JPH08105928A - Partial discharge intensity measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] To eliminate background noise components as much as possible, to improve the measurement sensitivity of partial discharge and to improve the measurement accuracy. A partial discharge detection sensor 1, an A / D converter 2 for converting an input signal 22a from the partial discharge detection sensor 1 into a digital signal, and a digital signal obtained by the A / D converter 2 are provided. Fourier transform to obtain frequency distribution F
The FT converter 3, the differencer 4 for making a difference between the frequency distribution 23a obtained by this FFT converter and the stored frequency distribution 23b, and an integrator for obtaining the area of an arbitrary frequency band of the differenced frequency distribution 25. 5 and 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial discharge intensity measuring device for obtaining the intensity of partial discharge for diagnosing abnormality of electric power equipment.

[0002]

2. Description of the Related Art As one of means for obtaining the intensity of a partial discharge generated inside a power device, an electromagnetic wave emitted from the power device to the outside by the partial discharge is received by an antenna, and based on the received signal. There is a way to analyze.

Conventionally, as this analysis method, a voltage waveform of an input signal including many high frequency band components received by an antenna is converted into an envelope waveform, and an integral value of the envelope waveform at any time, that is, a voltage Obtain the time area and use it as the intensity of partial discharge, or expand the input signal to the intensity for each frequency with a spectrum analyzer, and use the intensity of a fixed frequency in this expanded intensity spectrum to determine the partial discharge. A method of determining strength is used.

[0004]

In such a conventional method, the background noise is included in the input signal for analysis, and it is difficult to accurately measure the intensity of the partial discharge. .

Further, since the frequency distribution and the magnitude of the electromagnetic wave generated by the partial discharge change depending on the circuit configuration of the electric power equipment and the generation place in the electric power equipment, the intensity of the fixed frequency and the true partial electric discharge are generated. There is a problem that the intensity of partial discharge cannot be accurately measured because of poor correlation with intensity.
Therefore, the present invention removes background noise components as much as possible to improve measurement accuracy.

[0006]

According to a first aspect of the present invention, there is provided a sensor for detecting partial discharge, an A / D converter for converting an input signal from the sensor for detecting partial discharge into a digital signal, and the A / D conversion. Of a digital signal obtained by the FFT converter to obtain a frequency distribution, a difference device for making a difference between the frequency distribution obtained by the FFT converter and the saved frequency distribution, and a difference frequency distribution And an integrator for determining the area of any frequency band.

According to another aspect of the present invention, there is provided a first partial discharge detection sensor, a first A / D converter for converting an input signal from the partial discharge detection sensor into a digital signal, and the A / D converter. A first FFT converter for Fourier transforming the obtained digital signal to obtain a frequency distribution, a second sensor for detecting partial discharge, and a second signal for converting an input signal from the sensor for detecting partial discharge into a digital signal. , And a second FFT converter that Fourier transforms the digital signal obtained by this A / D converter to obtain the frequency distribution, and obtains these two FFT converters.
A difference device for obtaining the difference from the frequency band distribution and an integrator for obtaining the area of a predetermined frequency band portion of the difference signal are provided.

According to another aspect of the present invention, there is provided a sensor for detecting partial discharge,
An A / D converter that converts the input signal from the partial discharge detection sensor into a digital signal, and a data separator that cuts the digital signal obtained by the A / D converter in a predetermined time interval and outputs two channels And two FFT converters that respectively Fourier transform two digital signals output via this data separator to obtain a frequency distribution, and a difference device that obtains the difference between the frequency distributions obtained by these two FFT converters. And an integrator that finds the area of a predetermined frequency band portion of the difference signal.

[0009]

According to the partial discharge intensity measuring device of the present invention having the above-described structure, the analog signal input by the partial discharge detecting sensor is converted into a digital signal by the A / D converter. The time component is expanded into the frequency distribution by the FFT converter. The differencer subtracts the signal previously expanded and stored in the frequency distribution from the signal newly expanded in the frequency distribution. Here, the signal that has been developed and stored in advance in the frequency distribution and has only the background noise can be output from the differentiator as a partial discharge signal component. The area of a predetermined frequency band of this frequency is obtained by an integrator, and this can be measured as the intensity of the partial discharge signal.

According to a second aspect of the present invention, the first partial discharge detection sensor is installed in a place sufficiently distant from the partial discharge detection target, and the second partial discharge detection sensor is installed in the partial discharge detection target. The analog signal obtained by inputting to the first sensor for detecting partial discharge is A / A as a background noise component.
It is converted into a digital signal by the D converter, further developed into a frequency distribution by the FFT converter and sent to the difference unit.

