JPH04296675A - Method to detect abnormality of rotary electric machine - Google Patents

Abstract

PURPOSE:To provide a method to detect abnormality of a rotary electric machine, the position and degree of the abnormality, highly accurately by detecting the generation position of the electrical discharge along with the abnormality in the rotary electric machine. CONSTITUTION:An electrical discharge detecting element 8 made of an electric conductor is arranged between both stator coils 4 in all the stator slots 7 of a rotary electric machine 1. By specifying an electrical discharge generation position by the component of 1MHz or more, in which the damp of a high frequency signal in the stator coils based on the electrical discharge along with the abnormality of the stator coil 4, which is detected, is remarkable, electrical discharge properties are measured to detect the position and the degree of the abnormality.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality in a rotating electrical machine that can accurately detect and monitor abnormalities caused by insulation deterioration in 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, since high reliability is particularly required for such rotating electric machines, maintenance and inspection must be carried out reliably.
It is necessary to prevent sudden accidents such as insulation 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. 7 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. 8 is a block diagram thereof. In Figure 7,
30 is a stator, 3 is a stator core, 31 is a stator winding end, and 32 is an antenna wire for detecting partial discharge. The antenna wire 32 captures the electromagnetic waves generated by the partial discharge pulse current, and the output from the antenna wire 32 is guided to the detection circuit 34 via the lead wire 33 as shown in FIG. It passes through a high-pass filter 35 to remove the normal voltage frequency, and then a partial discharge counter 36
It is used to measure partial discharges.

[0008]

In a device having a winding, such as a rotating electric machine, a high frequency signal propagating through the stator winding due to discharge is significantly attenuated as the signal propagates due to the inductance of the stator winding. The degree of this attenuation is more pronounced in higher frequency bands. For this reason, in conventional partial discharge detection devices,
When trying to detect an abnormality in the entire device, a signal in a frequency band of about 500 kHz or less, which has relatively low attenuation, is detected. Furthermore, due to the complicated winding shapes of rotating electric machines, the propagation characteristics of high-frequency currents are not clearly understood.
With conventional methods, it has been difficult to identify the location where discharge occurs. Therefore, in the conventional partial discharge detection device, it is difficult to quantitatively measure the discharge in the entire device due to the attenuation of the high frequency signal.

The present invention has been made to solve the above-mentioned problems, and provides a method for detecting an abnormality in a rotating electric machine that can accurately detect the position and degree of an abnormality by detecting the position where electric discharge occurs. The purpose is to

0010

[Means for Solving the Problems] The abnormality detection method for a rotating electric machine of the present invention is to electrostatically or inductively couple a high-frequency signal based on a partial discharge generated due to an abnormality that propagates through a stator winding. A plurality of discharge detection elements made of conductors are provided inside a plurality of stator slots of a rotating electric machine, and a high frequency signal based on the discharge outputted by the discharge detection element is detected, and a stator winding of the detected high frequency signal is detected. Identifying the discharge occurrence position using a component of 1 MHz or more that is significantly attenuated in the line and measuring the discharge characteristics at each stator slot,
Compare the above measured discharge characteristics with their changes over time and discharge characteristics during abnormal conditions, and based on the judgment criteria.

[0011] Furthermore, the detected high frequency signal is 100kHz.
By comparing at least one of the detected waveform, the difference in detection time, and the frequency characteristic of the component of z or more between each discharge detection element, the discharge occurrence position is identified, and the discharge characteristic at each stator slot is measured. This is how it was done.

0012

[Operation] The operation of the abnormality detection method for a rotating electric machine according to the present invention will be explained. A high frequency signal induced in the stator winding due to a discharge caused by an abnormality in the stator winding of a rotating electric machine is electrostatically or inductively detected by a discharge detection element disposed inside each stator slot. The discharge characteristics for each discharge occurrence position are determined from the components of 1 MHz or more of the detected high-frequency signal. Now, in this high frequency band of 1 MHz or more, attenuation in the stator winding is extremely significant, and high frequency signals caused by individual discharges are detected only by the nearest discharge detection element. This makes the location where the discharge occurred obvious, and the location can be easily identified. Therefore, discharge characteristics can be measured with high accuracy. Furthermore, it is possible to obtain changes over time in the discharge characteristics from the determined discharge characteristics and the recorded past discharge characteristics. Based on this result and the accumulated characteristics of past abnormalities, the location where the current abnormality is occurring and the degree of the abnormality can be determined.

