturation, Detecting a point of time that is equal to or greater than a threshold value as the end point of the saturation.
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Cited By (2)

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CN107086551A (en) * 2017-06-20 2017-08-22 南京磐能新能源技术有限公司 A kind of system and method for distance protection malfunction when preventing CT saturations
CN107255760A (en) * 2017-06-21 2017-10-17 重庆新世杰电气股份有限公司 A kind of method and system for judging CT saturation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101317561B1 (en) * 2012-05-16 2013-10-11 용인송담대학교 산학협력단 Method for detecting ground fault of power line using wavelet transform

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100580428B1 (en) * 2004-10-11 2006-05-15 명지대학교 산학협력단 A compensation method for the distorted secondary current of a current transformer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101317561B1 (en) * 2012-05-16 2013-10-11 용인송담대학교 산학협력단 Method for detecting ground fault of power line using wavelet transform

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107086551A (en) * 2017-06-20 2017-08-22 南京磐能新能源技术有限公司 A kind of system and method for distance protection malfunction when preventing CT saturations
CN107255760A (en) * 2017-06-21 2017-10-17 重庆新世杰电气股份有限公司 A kind of method and system for judging CT saturation
CN107255760B (en) * 2017-06-21 2019-11-22 重庆新世杰电气股份有限公司 A kind of method and system judging CT saturation

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