JPH04313074A - Abnormality detecting apparatus for rotary electric machine - Google Patents

Abstract

PURPOSE:To obtain an abnormality detecting apparatus which detects the partial discharging generated with the abnormality of the stator winding of a rotary electric machine highly sensitively and highly accurately and can monitor abnormality all the time. CONSTITUTION:A plurality of reflector antennas 14 and 15 are arranged in the circumferential direction at positions facing the cross-sectional surfaces of the parts which are protruding outward from the end part of a fixed stator core 2 at the end part of a stator winding at the inner wall surface of a stator frame 11 of a rotary electric machine 10. The detected signals of the antennas are inputted into an abnormality detector 20 comprising an amplifier circuit, a filter circuit, a discharge detecting and operating circuit, an abnormality judging circuit and a display circuit.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detection device for a rotating electrical machine that can detect and constantly monitor abnormalities caused by insulation deterioration of stator windings.

0002

BACKGROUND OF THE INVENTION In recent years, the scale of plants in general industries has continued to increase in size, and along with this, rotating electric machines have also become larger and the number of installed machines has also increased.

[0003] Therefore, such a rotating electric machine is particularly required to have high reliability, so maintenance and inspection must be performed reliably to prevent sudden accidents such as dielectric breakdown.

Conventionally, as a method for determining the insulation deterioration of a rotating electric machine, for example, for a stator, after stopping the operation of the rotating electric machine, a high voltage is applied to the windings to determine various electrical characteristics (insulation resistance, alternating current current, etc.). , dielectric loss angle, partial discharge, etc.) and estimate the degree of deterioration of the insulation in each part. A mechanical method is used to determine the mechanical damage state of the insulation part and the deterioration state of the winding fixing force by visual inspection or hammering sound.

However, in order to determine deterioration using these methods, it is necessary not only to stop the operation of the rotating electric machine but also to disconnect the line, and in some cases, it is also necessary to remove the rotor. For this reason, performing deterioration determination using such a series of methods requires a great deal of time, effort, and expense, and has the disadvantage that frequent deterioration determination tests are difficult to conduct. In addition, implementing such a method may require time for preparation, so it has the disadvantage that it cannot adequately deal with cases where deterioration progresses rapidly.

In order to eliminate such inconveniences, a partial discharge detection device for electrical equipment has been proposed in which a metal conductor is placed as a partial discharge detection antenna near the insulated winding of the electrical equipment.

FIG. 5 is a perspective explanatory view showing a conventional partial discharge detection device for electrical equipment disclosed in Japanese Utility Model Application Publication No. 55-51775, and FIG. 6 is a block diagram thereof. In Figure 5,
1 is the stator, 2 is the stator core, 3 is the stator winding end, 4
is the antenna wire for partial discharge detection. This antenna wire 4
The output from the antenna wire 4 is guided to the detection circuit 6 via the lead wire 5 as shown in FIG. The normal voltage frequency component is removed through the partial discharge counter 8, and the partial discharge is measured by entering the partial discharge counter 8.

However, subsequent research results have revealed that high-frequency currents caused by partial discharges propagating within the stator windings are significantly attenuated within the windings. For example, Figure 7
Magazine: IEE PROCEEDINGS, VOL.
132, Pt. B.No. 5, SEPTEMBER, 1
985 is a characteristic diagram of the signal level propagating in the winding for each frequency band. Characteristic curve A is 20-100
kHz, B is 20-300kHz, C is 20-1000
kHz, D is the characteristic of the frequency band of 20-3000 kHz. As is clear from the figure, the signal attenuation within the winding is significant, especially in the high frequency band that is effective for detecting electromagnetic waves, the signal level decreases by 1/2 to 1 during propagation of 1 to 2 turns within the winding.
It can be seen that the detection sensitivity decreases by attenuation of /10.

[0009]

[Problems to be Solved by the Invention] A conventional partial discharge detection device for detecting partial discharge in electrical equipment is constructed as described above, and a high frequency current based on partial discharge propagating within the stator winding is transmitted to the stator. Attenuation within the windings is significant, and antennas placed in the stator of rotating electrical machines have low gain, and the detection sensitivity is particularly poor when detecting partial discharge signals that occur at a distance from the antenna. Yes, also
Conventionally, high-frequency signals were detected in a frequency band of approximately 1 MHz or less, but considering the time required for signal processing, there was a problem that multiple signals generated within a few microseconds could not be detected separately, resulting in poor measurement accuracy. there were.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide an abnormality detection device for a rotating electrical machine that can constantly monitor abnormalities in stator windings with high detection sensitivity and measurement accuracy. shall be.

