JP2002281658A - Cause discriminating device for power transmission line failure equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically discriminate the cause of failure by a method where detected change of zero-phase current waveform is subjected to short time frequency analysis and patterned. SOLUTION: A comparison means is installed, where short-term Fourier transform of zero phase current waveform which is observed by a zero-phase current detector is performed, on the basis of time series data outputted from a sampling means, the mean value in each frequency of the short-term Fourier transform is performed, and a short-term Fourier transform of normal zero phase current waveform which is observed by a zero-phase current waveform detector is performed and compared with the main value. Thereby whether a zero-phase current waveform observed by the zero-phase current waveform detector is normal can be discriminated. That is, the mean value is an index showing the mean value of probability density distribution function, which makes a definite distribution in the case that zero-phase current waveform is normal, and makes the distribution different from the definite distribution, in the case that zero phase current waveform is not normal, so that discrimination is enabled by comparing the mean values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line failure cause determining apparatus used for determining a transmission line failure cause.

[0002]

2. Description of the Related Art A conventional circuit breaker breaking method will be described. FIG. 6 shows, for example, IEEJ technical report 5
FIG. 55 is a schematic diagram showing a configuration of a conventional transmission line failure cause determination method disclosed in No. 55 / July 1995, “Trends in Power Distribution Equipment Degradation Diagnosis Technology” / Issue of the Institute of Electrical Engineers of Japan / p. In the figure, 1 is a transformer for ground fault test, 2 is a transformer for short circuit test, 3 is a capacitor (capacitance to ground) that simulates the capacitance between ground, and 4 is a bus for ground fault test.

In FIG. 6, 5 is a CR voltage divider connected to the ground fault test bus A side, 6 is a CR voltage divider connected to the ground fault test bus B side, and 7 is a ground fault test bus C side. Is connected to the CR voltage divider, and 8 is the light C connected to the ground fault test bus A side.
T (current sensor), 9 is an optical CT (current sensor) connected to the ground fault test bus B side, 10 is an optical CT (current sensor) connected to the ground fault test bus C side, 11 is an earth CT test Is a high-frequency CT (high-frequency current sensor) for measuring a current caused by the occurrence of an artificial ground fault.

Further, in FIG. 6, reference numeral 13 denotes a voltage of the CR voltage divider 5, the CR voltage divider 6, the CR voltage divider 7, a current sensor 8, a current sensor 9, a current sensor 10, a current of the high-frequency current sensor 12, and an electric field sensor. A data recorder for recording each data of the electric field 17 and the magnetic field of the magnetic field sensor 18;
Each data of the voltage of the R voltage divider 5, the CR voltage divider 6, the CR voltage divider 7, the current sensor 8, the current sensor 9, the current sensor 10, the current of the high frequency current sensor 12, the electric field of the electric field sensor 17, and the magnetic field of the magnetic field sensor 18. Is a high-speed oscilloscope that displays.

In FIG. 6, 15 is a gap (artificial ground fault gap) for generating an artificial ground fault, and 16 is a gap for generating an artificial ground fault.
A bus bar for simulating capacitance to ground, which simulates the capacitance between ground and ground, 17 is an electric field sensor for measuring the electric field fluctuation generated in the artificial ground gap 15, and 18 is generated in the artificial ground gap 15 This is a magnetic field sensor that measures a changing magnetic field.

[0006] When a ground fault occurs, the entire waveform of the leakage current accompanying the ground fault is subjected to frequency analysis, and the cause is determined from the difference in the waveform of the frequency analysis result for each ground fault cause.

[0007]

The information of the cause of the ground fault exists at most about 20 milliseconds after the occurrence of the ground fault. Even if the whole of the ground fault waveform before and after the occurrence of the ground fault is frequency-analyzed, Most of the information is the commercial frequency of 60 Hz (50 Hz), and it is difficult to determine the cause of the failure. Since the conventional transmission line failure cause determination device is configured as described above,
There are many misjudgments in failure cause determination. This has been pointed out as a very serious problem for the safety of the distribution system.

The present invention has been made in view of the above, and provides a transmission line failure cause determining apparatus for automatically detecting the cause of a failure by patterning the detected zero-phase current waveform change by frequency analysis in a short time. The purpose is to:

[0009]

In order to achieve the above object, a transmission line failure cause determining apparatus according to the present invention comprises a current detecting means for detecting a zero-phase current of a transmission line, and a current detecting means for detecting a zero phase current of the transmission line. Sampling means for sampling the current signal obtained at predetermined time intervals and outputting a plurality of time-series data; computing means for performing a short-time Fourier transform of the current signal output from the sampling means; and the short-time Fourier transform Calculating means for calculating an average value for each frequency from 1 to M calculated by the above; an average value for each frequency from 1 to M calculated by the calculating means; and a current detected by the current detecting means. Comparing means for comparing the average value of each frequency from 1 to M when the signal is normal; and outputting a current state based on the comparison result of the comparing means. Comparison means, characterized in that and an alarm output means for outputting an alarm based on the comparison result of the comparing means.

That is, the short-time Fourier transform of the zero-phase current waveform is calculated based on the time-series data output from the sampling means, and the average value of each frequency of the short-time Fourier transform is calculated to calculate the zero-phase current waveform. This is to be compared with the average value in a normal state.

According to the present invention, the short-time Fourier transform of the zero-phase current waveform observed by the zero-phase current detector is calculated based on the time series data output from the sampling means, and the short-time Fourier transform of the short-time Fourier transform is calculated. By calculating the short-time Fourier transform of the average value for each frequency and the normal zero-phase current waveform observed by the zero-phase current detector, and providing comparison means for comparing the average value, the zero-phase current detector It becomes possible to distinguish whether the observed zero-phase current waveform is normal. In other words, the average value is an index indicating the average value of the probability density distribution function, and the probability density distribution function has a fixed distribution when the zero-phase current waveform is normal. The distinction can be made by comparing the values.