[0013] Also, using the components of 100 kHz or higher, which have a slightly less attenuation of the high-frequency signal in the stator winding of the detection result of the high-frequency signal from each discharge detection element, any one of the detected waveform, the difference in detection time, and the frequency characteristic is determined. By comparing three or more discharge detection elements, it is possible to specify the position where the discharge has occurred. To identify the position, characteristics such as attenuation and distortion of the detected waveform accompanying the propagation of high-frequency pulses, a delay in detection time, and a shift of the frequency spectrum to the lower frequency region are used. Based on this, the discharge characteristics for each discharge occurrence position are calculated. In this case, a wide range of high-frequency signals are detected, starting from 100kHz or higher, where the signal attenuation is slightly less, and it is possible to detect high-frequency signals generated not only in the stator slot where the discharge detection element is installed, but also in adjacent slots. So,
The number of discharge detection elements can be reduced.

[0014]

[Example] Example 1. Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 to 3. FIG. 1 is a cross-sectional configuration diagram showing the structure of an abnormality detection device for a rotating electrical machine according to Embodiment 1 of the present invention, and FIG. 2 shows a cross section of the stator core end and stator winding in FIG. 1, and shows the installation position of the discharge detection element. FIG. 3 is a block diagram showing the abnormality detector of FIG. 1. The rotating electric machine 1 is composed of a stator and a rotor 5, each of which includes a stator frame 2, a stator core 3, a stator winding 4, and the like. A stator core 3 is fixed to the stator frame 2, and a predetermined number of stator slots 6 are provided on the inner peripheral surface of the core at equal intervals in the axial direction, and two upper and lower stator windings 4 are provided in this portion. is housed and fixed by a wedge 7. Reference numeral 8 denotes a discharge detection element made of a conductor, and is installed between the upper and lower two stator windings 4 inside all the stator slots 6. The discharge detection element 8 is connected to a shielded lead wire 9 and is insulated from other conductors. The lead wire 9 is connected to the small case 1 attached to the stator frame 2.
It is connected to the abnormality detector 10 via an airtight terminal 13 that passes through the center of a metal lid 12 that closes the opening of the metal lid 12 . All leads 9 corresponding to each stator slot 6 have equal length.

The abnormality detector 10 shown in FIG.
a detection circuit 14 connected in series with the stator winding 4, a filter circuit 15 that separates a frequency band of 1 MHz or more that is significantly attenuated in the stator winding 4, a discharge measurement circuit 17 that measures the discharge characteristics in each stator slot 6, A recording device 18 that records measured discharge characteristics, an abnormality characteristic recording device 19 that records discharge characteristics during past abnormalities, and an abnormality determination that determines an abnormality based on the outputs from the recording device 18 and the abnormality characteristic recording device 19. It is comprised of a circuit 20 and a determination display device 21 that displays the results determined by the abnormality determination circuit 20.

Next, the operation of this embodiment will be explained. A high voltage is generated in the stator winding 4 while the rotating electric machine is operating. Therefore, when an abnormality occurs in the insulation of the rotating electrical machine due to insulation deterioration of the stator winding 4, discharge occurs and a pulse-like high frequency signal propagates to the stator winding 3. A discharge detection element 8 disposed between the upper and lower stator windings 4 inside the stator slot 6 is electrostatically coupled to the stator winding 3, and detects high frequency waves propagating to the stator winding 3. A high frequency voltage is induced in the discharge detection element 8 by the signal. This high frequency voltage propagates through the lead wire 9 and is input to the detection circuit 14, where the high frequency voltage is detected. The output of the detection circuit 14 is connected to a filter circuit 15 in order to extract components in a frequency band suitable for accurately and easily specifying the discharge occurrence position and accurately calculating discharge characteristics from this high-frequency voltage.