[0011]

[Means for Solving the Problems] An abnormality detection device for a rotating electric machine according to the present invention uses an antenna to detect radiated electromagnetic waves based on partial discharge generated due to an abnormality in the stator winding, and detects the abnormality in the stator winding. , and is located on the inner wall surface of the stator frame housing the stator at a position opposite to the cross section of the portion of the stator winding that protrudes outside the stator core slot.
A plurality of directional microwave band antennas are arranged circumferentially.

0012

[Operation] The abnormality detection device for a rotating electrical machine of the present invention has an antenna disposed at a position on the inner wall surface of the stator frame, facing the cross section of the portion of the stator winding that protrudes outside the stator core slot. Therefore, a sufficient insulation distance can be provided from the high-voltage stator winding, and the reliability of the rotating electrical machine will not be reduced. Furthermore, by detecting radiated electromagnetic waves in the microwave band, a small antenna with directivity and large gain can be used, which is less susceptible to noise and improves detection sensitivity. In addition, since signals in a higher frequency band than before are detected, errors caused by overlapping of multiple high frequency signals can be reduced and the time resolution of detection is improved.

[0013]

EXAMPLES Example 1 An example of the present invention will be described below with reference to the drawings. Figure 1
1 is a cross-sectional configuration diagram showing an abnormality detection device for a rotating electrical machine according to a first embodiment of the present invention. 10 is a rotating electric machine, in this case a generator, which includes a stator frame 11, a stator core 2, and a stator winding 1.
The rotor 13 includes a stator 1 and a rotor 13. The stator winding 12 is housed in a slot groove provided in the stator core 2 and is wound therein, and the portion that comes out of the stator core 2 for winding is the stator winding end 3 It is called.

Opposed to the end of the stator core 2, on the inner wall surface of the stator frame 11 are three reflector antennas 14, which are microwave band antennas with directivity.
15 (the remaining one is not shown) are arranged on the same circumference. The arrangement location is a position facing the winding closest to the output side of the stator winding end portion 3. Each of the reflector antennas 14 and 15 is attached via a bushing 19 that passes through the center of a metal lid 18 that closes the opening of a small case 17 attached to the stator frame 11.

FIG. 2 is an explanatory diagram showing the installation position of the reflector antenna with respect to a longitudinal sectional view of the fixed winding end 3. As shown in FIG. The stator winding 12 housed in the stator core 2 has a conductor 21
and an insulating layer 22 surrounding it, several tens of centimeters from the inside of the slot groove of the stator core 2 and the end of the stator core 2.
In m, a low resistance paint 23 is applied to the outside of the insulating layer 22. Further, a filler 24 is inserted between the two stator windings 12 to fill a gap. The reflector antenna 14 is arranged so that the electromagnetic waves radiated from the portion of the stator winding end 3 where the stator winding 12 protrudes from the stator core 2 are detected as direct waves. There are three reflector antennas 14 and 12 reflector antennas are arranged in the circumferential direction so that electromagnetic waves radiated from all the stator winding ends 3 can be detected.
It has directivity that can detect electromagnetic waves radiated from the stator winding end 3 in the 0 degree range. Note that two other reflector antennas are also installed in the same manner.

The reflector antennas 14 and 15 are connected to an abnormality detector 20 shown in the block diagram of FIG. 3 by a measurement cable 16 that sends detection signals S1 and S2. Other reflector antennas have similar configurations. The abnormality detector 20 includes an amplifier circuit 25, a filter circuit 26, a discharge detection calculation circuit 27, an abnormality determination circuit 28, and a display circuit 29.

Next, the operation of this embodiment will be explained. During operation of the generator 10, the conductor 21 in the stator winding 12
high voltage is generated. If an abnormality occurs in the stator winding 12 during operation, partial discharge occurs in the stator winding 12. Since the stator winding 12 has a form similar to a coaxial line due to the conductor 21, the low resistance paint 23, and the insulating layer 22 inside, high-frequency current propagates to the conductor 21 in the stator winding 12 due to the occurrence of partial discharge. At the same time, the transmitted electromagnetic wave propagates within the insulating layer 22. Electromagnetic waves of several tens of kHz to several tens of GHz are radiated into space at the stator winding end 3 where the low resistance paint 23 serving as the external conductor is interrupted. Several tens of MHz of this radiated electromagnetic wave
Components in the microwave band of up to several tens of GHz are detected by reflector antennas 14 and 15 provided so as to face the cross section of the portion where stator winding 12 protrudes from stator core 2.

Since the voltage generated in the stator winding 12 is highest at the part electrically close to the output terminal, abnormalities in the stator winding 12 due to electrical factors are more likely to occur near the output terminal. Since the antennas 14 and 15 are provided so that the stator winding end 3 closest to the output terminal is closest, the stator winding 12 has the highest probability of partial discharge.
Electromagnetic waves radiated from are detected with the highest sensitivity.