[0012] A transmission line failure cause determining apparatus according to the next invention comprises a current detecting means for detecting a zero-phase current of the transmission line;
Sampling means for sampling the current signal detected by the current detection means at predetermined time intervals and outputting a plurality of time-series data; and arithmetic means for executing a short-time Fourier transform of the current signal output from the sampling means And 1 to M calculated from the short-time Fourier transform
Calculating means for calculating a variance value for each frequency up to, and when the variance value for each frequency from 1 to M calculated by the calculating means and the current signal detected by the current detecting means are normal. Comparing means for comparing the variance value for each frequency from 1 to M; comparing means for outputting a current state based on the comparison result of the comparing means; and outputting an alarm based on the comparison result of the comparing means. Alarm output means.

That is, the short-time Fourier transform of the zero-phase current waveform is calculated based on the time-series data output from the sampling means, and the variance value of each frequency of the short-time Fourier transform is calculated to calculate the zero-phase current waveform. This is compared with the variance in the normal state.

According to this invention, the short-time Fourier transform of the zero-phase current waveform observed by the zero-phase current detector is calculated based on the time-series data output from the sampling means, and the short-time Fourier transform of the short-time Fourier transform is calculated. A short-time Fourier transform of the variance value for each frequency and the normal zero-phase current waveform observed by the zero-phase current detector is calculated and comparison means for comparing the variance value is provided. It becomes possible to distinguish whether the observed zero-phase current waveform is normal. That is, the variance value is an index indicating the variance value of the probability density distribution function.The probability density distribution function has a fixed distribution when the zero-phase current waveform is normal, but differs from the fixed distribution when the zero-phase current waveform is not normal. The distinction can be made by comparing the values.

According to another aspect of the present invention, there is provided a transmission line failure cause determining apparatus, comprising: a current detecting means for detecting a zero-phase current of the transmission line;
Sampling means for sampling the current signal detected by the current detection means at predetermined time intervals and outputting a plurality of time-series data; and arithmetic means for executing a short-time Fourier transform of the current signal output from the sampling means And 1 to M calculated from the short-time Fourier transform
Calculating means for calculating the skewness for each frequency up to the skewness for each frequency from 1 to M calculated by the calculating means and when the current signal detected by the current detecting means is normal. Comparing means for comparing the skewness of each frequency from 1 to M, comparing means for outputting a current state based on the comparison result of the comparing means, and outputting an alarm based on the comparison result of the comparing means Alarm output means.

That is, the short-time Fourier transform of the zero-phase current waveform is calculated based on the time-series data output from the sampling means, and the skewness of each frequency of the short-time Fourier transform is calculated to calculate the zero-phase current waveform. This is to be compared with the skewness in a normal state.

According to the present invention, the short-time Fourier transform of the zero-phase current waveform observed by the zero-phase current detector is calculated based on the time series data output from the sampling means, and the short-time Fourier transform is calculated. The skewness of each frequency and the short-time Fourier transform of the normal zero-phase current waveform observed by the zero-phase current detector are calculated, and the comparison means for comparing the skewness with the skewness is provided. It becomes possible to distinguish whether the observed zero-phase current waveform is normal. That is, the skewness is an index indicating the skewness of the probability density distribution function.The probability density distribution function has a fixed distribution when the zero-phase current waveform is normal, but differs from the fixed distribution when the zero-phase current waveform is not normal. By comparing the degrees, the above distinction can be made.

According to another aspect of the present invention, there is provided a transmission line failure cause determining apparatus, comprising: a current detecting means for detecting a zero-phase current of the transmission line;
Sampling means for sampling the current signal detected by the current detection means at predetermined time intervals and outputting a plurality of time-series data; and arithmetic means for executing a short-time Fourier transform of the current signal output from the sampling means And 1 to M calculated from the short-time Fourier transform
Calculating means for calculating the kurtosis for each frequency up to, and when the kurtosis for each frequency from 1 to M calculated by the calculating means and the current signal detected by the current detecting means are normal. Comparing means for comparing the kurtosis of each frequency from 1 to M, comparing means for outputting a current state based on the comparison result of the comparing means, and outputting an alarm based on the comparison result of the comparing means Alarm output means.

That is, the short-time Fourier transform of the zero-phase current waveform is calculated based on the time-series data output from the sampling means, the kurtosis of each frequency of the short-time Fourier transform is calculated, and the zero-phase current waveform is calculated. The comparison is made with the kurtosis in a normal state.

According to the present invention, the short-time Fourier transform of the zero-phase current waveform observed by the zero-phase current detector is calculated based on the time-series data output from the sampling means, and the short-time Fourier transform of the short-time Fourier transform is calculated. The kurtosis of each frequency and the short-time Fourier transform of the normal zero-phase current waveform observed by the zero-phase current detector are calculated, and the comparison means for comparing with the kurtosis is provided. It becomes possible to distinguish whether the observed zero-phase current waveform is normal. That is, the kurtosis is an index indicating the kurtosis of the probability density distribution function.The probability density distribution function has a fixed distribution when the zero-phase current waveform is normal, but differs from the fixed distribution when the zero-phase current waveform is not normal. By comparing the degrees, the above distinction can be made.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a transmission line failure cause determining apparatus according to the present invention will be described in detail.

Embodiment 1 FIG. 1 is a diagram showing a schematic configuration of a system including a transmission line failure cause determination device according to a first embodiment of the present invention. In the figure, the same reference numerals as those in the related art indicate the same or corresponding parts. Description is omitted.

In FIG. 1, reference numeral 20 denotes a zero-phase current waveform 1
9 that allows only an appropriate frequency band component to pass through;
1 is a zero-phase current waveform 19 passing through an appropriate frequency band.
An A / D converter 22 for sampling the zero-phase current waveform 19 amplified at an appropriate amplification factor at predetermined time intervals and performing analog-to-digital (A / D) conversion; 23 indicates a plurality of time-series data Y
_The normalization computing unit 24 that outputs _i (i = 1, 2,..., N) is a transmission line failure cause determination device that performs failure determination based on the time-series data Y _i .