An analog signal obtained by inputting to the second sensor for detecting partial discharge is converted into a digital signal by an A / D converter as a partial discharge signal including background noise, and further frequency distribution is performed by an FFT converter. It is expanded to and sent to the differentiator. The differencer takes the difference between the frequency distribution input and expanded from the first partial discharge detection sensor and the frequency distribution input and expanded from the second partial discharge detection sensor, whereby only the partial discharge signal component is obtained. The frequency distribution of can be output. Further, the area of a predetermined frequency band of this frequency distribution is obtained by the integrator, and this can be measured as the intensity of the partial discharge signal.

According to a third aspect of the present invention, the analog signal input by the partial discharge detection sensor is converted into a digital signal by the A / D converter, and this digital signal is cut by the data separator at predetermined time intervals, and two time intervals are obtained. Two channels are output as signals. The two time interval signals are expanded into frequency distributions by the corresponding FFT converters and sent to the difference unit. The differencer takes the difference between the frequency distribution from the first time interval signal and the frequency distribution from the second time interval signal, and further, the area of the predetermined frequency band of the frequency distribution difference output from the integrator. Is required.

In general, an A / D converter accumulates an analog signal input by a sensor for detecting partial discharge at arbitrary time intervals, A / D converts it, and outputs it. However, it measures at or above an arbitrary input level. As a trigger, this can be set to the median value of the signal accumulation time section. Therefore, by setting the input level to be the measurement trigger to an arbitrary value higher than the input level of background noise, A /
Of the digital signals output from the D converter, the first half of the time segment can be output as a background noise component and the second half can be output as a component including a partial discharge signal.

Since the partial discharge signals are not generated continuously, this setting is possible. Therefore, by the data separator, the first time division signal in the first half and the second time division signal in the second half can be treated as a signal having a background noise component, and the second time division signal can be treated as a signal containing a partial discharge component. become able to.

As described above, the two time division signals are F
By processing with the FT converter, the subtractor, and the integrator, it is possible to measure the weekly lotion distribution of only the partial composite of the new partial discharge and the intensity of the partial discharge signal from the integrator.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the partial discharge intensity measuring apparatus of the present invention in claim 1 and shows an example of a spectrum at each signal processing stage. First
The analog signal 22b obtained by inputting the signal of only the background noise component to the partial discharge detection sensor 1 is A /
It is converted into a digital signal by the D converter 2, further Fourier-transformed by the FFT converter 3 and developed into the frequency distribution 23b. This is saved in the differentiator 4.

Next, an analog signal 22a containing an arbitrary partial discharge signal component obtained by inputting to the partial discharge detection sensor 1
Is converted into a digital signal by the A / D converter 2 in the same manner as described above, further Fourier-transformed by the FFT converter 3, expanded into the frequency distribution 23a, and input to the difference unit 4. Differentiator 4
Then, the difference between the previously stored frequency distribution 23b and the next input frequency distribution 23a is calculated, and the frequency distribution 25 of only the partial discharge signal component is output. In the integrator 5,
The area of the frequency band portion of the predetermined partial discharge of the frequency distribution 25 is obtained, and this is output as the intensity of the partial discharge.

FIG. 2 shows an embodiment in the case of claim 2 and shows an example of a spectrum at each signal processing stage. The analog signal 22a including the partial discharge signal component obtained by inputting to the partial discharge detection sensor 1a installed in the partial discharge detection target is converted into a digital signal by the A / D converter 2a, and Fourier-transformed by the FFT converter 3a. Is expanded to the frequency distribution 23a. On the other hand, the analog signal 22b of the background noise obtained by inputting to the partial discharge detection sensor 1b installed at a place sufficiently distant from the partial discharge detection target is converted into a digital signal by the A / D converter 2b, and the FFT converter is obtained. Fourier transform is performed by 3b to develop the frequency distribution 23b.

The frequency distribution 23a of the signal containing the partial discharge signal component and the frequency distribution 23b of the signal containing only the background noise component are sent to the differentiator 4, where the frequency distribution 23a of the signal containing the partial discharge signal component. And the frequency distribution 23b of the signal having only the background noise component are calculated, and the frequency distribution 2 having only the partial discharge signal component is obtained.
5 is output. In the integrator 5, the area of the frequency band portion of the predetermined partial discharge of the frequency distribution 25 is obtained, and this is output as the intensity of the partial discharge.

