JPH06258379A - Partial discharge detecting method - Google Patents

Abstract

PURPOSE:To cancel noises in signals by detecting partial discharge signals of arbitrary two positions, phase-inverting any one of the signals, and comparing the both. CONSTITUTION:A signal detected through a preamplifier 3, a superheterodyne receiver 5 from arbitrary electrodes 2 in two insulation joints 1 is compared with a signal detected through an amplifier 3, a receiver 5 and a phase inverting amplifier 7 from the other arbitrary electrode 3 by a comparison amplifier 8. The same local oscillation high frequencies are applied from a local oscillator controller 6 to the two receivers 5. When the two detection signals are both only noises, they are cancelled by the amplifier 8, and its output is zero. However, when either one has a partial discharge and a partial discharge signal is detected, only the discharge signal in which noise is removed is produced as an output of the amplifier 8. The output from which joint 1 it is output can be identified from a direction of the output signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial discharge detection method, and more particularly to a signal processing method of an insulation diagnosis method for a high voltage CV cable.

[0002]

2. Description of the Related Art Conventional detection of partial discharge, such as partial surface discharge due to a high electric field on the surface of an insulator, or internal discharge generated in voids or bubbles inside the insulator, is not detected in the signal. It was difficult because noise from generators, transformers, etc., crosstalk from communication lines laid in the same common groove as the CV cable, noise from railways, automobiles, etc. entered.

The noise, by its nature, varies with the passage of time. It is difficult to determine whether the fluctuation is due to the partial discharge or the fluctuation of the noise.

A conventional technique will be described below with reference to FIGS.

FIG. 3 is a schematic explanatory view of a conventional partial discharge detection method, and FIG. 4 is a diagram showing an output of a spectrum analyzer in the conventional partial discharge detection method.

In FIG. 3, reference numeral 1 denotes a cable metal sheet.
Insulation joint for reducing the induced voltage generated in the battery, 2 is a detection electrode for detecting partial discharge,
Reference numeral 3 is a preamplifier for amplifying the partial discharge signal, and 4 is a spectrum analyzer for measuring the signal amplified by the preamplifier.

The detection electrode 2 for detecting partial discharge is attached to the insulation joint 1, the preamplifier 3 amplifies the detected partial discharge signal, and the amplified signal is analyzed by the spectrum analyzer 4 and the fluctuation thereof is detected. The presence or absence of partial discharge was detected. As shown in FIG. 4, the output diagram of the spectrum analyzer 4 always contains noise and its variation at any frequency, and it was difficult to detect partial discharge.

[0008]

In the above-described conventional partial discharge detection method, there is a problem in that noise is always included in the signal, and the noise level and the partial discharge signal level are the same level, making it difficult to determine. Had.

Further, in the above-described conventional partial discharge detection method, there is always a noise fluctuation in the signal, and the level of the noise fluctuation varies from a short time (order of seconds to minutes) to a long time (year of order). There is a problem that it is impossible to accurately judge the signal of the partial discharge at any time.

The present invention has been made to solve the above-mentioned problems of the prior art, and solves the problem that it is difficult to distinguish between the noise contained in the signal and the partial discharge signal in the conventional measurement method, and the partial discharge is solved. It is an object of the present invention to provide a partial discharge detection method that detects only a signal.

[0011]

In order to achieve the above object, the structure of the partial discharge detection method according to the present invention has a structure in which a partial discharge signal at an arbitrary position and another arbitrary partial discharge signal are detected from the partial discharge detection at a plurality of positions. Partial discharge signal of the location is detected, the partial discharge signal of either one of the two locations is phase-inverted, the phase-inverted signal is compared with the partial discharge signal of the other location, and the partial discharge signals of both are compared. The internal noises are canceled each other so that only the partial discharge signals of the both are extracted.

[0012]

The function of each of the above technical means is as follows.

According to the configuration of the present invention, the partial discharge signal at an arbitrary location is phase-inverted, and the phase-inverted signal is compared with the partial discharge signal at another arbitrary location to cancel the noise with each other. Only the partial discharge detection signal can be taken out.

[0014]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic explanatory view of a partial discharge detection method according to an embodiment of the present invention, and FIG. 2 is a diagram showing an output of a spectrum analyzer 4 in the partial discharge detection method according to the embodiment of FIG. Is.

In FIG. 1, the same symbols as those in FIG. 5 is a superheterodyne receiver that filters the partial discharge detection signal amplified by the preamplifier 3, 6 is a local oscillator control circuit, 7 is a phase inversion amplifier that inverts the phase of the partial discharge detection signal, 8 Is
The super-heterodyne receiver 5 and the phase inversion amplifier 7 are compared with each other, and the partial discharge detection method can be implemented by the comparison amplifier which outputs the sum thereof.

Two insulation joints 1
When compared with the high voltage CV cable between the long axis and the long axis, the noises intruding from the outside and their temporal fluctuations are also the same because they are physically and electrically almost at the same positions.

Therefore, of the two insulation joints 1, a signal detected from any detection electrode 2 via the pre-reamp 3 and the superheterodyne receiver 5, and another detection electrode 2 from any pre-reamp 3 are used. , The superheterodyne receiver 5, and another signal detected through the phase inversion amplifier 7 are compared in a comparison amplifier 8.

In this case, needless to say, the same high frequency controlled by the local oscillator control circuit 6 is applied to the two superheterodyne receivers 5.

When the signal and the other signal are only noise, they are mutually canceled in the comparison amplifier 8 and the output of the comparison amplifier 8 becomes zero.

However, when there is a partial discharge part in either one and a partial discharge signal is detected, only the partial discharge signal can be taken out from the comparison amplifier 8 as an output signal.

From the direction of this output signal, it can be determined from which insulation joint the partial discharge signal is being output.

In practice, the high-voltage CV cable is often in three phases, and since there are three signals, they are compared with each other, and the reliability of partial discharge detection is obtained by the signals after comparison. Can be increased.

The present invention is not limited to this embodiment, and many modifications can be considered.

For example, instead of the super-heterodyne receiver for filtering the partial discharge signal, a filter tuning type, a multistage filter type, a Fourier transform type or the like may be used.

In practice, the double super-heterodyne receiver or the Fourier transform type is preferably used because the phase inversion of any one of the two signals is compared with any other signal. .

[0027]

As described above in detail, according to the present invention, it is possible to solve the problem that it is difficult to distinguish the noise contained in the signal from the partial discharge signal in the conventional measuring method, and detect only the partial discharge signal. It is possible to provide a method for detecting partial discharge.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a partial discharge detection method according to an embodiment of the present invention.

FIG. 2 is a diagram showing the output of a spectrum analyzer in the partial discharge detection method according to the embodiment of FIG.

FIG. 3 is a schematic explanatory view of a conventional partial discharge detection method.

FIG. 4 is a diagram showing an output of a spectrum analyzer in a conventional partial discharge detection method.

[Explanation of symbols]

 1 Insulation Joint 2 Detection Electrode 3 Preamplifier 4 Spectrum Analyzer 5 Superheterodyne Receiver 6 Local Oscillator Control Circuit 7 Phase Inversion Amplifier 8 Comparison Amplifier

Claims (1)

[Claims] 1. A method of detecting partial discharge at a plurality of locations, detecting a partial discharge signal at an arbitrary location and a partial discharge signal at another arbitrary location, and inverting the phase of one of the partial discharge signals at both locations. , The phase-inverted signal is compared with the partial discharge signal at the other location, and noises in the partial discharge signals of the both are canceled each other, so that only the partial discharge of the both is extracted. Discharge detection method.