In the figure, one zero-phase current waveform is represented by one, but actually, a three-phase zero-phase current waveform is targeted. Although the figure shows a three-phase zero-phase current waveform, a single-phase zero-phase current waveform has the same effect.

FIG. 2 is a diagram showing a detailed configuration of the transmission line failure cause determining device 24. In the drawing, reference numeral 26 denotes a zero-phase current based on the time series data Y _i output from the normalizing calculator 23. The short-time Fourier transform calculators 27, 28, and 29 that execute the short-time Fourier transform of the waveform are the results output from the short-time Fourier transform calculator 26, respectively, and 1, 2,. Frequency and 1, 2, ...,
It is represented by M times. The frequencies are (1) 27, (2) 28, and (j) 29, respectively. Reference numeral 30 denotes an average calculator (1) for calculating the average of the frequency (1) 27 output from the short-time Fourier transform calculator 26, 31
Are average calculators (2) and 32 that calculate the average of the frequency (2) 28 output from the short-time Fourier transform calculator 26
Is an average calculator (j) that calculates the average of the frequency (j) 29 output from the short-time Fourier transform calculator 26. Incidentally, j average calculators are set in advance.

Reference numeral 33 denotes a setting unit (1) for storing the average of the short-time Fourier transform frequency (1) 27 when the current is normally supplied, and 34 denotes an arithmetic unit (1) 30 Comparison of comparing the average of the short-time Fourier transform frequency (1) 27 of the zero-phase current waveform thus obtained with the average of the normal-time short-time Fourier transform frequency (1) 27 stored in the setting unit (1) 33 Vessel (1).

A setter (2) 35 stores the average of the short-time Fourier transform frequency (2) 28 when the current is normally supplied, and a setter (2) 36 is operated by an average calculator (2) 31. Comparison of the average of the short-time Fourier transform frequency (2) 28 of the zero phase current waveform thus obtained and the average of the normal-time short-time Fourier transform frequency (2) 28 stored in the setting unit (2) 35 Vessel (2).

A setter (j) 37 stores the average of the short-time Fourier transform frequency (j) 29 when the current is normally supplied, and a setter (j) 38 is operated by an average calculator (j) 32. Comparison of comparing the average of the short-time Fourier transform frequency (j) 29 of the obtained zero-phase current waveform with the average of the normal-time short-time Fourier transform frequency (j) 29 stored in the setting unit (j) 37 Vessel (j).

In the figure, three frequencies, such as frequency (1) 27, frequency (2) 28, and frequency (j) 29, are representatively represented. However, in reality, j frequencies are obtained. Can be Similarly, three comparators, such as a comparator (1) 34, a comparator (2) 36, and a comparator (j) 38, are shown as representatives, but actually j comparators are required. . In addition, although the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 are represented by three, they are actually represented by j.
Setting devices are required.

Reference numeral 39 denotes a comparator (1) 34 and a comparator (2)
36,..., A setting device (M) for storing an allowable pattern when a current is normally supplied to the comparator (j) 38
It is. Reference numeral 40 denotes a comparison between the comparison result of the comparator (1) 34, the comparator (2) 36,..., The comparator (j) 38 and the normal allowable pattern stored in the setting unit (M) 39. Comparator (M), and 41 is a comparator (M) 4
This is a transmission line failure cause discriminator that outputs a transmission line failure cause discrimination based on the comparison result of 0.

Next, the operation will be described. First, in FIG. 1, the A / D converter 22 samples the zero-phase current waveform measured by the current converter at predetermined time intervals, and performs analog-to-digital conversion. Y _i (i = 1, 2,..., N) is output.

[0032] When the plurality of time-series data Y _i is input in the transmission line failure cause determination device 24, a short time in the transmission line failure cause determination unit 24 Fourier transform operator 26
There, as shown below, to divide the short period from the time-series data Y _i.

[0033]

(Equation 1)

Next, the short-time Fourier transform calculator 26
Executes a short-time Fourier transform on the divided short-time section data. The result of the short-time Fourier transform is indicated by frequencies 1, 2,..., J.

[0035]

(Equation 2)

The result of the short-time Fourier transform is frequency 1,
, J, the average calculator (1) 30, the average calculator (2) 31, and the average calculator (j) 32 in the transmission line fault cause determination device 24 are as follows: , frequency 1, 2, ..., each mean mu ₁ ¹ of j, μ ₁ ^2, ·
Calculate μ ₁ ^j .

[0037]

(Equation 3)

The average μ ¹¹ , the average μ ₁₁ , the average calculator (2) 31 and the average calculator (j) 32 are used.
When μ ₁ ² ,... μ ₁ ^j are calculated, the comparator (1) 3
4. The comparator (2) 36 and the comparator (j) 38 determine the average of the short-time Fourier transform frequencies 1, 2,..., J when the zero-phase current waveform is normal, using a setting unit ( 1) 33, setter (2) 35, setter (j) input from 37, the computed _{^{μ 1 1, μ 1 2,}} ··· μ 1 j and the frequency 1 of the normal, & .. Compare with the average of j. Here, the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 have the short-time Fourier transform frequencies 1, 2,... When the zero-phase current waveform is normal. , J are stored, but the average in a normal state calculated by an external device (not shown) may be stored.

The comparator (1) 34 and the comparator (2)
36, a comparator (j) 38 is mu ₁ ¹ computed, mu ₁ ^2, · ·
· Mu ₁ ^j and a result of comparing the average of the normal, for example, computed ^{_{μ 1 1, μ 1 2,}} ··· μ 1 j is the mean of the normal 3
When the number exceeds twice, it is determined as abnormal and output to the comparator (M) 40.

