JPH05312887A - Partial discharge detection device for electric appliance - Google Patents

Abstract

PURPOSE:To surely and speedily detect partial discharge generated in a coil without being influenced by noise, with a relatively simple constitution. CONSTITUTION:A current detecting means 4 is provided corresponding to each phase of coil 1 of a transformer, and the detection signal is outputted to a phase adjusting circuit 5. In the circuit 5 paired detection signals are integrated so that they are adjusted to have a same phase to cancel the signal components. The signal components as well as noise signal components are to be eliminated almost so that in the case where a signal by partial discharge is included only the signal remains. In a processing display circuit 6, the output signal level from the circuit 5 is compared with a reference level and thereby generation of partial discharge can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting partial discharge of electric equipment for detecting partial discharge generated in windings of electric equipment.

[0002]

2. Description of the Related Art In electrical equipment having windings such as transformers and rotating electric machines, insulating papers and organic polymer materials such as polyethylene terephthalate, varnish, and resin are widely used as insulating materials for windings. It is used. In the case of a winding insulation-treated with these organic polymer materials, there is a possibility that a partial discharge may occur in the winding and the insulation performance may deteriorate. Therefore, conventionally, in designing a transformer or the like, consideration has been given to prevent partial discharge from occurring in the winding as much as possible.

However, in spite of the design for suppressing the occurrence of such partial discharge, partial discharge may occur in the winding due to long-term operation. In such a case, it is necessary to promptly detect the occurrence of the partial discharge and take appropriate measures.

Therefore, conventionally, several methods have been proposed as a device for detecting a partial discharge generated in a winding. For example, there is a method of directly detecting a minute pulse current due to partial discharge flowing in a ground wire of a device, and Japanese Patent Application No.
As disclosed in Japanese Laid-Open Patent Application No. 3-231194, a method of detecting an electromagnetic wave generated by partial discharge, or as disclosed in Japanese Patent Application No. 62-123916, the light generated by partial discharge is used by using an optical fiber or the like. There is a way to detect.

[0005]

However, in the various detection methods described above, not only the detection signal is weak but also the noise resistance is low, so that amplification of the detection signal or reduction of noise contained in the detection signal is required. However, there is a drawback in that the overall structure of the device is complicated. Further, in particular, separating and reducing noise is a major technical problem.

The present invention has been made in view of the above circumstances, and an object thereof is to reliably and quickly generate a partial discharge in a winding with a relatively simple structure and without being affected by noise as much as possible. (EN) Provided is a partial discharge detection device for an electric device capable of detecting the electric discharge.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, a partial discharge detecting device for an electric device according to the present invention is provided with a plurality of current detecting devices provided for each phase of a winding in the electric device. Means, a signal synthesizing circuit for synthesizing two detection signals of the detection signals output from the current detecting means so that the signal components cancel each other, and a part based on the output signal output from the signal synthesizing circuit. It is configured to include a determination unit that determines the occurrence of discharge.

[0008]

Each current detecting means detects the current of the corresponding phase of the winding, and the detection signal is output to the signal synthesizing circuit. At this time, if partial discharge occurs in one phase of the winding, the detection signal of that phase will include a signal due to partial discharge in the signal component, whereas the phase detection signal of the phase in which partial discharge has not occurred The detection signal does not include a signal due to partial discharge. Further, various noise signals are always superposed on the signal component in the detection signal of each phase.

Thus, in the signal synthesizing circuit, of the detection signals from the respective current detecting means, there are two detection signals, that is, the detection signal of the phase in which partial discharge has occurred and the detection signal of the phase in which partial discharge has not occurred. The detection signals are combined so that the signal components cancel each other out. Then, the signal component and the noise signal superimposed on the signal component are almost removed, and only the signal due to the partial discharge remains. Then, the determining means can detect the occurrence of the partial discharge by determining the occurrence of the partial discharge based on the output signal from the signal combining circuit.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a gas insulation transformer will be described below with reference to the drawings.

First, in FIG. 1 showing the overall electrical configuration, the winding 1 of the transformer is composed of first to third windings 1a and 1a.
It is constructed by star-connecting b and 1c, is insulated by polyethylene terephthalate, is wound around an iron core (not shown), and is housed in a tank filled with sulfur hexafluoride (SF6). One ends of the first to third windings 1a, 1b, 1c in the winding 1 are connected to the U-phase, V-phase and W-phase of the three-phase AC power supply.

Then, the first to third windings 1a, 1
A coupling impedance (Zc) is provided at one end of b and 1c.
2 and the discharge detection impedance (Zd) 3 are connected in series. These coupling impedances 2
And current detection means 4 by the discharge detection impedance 3
Is composed of.