Furthermore, since components in the microwave band of several tens of MHz to several tens of GHz are detected among the radiated electromagnetic waves, signals based on individual discharges attenuate in a short time, and errors due to the overlap of multiple high-frequency signals occur. is small. Furthermore, the time resolution of detection can be significantly improved.

The detection signals S1 and S2 detected by the reflector antennas 14 and 15 are input to the amplifier circuit 25, and the amplified signals pass through the filter circuit 26, where only the frequency band with less noise is extracted, and the discharge detection calculation circuit 27 is input. The discharge detection calculation circuit 27 calculates the amount of discharged charge. The output of the discharge detection calculation circuit is input to the abnormality determination circuit 28 and compared with pre-registered data, abnormality is determined based on the amount of discharged charge and the frequency of occurrence, and the result is displayed on the display circuit 29.

In this embodiment, a plurality of reflector antennas are arranged on the same circumference, so there is no blind spot for electromagnetic waves, and the electromagnetic waves radiated from the stator winding end 3 closest to the partial discharge occurrence position are can be detected with high sensitivity with almost no attenuation. Furthermore, since the reflector antenna is attached to the stator frame 11 and a sufficient insulation distance can be provided from the high voltage stator winding 12,
Constant monitoring and abnormality detection can be performed even during operation without reducing the reliability of the rotating electrical machine.

In the embodiment, the abnormality detector 20 is installed outside the stator frame 11, but by downsizing part or all of the abnormality detector 20, it can be installed inside the stator frame 11. has the same effect.

Furthermore, in the embodiment, three reflector antennas were installed to detect the discharge occurring in all the stator windings 12, but if the number of reflector antennas is increased, the discharge can be detected with even higher sensitivity. Can be done.

Example 2 In Example 1, the discharges generated in all the stator windings 12 were detected by optimizing the directivity of the reflector antennas 14 and 15. However, even when a movable device 30 is attached to the mounting portions of the reflector antennas 14 and 15 as shown in FIG. 4, radiated electromagnetic waves in a wide range can be detected by changing the orientation of the reflector antennas 14 and 15 by the movable device 30. be able to. According to this configuration, it is possible to strengthen the directivity of the reflector antenna, and not only can the discharge generated in all the stator windings 12 be detected with higher sensitivity, but also the reflector antennas 14, 15
This has the effect of being able to identify the location of an abnormality by correlating the direction of the sensor with the detection results.

In the above embodiment, a reflector antenna was used as the microwave band antenna, but other antennas with directivity such as an aperture antenna, a microstrip array antenna, and a Yagi antenna may also be used. has the same effect.

Furthermore, although the above embodiments have been explained in the case of a generator, it goes without saying that the same effect can be achieved in rotating electric machines such as water turbine generators and induction motors.

[0027]

Effects of the Invention As described above, the abnormality detection device for a rotating electric machine of the present invention is capable of emitting radiation from the end of the stator winding near the end of the stator core due to partial discharge that occurs due to an abnormality in the stator winding. The electromagnetic waves generated by the electromagnetic waves are detected in a higher frequency band than before using a microwave band antenna with directivity installed on the inner wall of the stator frame. It has the effect of detecting partial discharges with high resolution and sensitivity, and constantly monitoring abnormalities in the stator windings. Further, since a sufficient insulation distance can be provided from the high-voltage stator winding to the antenna, the reliability of the rotating electrical machine will not be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an abnormality detection device for a rotating electric machine according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating the installation position of a reflector antenna according to the first embodiment of the present invention.

FIG. 3 is a block diagram of an abnormality detector according to Embodiment 1 of the present invention.

FIG. 4 is a cross-sectional configuration diagram showing an abnormality detection device for a rotating electrical machine according to a second embodiment of the present invention.

FIG. 5 is a perspective explanatory view showing a conventional partial discharge detection device for electrical equipment.

FIG. 6 is a block diagram of a conventional partial discharge detection device for electrical equipment.

FIG. 7 is a characteristic diagram of the signal level propagating in the winding for each frequency band.

[Explanation of symbols]

2 Stator core 10 Generator 11 Stator frame 12 Stator winding 14, 15 Reflector antenna 20 Abnormality detector

Claims (1)

[Claims] Claim 1: An abnormality detection device for a rotating electrical machine that detects an abnormality in the stator winding by detecting radiated electromagnetic waves based on partial discharge generated due to abnormality in the stator winding using an antenna, wherein the stator is accommodated. A plurality of microwave band antennas with directivity are installed in the circumferential direction at positions facing the cross section of the portion of the stator winding that protrudes outward from the stator core slot on the inner wall surface of the stator frame. An abnormality detection device for a rotating electric machine, characterized in that each of the devices is individually arranged.