Here, the reason why the average of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform can be distinguished between the normal state and the abnormal state in the current input state will be briefly described.
Frequency 1, 2 of short-time Fourier transform of zero-phase current waveform,
..., j is a filter for each corresponding frequency,
The average of the filtered time-series data is normally distributed around a certain value. If it becomes abnormal, the specific frequency or the average of all frequencies deviates from the average in the case where it is normal. Since this way of deviation depends on how abnormal current is applied, it is possible to determine normal / abnormal by comparing the average.

The comparator (M) 40 determines whether the comparator (1) 34, the comparator (2) 36, or the comparator (j) 38 has determined whether the frequency is normal or abnormal for each frequency. The final judgment is determined by comparing with the pattern. This determination is stored in the setting device (M) 39 according to the target. For example, the simplest setting criterion is a setting in which even if one frequency is abnormal, the final judgment is abnormal.

Finally, when the comparator (M) 40 determines that there is an abnormality, the transmission line failure cause determiner 41 displays a signal to clarify that the circuit breaker has been started and that an abnormal current has been applied. An error is displayed on a device (not shown), or a signal or the like is output on a monitoring device (not shown) for monitoring a plant, etc., to end a series of processes. .

As described above, according to the first embodiment, based on the average of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform, which can be an index for determining normality / abnormality, Since it is configured to determine whether the current is supplied normally or abnormally, the determination can be made in a short time.

Embodiment 2 Hereinafter, a second embodiment according to the present invention will be described. FIG. 3 is a diagram illustrating a schematic configuration of a transmission line failure cause determination device according to the second embodiment of the present invention.

FIG. 3 is a diagram showing a detailed configuration of the transmission line fault cause determining device 24 shown in FIG.
6, a short-time Fourier transform calculator for calculating a short-time Fourier transform of a zero-phase current waveform based on the time-series data Y _i output from the normalization calculator 23 via the A / D converter 22; 28 and 29 are the results output from the short-time Fourier transform operation unit 26, respectively, 1, 2,.
, J frequencies and times of 1, 2,..., M, and are represented as frequency (1) 27, frequency (2) 28, and frequency (j) 29, respectively. 42 is a variance calculator (1) for calculating the variance of the frequency (1) 27 output from the short-time Fourier transform calculator 26, and 43 is a frequency (2) 28 output from the short-time Fourier transform calculator 26. Are the dispersion computing units (2) and 44 which compute the variance of the frequency (j) 29 output from the short-time Fourier transform computing unit 26. Note that j distributed arithmetic units are set in advance.

Reference numeral 33 denotes a setting unit (1) for storing the variance of the short-time Fourier transform frequency (1) 27 when a current is normally supplied, and 34 is operated by a variance calculator (1) 42 To compare the variance of the short-time Fourier transform frequency (1) 27 of the obtained zero-phase current waveform with the variance of the normal-time short-time Fourier transform frequency (1) 27 stored in the setting unit (1) 33. Vessel (1).

Numeral 35 denotes a setting unit (2) for storing the variance of the frequency (2) 28 of the short-time Fourier transform when a current is normally supplied, and 36 is operated by a variance arithmetic unit (2) 43. A comparison that compares the variance of the short-time Fourier transform frequency (2) 28 of the obtained zero-phase current waveform with the variance of the normal-time short-time Fourier transform frequency (2) 28 stored in the setting unit (2) 35. Vessel (2).

Further, 37 is a setter (j) for storing the variance of the frequency (j) 29 of the short-time Fourier transform when the current is normally supplied, and 38 is a variance calculator (j) 44
The dispersion of the short-time Fourier transform frequency (j) 29 of the zero-phase current waveform calculated by the above and the normal-time short-time Fourier transform frequency (j) 29 stored in the setting unit (j) 37
Is a comparator (j) that compares the variances of.

In the figure, three frequencies, such as frequency (1) 27, frequency (2) 28, and frequency (j) 29, are representatively represented, but actually, j frequencies are obtained. . Similarly, three comparators, such as a comparator (1) 34, a comparator (2) 36, and a comparator (j) 38, are shown as representatives, but actually j comparators are required. . In addition, although the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 are represented by three as a representative, in actuality j
Setting devices are required.

Reference numeral 39 denotes a comparator (1) 34 and a comparator (2)
36,. . . , A setting unit (M) for storing an allowable pattern when a current is normally supplied to the comparator (j) 38
It is. 40 is a comparator (1) 34, a comparator (2) 3
6,. . . The comparators (M) and 41 for comparing the comparison result of the comparator (j) 38 with the normal allowable pattern stored in the setting unit (M) 39, based on the comparison result of the comparator (M) 40. It is a transmission line failure cause discriminator that outputs a transmission line failure cause discrimination.

Next, the operation will be described. First, in FIG. 1, the A / D converter 22 samples the zero-phase current waveform measured by the current converter at predetermined time intervals, performs analog-to-digital conversion, and outputs a plurality of waveforms through the normalization arithmetic unit 23. Sequence data Y _i (i = 1, 2,..., N)
Is output.

[0052] Then, when the plurality of time-series data Y _i is input in the transmission line failure cause determination device 24, a short time in the transmission line failure cause determination unit 24 Fourier transform operator 26
There, as shown below, to divide the short period from the time-series data Y _i.

[0053]

(Equation 1)

Next, the short-time Fourier transform calculator 26 executes a short-time Fourier transform on the divided short-time data. The short-time Fourier transform result is indicated by frequencies 1, 2,..., J.

[0055]

(Equation 2)

The result of the short-time Fourier transform is frequency 1, 2,
.., J, the transmission line failure cause determination device 2
4, the distributed computing unit (1) 42, the distributed computing unit (2) 4
3, the dispersion calculator (j) 44, as described below, the frequency 1, 2, each distributed mu ₂ ¹ of ^{_{j, μ 2 2, ··· μ}} 2
Calculate ^j .