The detection signal of each current detection means 4 is output from the discharge detection impedance 3 to a phase matching circuit 5 as a signal combining circuit. The phase matching circuit 5 matches the two detection signals of the detection signals of the respective current detection means 4 so as to have the same phase and synthesizes them by the differential amplifier, so that a signal component will be described later. Has a function of synthesizing so as to cancel each other.

The output signal from the phase matching circuit 5 is output to the processing display circuit 6 which constitutes the discriminating means. The processing / display circuit 6 has a function of determining whether or not partial discharge has occurred based on the output signal from the phase matching circuit 5, and displaying the determination result.

Next, the operation of the above structure will be described with reference to FIGS. Of these, FIG. 2 shows an example of the detection signals Φ1, Φ2, Φ3 of the current of the discharge detection impedance 3 connected to each phase of U, V, W, and FIG. 3 shows the output signals of the phase matching circuit 5. An example is shown.

It is assumed that a partial discharge is generated in the first winding 1a of the winding 1 corresponding to the U phase, for example, during the operation of the transformer. In such a case, the U-phase detection signal Φ1
As shown in FIG. 2, the main signal component 7 includes a noise signal 8 and a current pulse signal 9 depending on the magnitude of partial discharge.
And are superimposed (the noise signal 8 and the signal 9 due to the partial discharge are indicated by straight lines for convenience). On the other hand, Φ2, which is the V-phase detection signal in which partial discharge is not generated, and Φ3, which is the W-phase detection signal, have a waveform in which only the noise signal 8 is superimposed on the main signal component 7, and the signal due to partial discharge is generated. The ingredient of is not included.

In the phase matching circuit 5, the above-described detection signals Φ1, from the discharge detection impedance 3 of each phase.
Φ2 and Φ3 are input. Then, in the phase matching circuit 5, two detection signals among these three detection signals Φ1, Φ2, Φ3 are matched in phase and combined by a differential amplifier.

At this time, when the V-phase detection signal Φ2 and the W-phase detection signal Φ3 in which partial discharge is not generated are matched in the same phase and combined by the differential amplifier, the main signal component 7
Are canceled out and the noise signal 8 superimposed on the signal component 7 is also canceled out, so that the output signal output from the phase matching circuit 5 becomes extremely weak corresponding to the difference between the noises.

On the other hand, U in which partial discharge occurs
When the phase detection signal Φ1 and the V-phase detection signal Φ2 in which partial discharge does not occur are matched in the same phase and combined by the differential amplifier, the main signal component 7 and the signal component 7
Although the noise signal 8 superimposed on is almost canceled out, only the signal 9 due to the partial discharge remains. Therefore, as shown in FIG. 3, the output signal id output from the phase matching circuit 5 is almost the signal 9 due to the partial discharge.

In the processing display circuit 6, the reference level 10 is set in advance, and the level of the output signal id output from the phase matching circuit 5 is compared with the reference level 10 to cause partial discharge. It is possible to determine whether it has occurred. Further, in the processing display circuit 6, the discrimination result is displayed on a display device (not shown), and the user confirms the display,
It is possible to know whether or not partial discharge has occurred.

As described above, according to the present embodiment, the current detection means 4, the phase matching circuit 5 and the processing display circuit 6 are comparatively simple in structure, and the partial discharge is prevented from being affected by noise as much as possible. Occurrence can be detected reliably and promptly.

Although the above-described embodiment is applied to the gas-insulated transformer, the present invention is not limited to this. For example, an oil-filled transformer, a molded transformer, an electric machine having a winding, such as a rotary electric machine. Can be applied to.

[0023]

As is apparent from the above description, the present invention provides a plurality of current detecting means provided corresponding to each phase of the winding in the electric equipment, and outputs from these current detecting means. A signal synthesizing circuit that synthesizes two detection signals among the detection signals so that the signal components cancel each other, and a determining unit that determines the occurrence of partial discharge based on the output signal output from the signal synthesizing circuit. With this configuration, it is possible to reliably and quickly detect the partial discharge that occurs in the winding with a relatively simple structure and without being affected by noise as much as possible. Play.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a current detection signal of each discharge detection impedance.

FIG. 3 is a waveform diagram showing an output signal of a phase matching circuit.

[Explanation of symbols]

1 is a winding wire, 4 is a current detecting means, 5 is a phase matching circuit (signal combining circuit), 6 is a processing display circuit (discriminating means), 7 is a signal component, 8 is a noise signal, 9 is a signal by partial discharge, 10
Is the reference level.

Claims (1)

[Claims] 1. A plurality of current detection means provided corresponding to each phase of a winding in an electric device, and two detection signals of the detection signals output from these current detection means are signal components. A signal combining circuit that combines so as to cancel each other,
A partial discharge detection device for an electric device, comprising: a determination unit that determines the occurrence of partial discharge based on the output signal output from the signal synthesis circuit.