This high-frequency voltage includes components that are not caused by the above-mentioned discharge, such as electromagnetic noise generated inside the rotating electrical machine, electromagnetic noise that enters from other equipment connected to this rotating electrical machine, and electromagnetic waves that enter from the outside. include. Furthermore, although the high-frequency voltage caused by the above-mentioned discharge includes a wide band frequency component of 1 kHz to 1 GHz, in order to identify the stator slot 6 where the discharge has occurred, it is necessary to use a discharge detector installed in the stator slot 6. element 8 in another stator slot 6
It is preferable not to detect high frequency signals generated inside the device. Therefore, it is preferable to use a frequency band of the filter circuit 15 that is 1 MHz or more, where high-frequency signals are significantly attenuated inside the stator winding 4, and has little noise. In particular, a band up to 1 GHz where the signal strength due to discharge is strong is considered desirable. Furthermore, since the propagation characteristics of high-frequency signals in the stator windings depend on the shape of the stator windings, it is preferable to determine the frequency band for each device. This generally applies to the frequency band of the amplifier circuit used inside the discharge measuring circuit 17, and even if the filter circuit 15 and this amplifier circuit are configured to have the above band, the same result will occur. It becomes an action.

The output of the filter circuit 15 is transmitted to the discharge measuring circuit 1.
7, and discharge characteristics such as the amount of discharged charge in each stator slot 6, generation phase with respect to commercial voltage, generation frequency, and spectrum are measured. The discharge characteristics determined by the discharge measurement circuit 17 are recorded by the recording device 18, and are outputted to the abnormality determination circuit 20 as needed to determine changes over time in the discharge characteristics. The abnormality determination circuit 20 detects the occurrence of an abnormality based on the discharge characteristics obtained from the rotating electric machine being monitored and their changes over time, based on the discharge characteristics during past abnormal times and the abnormality determination criteria recorded in the abnormal characteristics recording device 19. The stator slot 6 that has been damaged and the degree of abnormality are determined. This determination result is output to the determination display device 21 and displayed.

As described above, by providing discharge detection elements in all stator slots and using a frequency band with less noise above 1 MHz, where the detected high-frequency signal is significantly attenuated inside the stator winding 4. , the discharge occurrence position (stator slot) can be easily and accurately specified, and the discharge characteristics can be measured with high precision. Thus, the position and extent of the abnormality can be detected and an abnormality judgment can be made.

Example 2. In the above embodiment, the detection circuit 1 is provided for each stator slot 6.
4. We installed a filter circuit 15 and a discharge characteristic measurement circuit 17, and simultaneously measured the high-frequency voltages in multiple stator slots 6 to determine the location where each discharge phenomenon occurred. Compared to the discharge phenomenon, it only takes a long time to perform the process, so Example 2 in FIG.
As shown in the block diagram of the abnormality detector related to Child slots can be detected and there is a similar anomaly detection function.

Example 3. In the above embodiment, in order to identify the stator slot where a discharge has occurred, the high frequency signal is attenuated in the stator winding so that the discharge is not detected by any discharge detection element other than the discharge detection element of this stator slot. However, as shown in the block diagram of the abnormality detector according to the third embodiment in FIG. A comparison circuit 16 may be provided to compare peak voltages of high-frequency voltage pulses between a plurality of discharge detection elements using a frequency band of 2 to specify the position where a discharge pulse is generated. As a result, the discharge characteristics for each discharge occurrence position can be determined with high accuracy, and the same effects as in the above embodiment can be achieved.

Note that in the frequency band of this embodiment, the attenuation of the high frequency signal is rather small and the signal propagates across several stator slots, so it is not necessary to install discharge detection elements in all stator slots. The number of discharge detection elements to be installed can be reduced, and the configuration of the device can be simplified. for example,
If the low frequency band of about 100 kHz is used to detect the location of discharge occurrence, if the discharge detection element is installed at an electrically symmetrical position of about 30% of all stator slots, it will be possible to detect the discharge of the entire device, and the same effect can be achieved. be.

Further, in this embodiment, the peak voltage of the high frequency voltage is used to specify the position of discharge occurrence, but the comparator circuit 16 By measuring the difference in the detection time of the signal between the discharge detection elements, the location of the discharge can be identified.
The same effect as this embodiment is achieved. Further, by simultaneously specifying the discharge occurrence position based on the peak voltage of the high frequency signal and the discharge occurrence position based on the difference in detection time, it is possible to accurately specify the discharge occurrence position.

Example 4. In Example 3, the peak voltage of the high-frequency voltage and the difference in detection time were used to identify the position of discharge occurrence, but Example 4 in FIG.
As shown in the block diagram of the abnormality detector related to
3. A low-band filter circuit 24 is provided, and by using the difference in the attenuation characteristics of the high-frequency voltage pulse in the stator winding between the two bands, the ratio of the peak voltage in these two bands can be calculated between each stator slot. A similar effect can be expected by comparing. This embodiment utilizes the characteristic that the frequency spectrum shifts to a lower frequency region as a high frequency signal propagates through the stator winding.