[0057]

(Equation 4)

Then, the variance μ 21, the variance μ ₂ ¹ ,
When μ ₂ ² ,... μ ₂ ^j is calculated, the comparator (1) 3
4. The comparator (2) 36 and the comparator (j) 38 determine the variance of the short-time Fourier transform frequencies 1, 2,..., J when the zero-phase current waveform is normal. ) 33, setter (2) 35, setter (j) input from 37, the computed mu ₂ ^1, mu ₂ ^2, · · · mu ₂ ^j and the frequency 1 and 2 normal, ... • Compare the variance of j. Here, the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 have the short-time Fourier transform frequencies 1, 2,... When the zero-phase current waveform is normal. , J are stored, but the normal variance calculated by an external device (not shown) may be stored.

Then, the comparator (1) 34 and the comparator (2)
36, a comparator (j) 38 is mu ₂ ¹ computed, mu ₂ ^2, · ·
· Mu ₂ ^j and the result of comparing the variance of the normal, for example, the calculated ^{_{μ 2 1, μ 2 2,}} ··· μ 2 j is the variance of the normal 3
When the number exceeds twice, it is determined as abnormal and output to the comparator (M) 40.

Here, the reason why the variance of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform makes it possible to distinguish between normal and abnormal current-input states will be briefly described.
Frequency 1, 2 of short-time Fourier transform of zero-phase current waveform,
..., j is a filter for each corresponding frequency,
The variance of the filtered time-series data is normally distributed around a certain value. When an abnormality occurs, the variance of a specific frequency or all frequencies deviates from the variance in a normal case. Since this way of deviation depends on how abnormal current is applied, it is possible to determine normal / abnormal by comparing the variances.

The comparator (M) 40 determines the result of the judgment by the comparator (1) 34, the comparator (2) 36, and the comparator (j) 38 and determines whether the frequency is normal or abnormal for each frequency which is predetermined in the normal state. The final judgment is determined by comparing with the pattern. This determination is stored in the setting device (M) 39 according to the target. For example, the simplest setting criterion is a setting in which even if one frequency is abnormal, the final judgment is abnormal.

Finally, when the comparator (M) 40 judges that there is an abnormality, the transmission line failure cause discriminator 41 displays a signal to clarify that the circuit breaker has been started and that an abnormal current has been applied. An error is displayed on a device (not shown), or a signal or the like is output on a monitoring device (not shown) for monitoring a plant, etc., to end a series of processes. .

As described above, according to the second embodiment, the current is determined based on the variance of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform which can be used as an index for determining normality / abnormality. Since it is configured to judge whether the input is normal or abnormal, the judgment can be made in a short time.

Embodiment 3 Hereinafter, a third embodiment according to the present invention will be described. FIG. 4 is a diagram illustrating a configuration of a transmission line failure cause determining apparatus according to a third embodiment of the present invention. In the figure, the same reference numerals as those in the related art denote the same or corresponding parts, and a description thereof will be omitted. I do.

FIG. 4 is a diagram showing a detailed configuration of the transmission line failure cause determination device 24 shown in FIG.
Reference numeral 6 denotes a short-time Fourier transform calculator for executing a short-time Fourier transform of a zero-phase current waveform based on the time-series data Y _i output from the normalization calculator 23 via the A / D converter 22; 28 and 29 are the results output from the short-time Fourier transform operation unit 26, respectively, 1, 2,.
, J frequencies and times of 1, 2,..., M, and are represented as frequency (1) 27, frequency (2) 28, and frequency (j) 29, respectively. 45 is a skewness calculator (1) for calculating the skewness of the frequency (1) 27 output from the short-time Fourier transform calculator 26, and 46 is a frequency (2) output from the short-time Fourier transform calculator 26. The skewness calculator (2) for calculating the skewness of 28) and 47 are skewness calculators (j) for calculating the skewness of the frequency (j) 29 output from the short-time Fourier transform calculator 26. Note that this skewness calculator is j
Set in advance.

In FIG. 4, reference numeral 33 denotes a setter (1) for storing the skewness of the frequency (1) 27 of the short-time Fourier transform when a current is normally supplied, and 34 denotes a skewness calculator (1). ) 45. The skewness of the frequency (1) 27 of the short-time Fourier transform of the zero-phase current waveform calculated by 45 and the setting unit (1) 3
3 is a comparator (1) for comparing the skewness of the frequency (1) 27 of the short-time Fourier transform in a normal state stored in 3.

A setter (2) 35 stores the skewness of the short-time Fourier transform frequency (2) 28 when current is normally supplied, and a skewness calculator (2) 46 And the skewness of the short-time Fourier transform frequency (2) 28 of the zero-phase current waveform and the skewness of the normal-time short-time Fourier transform frequency (2) 28 stored in the setting unit (2) 35 And a comparator (2) for comparing

Further, 37 is a setter (j) for storing the skewness of the frequency (j) 29 when the current is normally supplied, and 38 is a zero set by the skewness calculator (j) 47. Frequency (j) of short-time Fourier transform of phase current waveform
This is a comparator (j) for comparing the skewness of No. 29 with the skewness of the frequency (j) 29 of the short-time Fourier transform in a normal state stored in the setter (j) 37.

In the figure, three frequencies such as frequency (1) 27, frequency (2) 28, and frequency (j) 29 are shown as representatives, but j frequencies are actually obtained. . Similarly, three comparators, such as a comparator (1) 34, a comparator (2) 36, and a comparator (j) 38, are shown as representatives, but actually j comparators are required. . In addition, although the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 are represented by three, they are actually represented by j.
Setting devices are required.

Reference numeral 39 denotes a comparator (1) 34 and a comparator (2)
36,. . . , A setting unit (M) for storing an allowable pattern when a current is normally supplied to the comparator (j) 38
It is. 40 is a comparator (1) 34, a comparator (2) 3
6,. . . A comparator 41 for comparing the comparison result of the comparator (j) 38 with the normal allowable pattern stored in the setting unit (M) 39. A failure cause determination is performed based on the comparison result of the comparator (M) 40. This is a transmission line failure cause discriminator that outputs.