FIG. 3 shows an embodiment in the case of claim 3,
It is shown with an example of the spectrum at each signal processing stage. The analog signal 22 including the partial discharge signal component obtained by inputting to the partial discharge detection sensor 1 is converted into a digital signal by the A / D converter 2, but the voltage level of the measurement trigger in the A / D converter is backed up. By setting the voltage at an arbitrary voltage level greater than that of the ground noise voltage level at the center of the immediate hair time interval, the data separator 6 causes the time interval signal 26a including the partial discharge signal component and the time interval signal 26b including only the background noise component to be generated. Can be separated into The time interval signal 26a including the partial discharge signal component and the time interval signal 26b including only the background noise component are the FFT converter 3a and the FFT converter 3, respectively.
b, and is subjected to Fourier transform respectively to be expanded into a signal frequency distribution 23a including a partial discharge signal component and a background noise component only signal frequency distribution 23b.

The frequency distribution 23a of the signal containing the partial discharge signal component and the frequency distribution 23b of the signal containing only the background noise component are sent to the differentiator 4, and the frequency distribution 23a of the signal containing these partial discharge signal components and The difference from the frequency distribution 23b of the signal containing only the background noise component is calculated, and the frequency distribution 25 containing only the partial discharge signal component is obtained.
Is output. In the integrator 5, the area of the frequency band portion of the predetermined partial discharge of the frequency distribution 25 is obtained, and this is output as the intensity of the partial discharge.

An antenna or a capacitor electrode can be used as the partial discharge detection sensor.

[0023]

EFFECTS OF THE INVENTION The intensity of partial discharge generated by an electric power device is adjusted to the frequency distribution of electromagnetic waves and its magnitude which vary depending on the constituent circuit of the electric power device and the place where partial discharge occurs, by removing background noise around the device. Regardless,
The partial discharge intensity can be measured more accurately.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a partial discharge intensity measuring device of the present invention, and is shown together with an example of a spectrum at each processing stage.

FIG. 2 is a diagram showing another example of the partial discharge intensity measuring device of the present invention, and is shown together with an example of a spectrum at each processing stage.

FIG. 3 is a diagram showing still another example of the partial discharge intensity measuring device of the present invention, and is shown together with an example of the spectrum at each processing stage.

[Explanation of symbols]

 1, 1a, 1b Partial discharge detection sensor 2, 2a, 2b A / D converter 3, 3a, 3b FFT converter 4 Difference device 5 Integrator 6 Data separator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Watanabe 1 at 20 Kitakanzan, Otaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Electric Power Research Laboratory (72) Inventor Hirofumi Suzuki Nishi Kasugai West, Aichi 3-1, Yoshino-cho, Bibishima-cho Takadake Manufacturing Co., Ltd. Technical Development Center

Claims (3)

[Claims] 1. A partial discharge detection sensor and an A / D for converting an input signal from the partial discharge detection sensor into a digital signal.
A converter, an FFT converter that Fourier transforms a digital signal obtained by this A / D converter to obtain a frequency distribution, and a difference that makes a difference between the frequency distribution obtained by this FFT converter and the stored frequency distribution. Discharge intensity measuring device comprising: a container and an integrator for obtaining the area of an arbitrary frequency band of the frequency distribution obtained by the difference. 2. A first partial discharge detection sensor, a first A / D converter for converting an input signal from the partial discharge detection sensor into a digital signal, and this A / D converter. A first FFT converter for Fourier transforming a digital signal to obtain a frequency distribution, a second partial discharge detection sensor, and a second A / D for converting an input signal from the partial discharge detection sensor into a digital signal. A converter and a second FFT converter for Fourier-transforming the digital signal obtained by the A / D converter to obtain a frequency distribution, and the frequency obtained by the first and second FFT converters. A partial discharge intensity measuring device comprising a differencer for obtaining a difference in distribution and an integrator for obtaining an area of a predetermined frequency band portion of the differenced signal. 3. A sensor for detecting partial discharge and an A / D for converting an input signal from the sensor for detecting partial discharge into a digital signal.
A converter, a data separator that cuts the digital signal obtained by this A / D converter in a predetermined time interval and outputs two channels, and two digital signals output through this data separator. Fourier transform of two to obtain the frequency distribution, a difference device to obtain the difference of the frequency distribution obtained by these two FFT converters, and of the difference signal, a predetermined frequency band part A partial discharge intensity measuring device having an integrator for obtaining an area.