In the above embodiment, the discharge detection element 8
is electrostatically coupled to the stator winding 4, but the discharge detection element 8 is configured to be inductively coupled to the stator winding 4,
For example, the same effect can be obtained even if the detection circuit 14 measures the high frequency current flowing through the coil-shaped discharge detection element.

Furthermore, in the above embodiment, the abnormality detector 1
0 was installed outside the stator slot 6, but the detection circuit 1
4. A similar effect can be obtained even if a part of the abnormality detector 10 such as the filter circuit 15 is integrated in a small size and installed inside the stator slot 6.

Further, in the above embodiment, the discharge detection element 8 was installed between the upper and lower stator windings 4 inside the stator slot 6, but between the wedge 7 and the upper part of the stator winding 4, a fixed At a position adjacent to the stator winding 4 inside the stator slot 6, such as between the bottom of the child slot 6 and the lower part of the stator winding 4, or between the side surface of the stator winding 4 and the stator slot 6. A similar function can be expected even if the discharge detection element 8 is installed.

In addition, in the first and second embodiments, the case where the discharge detection elements 8 are installed in all the stator slots 6 has been explained, but the number of discharge detection elements 8 is small near the neutral point where almost no discharge occurs during operation. A similar effect can be obtained by reducing the number of discharge detection elements 8 in the same stator slot 6.
By arranging this, it becomes possible to specify the location of discharge occurrence with even higher accuracy.

[0029]

As described above, the abnormality detection method for a rotating electrical machine according to the present invention includes providing a plurality of discharge detection elements inside a plurality of stator slots of the rotating electrical machine, and detecting the stator windings output by the discharge detection elements. Detects high-frequency signals based on discharges associated with line abnormalities, and detects components of 1 MHz or higher that are significantly attenuated in the stator windings, or 100 kHz or higher components of the detected high-frequency signals that are significantly attenuated in the stator windings. By comparing at least one of the detected waveform, the difference in detection time, and the frequency characteristic between each discharge detection element, the discharge occurrence position is identified and the discharge characteristic is measured, and the measured discharge characteristic and its Abnormality is determined based on changes over time and discharge characteristics during abnormal conditions, and has the effect of accurately detecting the position and degree of abnormality.

[Brief explanation of drawings]

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

FIG. 2 is a diagram illustrating the installation position of a discharge detection element according to Example 1 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 block diagram of an abnormality detector according to a second embodiment of the present invention.

FIG. 5 is a block diagram of an abnormality detector according to a third embodiment of the present invention.

FIG. 6 is a block diagram of an abnormality detector according to a fourth embodiment of the present invention.

FIG. 7 is a perspective explanatory view showing a conventional partial discharge detection device for electrical equipment.

FIG. 8 is a block diagram of a conventional partial discharge detection device for electrical equipment.

[Explanation of symbols]

1 Rotating electrical machine 3 Stator core 4 Stator winding 6 Stator slot 8 Discharge detection element 10 Abnormality detector 14 Detection circuit 15 Filter circuit 16 Comparison circuit 17 Discharge measurement circuit 18 Recording device 19 Abnormal characteristics recording device 20 Abnormality determination circuit

Claims (2)

[Claims] 1. A plurality of discharge detection elements made of conductors are provided inside a plurality of stator slots of a rotating electrical machine to detect partial discharges occurring due to an abnormality in the stator windings, and the discharge detection elements output from the discharge detection elements are A high-frequency signal based on discharge is detected, and the discharge occurrence position is identified by the component of 1 MHz or more that is significantly attenuated in the stator windings of the detected high-frequency signal, and the discharge characteristics at each stator slot are measured. death,
A method for detecting an abnormality in a rotating electric machine, in which an abnormality is determined from the measured discharge characteristics, their changes over time, and the discharge characteristics at abnormal times. [Claim 2] 100kHz of the detected high frequency signal
Claim 1, wherein the discharge occurrence position is identified and the discharge characteristics are measured by comparing at least one of the detected waveform, the difference in detection time, and the frequency characteristics of the above components between each discharge detection element. A method for detecting abnormalities in rotating electric machines.