Next, the operation will be described. First, the zero-phase current waveform measured by the current converter is converted to an A / D converter 2
2 performs sampling at predetermined time intervals, performs analog-to-digital conversion, and outputs a plurality of time-series data Y _i (i = 1, 2,..., N) via the normalization calculator 23.

When a plurality of time series data Y _i are input to the transmission line failure cause determination device 24, the short-time Fourier transform calculator 26 in the transmission line failure cause determination device 24
Divides the time-series data Y _i into short time sections as shown below.

[0073]

(Equation 1)

Next, the short-time Fourier transform operation unit performs a short-time Fourier transform on the divided short-time data. The short-time Fourier transform result is frequency 1,
2,..., J.

[0075]

(Equation 2)

The result of the short-time Fourier transform is frequency 1, 2,
.., J, the transmission line failure cause determination device 2
Skewness calculator (1) 45 and skewness calculator (2) 4
6, skewness calculator (j) 47 is, as shown below, frequency 1, 2, each of skewness mu ₃ ¹ of ^{_{j, μ 3 2, ··· μ}} 3
Calculate ^j .

[0077]

(Equation 5)

[0078] Then, skewness computing unit (1) 45, skewness computing unit (2) 46, the skewness mu ₃ ¹ by skewness computing unit (j) 47,
When μ ₃ ² ,... μ ₃ ^j are calculated, the comparator (1) 3
4. The comparator (2) 36 and the comparator (j) 38 set the skewness of the short-time Fourier transform frequencies 1, 2,..., J when the zero-phase current waveform is normal. 1) 33, setter (2) 35, setter (j) input from 37, the computed ^{_{μ 3 1, μ 3 2,}} ··· μ 3 j and the frequency 2 in the normal state, - ··· Compare with the skewness of j. Here, the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 have the short-time Fourier transform frequencies 1, 2,... When the zero-phase current waveform is normal. , J are stored, but the normal state skewness calculated by an external device (not shown) may be stored.

Then, the comparator (1) 34 and the comparator (2)
36, a comparator (j) 38 is mu ₃ ¹ has been calculated, mu ₃ ^2, · ·
· Mu ₃ ^j and the result of comparing the skewness of the normal, for example, computed ^{_{μ 3 1, μ 3 2,}} ··· μ 3 j of skewness of the normal 3
When the number exceeds twice, it is determined as abnormal and output to the comparator (M) 40.

Here, the reason why the skewness of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform can be distinguished between the normal state and the abnormal state in the current input state will be briefly described.
Frequency 1, 2 of short-time Fourier transform of zero-phase current waveform,
..., j is a filter for each corresponding frequency,
If the skewness of the filtered time series data is normal,
Distributed around a certain value. When an abnormality occurs, the skewness of a specific frequency or all frequencies deviates from the skewness of a normal case. Since this way of deviation depends on how abnormal current is applied, normality / abnormality can be determined by comparing the skewness.

The comparator (M) 40 determines whether the comparator (1) 34, the comparator (2) 36, or the comparator (j) 38 has determined whether or not each of the frequencies is normal or abnormal. The final judgment is determined by comparing with the pattern. This determination is stored in the setting device (M) 39 according to the target. For example, the simplest setting criterion is a setting in which even if one frequency is abnormal, the final judgment is abnormal.

Finally, when the comparator (M) 40 judges that there is an abnormality, the transmission line failure cause discriminator 41 displays a signal to clarify that the circuit breaker has been started and that an abnormal current has been applied. An error is displayed on a device (not shown), or a signal or the like is output on a monitoring device (not shown) for monitoring a plant, etc., to end a series of processes. .

As described above, according to the third embodiment, based on the skewness of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform, which can be an index for judging normality / abnormality. Is configured to determine whether the current supply is normal or abnormal, so that the determination can be made in a short time.

Embodiment 4 Next, a fourth embodiment according to the present invention will be described. FIG. 5 shows a configuration of a transmission line failure cause determining apparatus according to a fourth embodiment of the present invention. In the figure, the same reference numerals as those in the related art denote the same or corresponding parts, and a description thereof will be omitted. I do.

FIG. 5 is a diagram showing a detailed configuration of a transmission line fault cause determining device 24 according to the fourth embodiment. In the drawing, reference numeral 26 denotes an A / D converter The short-time Fourier transform calculators 27, 28, and 29 that calculate the short-time Fourier transform of the zero-phase current waveform based on the time-series data Y _i output from 22 are output from the short-time Fourier transform calculator 26, respectively. As a result,
.., J frequencies and times of 1, 2,..., M, and are represented by frequency (1) 27 and frequency (2) 2 respectively.
8, frequency (j) 29.

Further, in FIG. 5, reference numeral 48 denotes the frequency (1) 27 output from the short-time Fourier transform
The kurtosis calculators (1) and 49 for calculating the kurtosis of the frequency (2) 28 output from the short-time Fourier transform calculator 26
The kurtosis calculator (2), 50 for calculating the kurtosis of the frequency is the frequency (j) 29 output from the short-time Fourier transform calculator 26.
Is a kurtosis calculator (j) that calculates the kurtosis of. Note that j kurtosis calculators are set in advance.

The setting unit (1) 33 stores the kurtosis of the frequency (1) 27 of the short-time Fourier transform when the current is supplied normally, and the kurtosis calculator (1) 48 The kurtosis of the short-time Fourier transform frequency (1) 27 of the zero-phase current waveform and the kurtosis of the normal-time short-time Fourier transform frequency (1) 27 stored in the setting unit (1) 33 Is a comparator (1) for comparing.

Further, 35 is a setting device (2) for storing the kurtosis of the short-time Fourier transform frequency (2) 28 when current is normally supplied, and 36 is a kurtosis calculator (2) 49
The kurtosis of the short-time Fourier transform frequency (2) 28 of the zero-phase current waveform calculated by the above and the normal-time short-time Fourier transform frequency (2) 28 stored in the setting unit (2) 35
A comparator (2) for comparing the kurtosis.

A setting unit (j) 37 stores the kurtosis of the frequency (j) 29 when the current is supplied normally.
Numeral 38 denotes the kurtosis of the frequency (j) 29 of the short-time Fourier transform of the zero-phase current waveform calculated by the kurtosis calculator (j) 50 and the kurtosis at the normal time stored in the setter (j) 37. The comparator (j) compares the kurtosis of the frequency (j) 29 of the Fourier transform.

In the figure, three frequencies are represented as frequency (1) 27, frequency (2) 28 and frequency (j) 29, but j frequencies are actually obtained. . Similarly, three comparators (1) 34, comparators (2) 36, and comparators (j) 38 are shown as representatives, but actually j comparators are required. . In addition, although the setting device (1) 33, the setting device (2) 35, and the setting device (j) 37 are represented by three as a representative, in actuality j
Setting devices are required.

In FIG. 5, reference numeral 39 denotes a comparator (1) 34, a comparator (2) 36,. . . , Comparator (j)
38 is a setting unit (M) for storing an allowable pattern when a current is normally supplied. 40 are comparators (1) 34, comparators (2) 36,. . . , Comparator (j)
Comparators (M) and 41, which compare the comparison result of 38 with the allowable pattern at the normal time stored in the setting unit (M) 39, output failure cause determination based on the comparison result of the comparator (M) 40. This is a transmission line failure cause discriminator.

Next, the operation will be described. First, the zero-phase current waveform measured by the current converter is converted to an A / D converter 2
2 performs sampling at predetermined time intervals, performs analog-to-digital conversion, and outputs a plurality of time-series data Y _i (i = 1, 2,..., N) via the normalization calculator 23.

[0093] When the plurality of time-series data Y _i is input in the transmission line failure cause determination device 24, a short time in the transmission line failure cause determination unit 24 Fourier transform operator 26
Divides the time-series data Y _i into short time sections as shown below.

[0094]

(Equation 1)

Next, the short-time Fourier transform operation unit performs a short-time Fourier transform on the divided short-time data. The short-time Fourier transform result is frequency 1,
2,..., J.

[0096]

(Equation 2)

The result of the short-time Fourier transform is frequency 1, 2,
.., J, the transmission line failure cause determination device 2
Kurtosis calculator (1) 48 and kurtosis calculator (2) 4 in 4
9, kurtosis calculator (j) 50 is, as shown below, frequency 1, 2, each kurtosis mu ₄ ¹ of ^{_{j, μ 4 2, ··· μ}} 4
Calculate ^j .

[0098]

(Equation 6)

[0099] Then, kurtosis calculator (1) 48, kurtosis calculator (2) 49, the kurtosis mu ₄ ¹ by kurtosis calculator (j) 50,
When μ ₄ ² ,... μ ₄ ^j is calculated, the comparator (1) 3
4. The comparator (2) 36 and the comparator (j) 38 set the kurtosis of the short-time Fourier transform frequencies 1, 2,..., J when the zero-phase current waveform is normal. 1) 33, setter (2) 35, setter (j) input from 37, the computed ^{_{μ 4 1, μ 4 2,}} ··· μ 4 j and each frequency 1,2 in the normal, &・ ・ Compare with the kurtosis of j.

Here, the setting device (1) 33 and the setting device (2)
35, the setting device (j) 37 has a short-time Fourier transform frequency of 1, 2,... When the zero-phase current waveform is normal.
Although the kurtosis of j is stored, the kurtosis in a normal state calculated by an external device (not shown) may be stored.

Then, the comparator (1) 34 and the comparator (2)
36, a comparator (j) 38 is mu ₄ ¹ has been calculated, mu ₄ ^2, · ·
· Mu ₄ ^j and the result of comparing the kurtosis of the normal, for example, computed ^{_{μ 4 1, μ 4 2,}} ··· μ 4 j is the kurtosis of the normal 3
When the number exceeds twice, it is determined as abnormal and output to the comparator (M) 40.

Here, the reason why the kurtosis of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform can be distinguished from the normal state and the abnormal state in the current input state will be briefly described.
Frequency 1, 2 of short-time Fourier transform of zero-phase current waveform,
..., j is a filter for each corresponding frequency,
The kurtosis of the filtered time-series data is normally distributed around a certain value. When an abnormality occurs, the kurtosis of a specific frequency or all frequencies deviates from the kurtosis of a normal case. Since this deviation depends on how the abnormal current is supplied, normality / abnormality can be determined by comparing the kurtosis.

The comparator (M) 40 determines whether the comparator (1) 34, the comparator (2) 36, or the comparator (j) 38 has a normal / abnormal condition for each frequency which is determined in advance during normal operation. The final judgment is determined by comparing with the pattern. This determination is stored in the setting device (M) 39 according to the target. For example, the simplest setting criterion is a setting in which even if one frequency is abnormal, the final judgment is abnormal.

Finally, when the comparator (M) 40 determines that there is an abnormality, the transmission line failure cause discriminator 41 displays a signal to clarify that the circuit breaker has been started and that an abnormal current has been applied. An error is displayed on a device (not shown), or a signal or the like is output on a monitoring device (not shown) for monitoring a plant, etc., to end a series of processes. .

As described above, according to the fourth embodiment, based on the kurtosis of the frequencies 1, 2,..., J of the short-time Fourier transform of the zero-phase current waveform which can be an index for judging normality / abnormality. Is configured to determine whether the current supply is normal or abnormal, so that the determination can be made in a short time.

[0106]

As described above, according to the present invention, the average of the frequencies 1, 2,..., J of the short-time Fourier transform of the current waveform based on the time-series data output from the sampling means is calculated. Since the current is compared with the normal average, the situation can be determined at a higher speed than the conventional one, and the cause of the transmission line failure can be determined at a higher speed. Also, by using the average value, the calculation time can be reduced.

According to the next invention, the variance of the short-time Fourier transform frequencies 1, 2,..., J of the current waveform based on the time series data output from the sampling means is calculated, and Was configured to compare with the variance of
This makes it possible to determine the situation at a higher speed as compared with the conventional one, and it is possible to determine the cause of the transmission line failure at a higher speed. By using the variance value, the sensitivity of a phenomenon in which an abnormality appears in the variation can be improved.

According to the next invention, the skewness of the frequencies 1, 2,..., J of the short-time Fourier transform of the current waveform based on the time-series data output from the sampling means is calculated, and when the current is normal Because it was configured to compare with the skewness of
This makes it possible to determine the situation at a higher speed as compared with the conventional one, and it is possible to determine the cause of the transmission line failure at a higher speed. By adopting the skewness, it is possible to improve the sensitivity of the phenomenon in which anomalies appear in the bias.

According to the next invention, the kurtosis of the frequencies 1, 2,..., J of the short-time Fourier transform of the current waveform based on the time-series data output from the sampling means is calculated, and when the current is normal Because it was configured to compare with the kurtosis of
This makes it possible to determine the situation at a higher speed as compared with the conventional one, and it is possible to determine the cause of the transmission line failure at a higher speed. By using the kurtosis, the sensitivity of the phenomenon in which an abnormality appears in the spread can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a system including a transmission line failure cause determination device according to the present invention.

FIG. 2 is a block diagram illustrating a detailed configuration of a transmission line failure cause determination device according to the first embodiment of the present invention;

FIG. 3 is a block diagram illustrating a detailed configuration of a transmission line failure cause determination device according to a second embodiment of the present invention;

FIG. 4 is a block diagram illustrating a detailed configuration of a transmission line failure cause determination device according to a third embodiment of the present invention;

FIG. 5 is a block diagram illustrating a detailed configuration of a transmission line failure cause determination device according to a fourth embodiment of the present invention;

FIG. 6 is a diagram illustrating a configuration of a conventional transmission line failure cause determination device.

[Explanation of symbols]

20 filters, 21 amplifiers, 22 A / D converters,
23 standardized computing unit, 24 transmission line failure cause determination device,
26 short-time Fourier transform calculator, 27 frequency (1), 28 frequency (2), 29 frequency (j), 3
0 Average calculator (1), 31 Average calculator (2), 32
Average calculator (j), 33 setter (1), 34 comparator (1), 35 setter (2), 36 comparator (2),
37 setter (j), 38 comparator (j), 39 setter (M), 40 comparator (M), 41 transmission line fault cause discriminator, 42 distributed operation unit (1), 43 distributed operation unit (2 ), 44 variance calculator (j), 45 skewness calculator (1), 46 skewness calculator (2), 47 skewness calculator (j), 48 kurtosis calculator (1), 49 kurtosis calculation Unit (2), 50 kurtosis calculator (j).

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akihide Nozue, 1 Higashi-Shinmachi, Higashi-ku, Nagoya City, Aichi Prefecture Inside (72) Inventor Tsutomu Yamazaki 1 Higashi-Shinmachi, Higashi-ku, Nagoya City, Aichi Prefecture Chubu Electric Power Co., Inc. F term (reference) 2G015 AA27 CA21 2G033 AA01 AC02 AD14 AF04 AF05 AG14 5G058 BB02 BC16 BD14 CC02

Claims (4)

[Claims] 1. A current detecting means for detecting a zero-phase current of a transmission line, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals, and outputting a plurality of time-series data; Calculating means for performing a short-time Fourier transform of the current signal output from the sampling means; calculating means for calculating an average value for each frequency from 1 to M calculated by the short-time Fourier transform; Comparing means for comparing the average value for each frequency from 1 to M calculated by the means with the average value for each frequency from 1 to M when the current signal detected by the current detecting means is normal; A comparison unit that outputs a current state based on a comparison result of the comparison unit; an alarm output unit that outputs an alarm based on a comparison result of the comparison unit; Transmission line failure cause determination apparatus characterized by comprising. 2. Current detecting means for detecting a zero-phase current of a transmission line, sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals, and outputting a plurality of time-series data; Calculating means for performing a short-time Fourier transform of the current signal output from the sampling means; calculating means for calculating a variance for each frequency from 1 to M calculated by the short-time Fourier transform; Comparing means for comparing a variance value for each frequency from 1 to M calculated by the means with a variance value for each frequency from 1 to M when the current signal detected by the current detecting means is normal; A comparison unit that outputs a current state based on a comparison result of the comparison unit; an alarm output unit that outputs an alarm based on a comparison result of the comparison unit; Transmission line failure cause determination apparatus characterized by comprising. 3. Current detecting means for detecting a zero-phase current of a transmission line, sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals, and outputting a plurality of time-series data; Calculating means for performing a short-time Fourier transform of the current signal output from the sampling means; calculating means for calculating a skewness for each frequency from 1 to M calculated by the short-time Fourier transform; Comparing means for comparing the skewness for each frequency from 1 to M calculated by the means with the skewness for each frequency from 1 to M when the current signal detected by the current detecting means is normal; A comparison unit that outputs a current state based on a comparison result of the comparison unit; and an alarm output unit that outputs an alarm based on the comparison result of the comparison unit. Transmission line failure cause determination apparatus characterized by. 4. A current detecting means for detecting a zero-phase current of a transmission line, a sampling means for sampling a current signal detected by the current detecting means at predetermined time intervals, and outputting a plurality of time-series data; Calculating means for performing a short-time Fourier transform of the current signal output from the sampling means; calculating means for calculating a kurtosis for each frequency from 1 to M calculated by the short-time Fourier transform; Comparing means for comparing the kurtosis for each frequency from 1 to M calculated by the means with the kurtosis for each frequency from 1 to M when the current signal detected by the current detecting means is normal; A comparison unit that outputs a current state based on a comparison result of the comparison unit; and an alarm output unit that outputs an alarm based on the comparison result of the comparison unit. Transmission line failure cause determination apparatus characterized by.