JPH01236532A - Abnormality sensing device for gas insulated switching apparatus - Google Patents

Abstract

PURPOSE:To sense failure in power supplying by sensing specifier vibration generated when any failure has occurred under power supplying, comparing the frequency component which is even multiple of the supplied current, with the frequency component in the middle of the integer multiple, and judging that it is abnormal when the ratio obtained from the comparison exceeds a set value. CONSTITUTION:A vibration sensing means such as an acceleration sensor 1 and displacement sensor is installed on an apparatus whose abnormality shall be sensed, to measure the vibration waveforms, and the resultant is fed into a frequency analyzing means 3 such as spectrum analyzer and band-pass filter to take out the frequency component as even multiple of the supplied current frequency and also the frequency component approx. in the middle of two adjoining integer multiples, followed by comparison of the two and determination of their ratio. When this ratio exceeds the reference value set previously, it is judged that these is any abnormality in power supplying. This accomplishes high accuracy sensing of abnormality.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an abnormality detection device for gas-insulated switchgear equipment, and in particular, detects contact failures occurring in current-carrying parts with high reliability at a relatively early stage in the progress process leading to serious accidents. The present invention relates to an abnormality detection device for gas-insulated switchgear equipment that is suitable for detecting at high temperatures.

[Conventional technology]

In gas insulated switchgear, for example, the shutoff part is not closed properly.

Conventionally, when an abnormality in conduction occurs due to a defect in the spring that suppresses the contact, a defect in the bolt tightening of the conductor mounting part, etc., local overheating occurs due to an increase in contact resistance at a relatively early stage of the abnormality development process, and at the end of the process, local overheating occurs. It was thought that a minute spark discharge occurs between the deteriorated electrodes, and that the accompanying decomposition of SFe gas, vibrations, electromagnetic waves, electric pulses, etc. can be detected. Methods for detecting the above-mentioned phenomenon have been studied from the viewpoint of preventive maintenance to detect the above-mentioned energization abnormality before it develops into a serious accident such as a ground fault. For example, in the case of temperature detection devices,
6-68131, JP 55-154428, 2. JP 55-41165 for decomposed gas, JP 55-41165 for detecting electromagnetic waves, electric pulses, vibrations, etc. accompanying the generation of minute spark discharges. 55-117421, etc. are known.

(Problems to be Solved by the Invention) A problem common to the above-mentioned prior art is that although the sensitivity of each DI!L meter is at a sufficient level to capture the phenomenon, back noise at the substation site is Although it is possible to detect phenomena at the laboratory level because the phenomenon is far more accurate, there remains a problem in the accuracy of anomaly detection when it comes to practical use in the field. There has been a desire for a new anomaly detection method that can detect anomalies with high accuracy without being affected by noise.

In view of the above, it is an object of the present invention to provide means for detecting an abnormality with high accuracy by finding a unique phenomenon that occurs when one current is abnormal, and measuring this phenomenon.

[Means to solve the problem]

The above purpose is to install a vibration detection means such as an acceleration sensor or a displacement sensor on the equipment to be detected for an abnormality, measure the vibration waveform, and use a frequency analysis means such as a spectrum analyzer or a 41-band filter to detect an even number multiple of the frequency of one energized current. Cuts out a frequency component and a frequency component approximately in the middle of two adjacent integer multiple components.

This is done by comparing the two to determine the ratio, and when this ratio exceeds a preset reference value, it is determined that there is an abnormality in energization.

[Effect]

The results of a energization test using an abnormally energized contact.

It has been newly discovered that an audible sound is generated from the contact area, and that this can be detected as vibration if an acceleration sensor is installed in the container. The causes of vibration generation are thought to be as follows. As a model of contact parts, it is considered that even though they appear to be in surface contact, the true current-carrying part is actually a countless number of point contact parts of several micrometers to several tens of micrometers. At the abnormal current-carrying contact area, the total area of the above-mentioned true point contact area is insufficient for the current flowing due to insufficient contact force, etc., and the area near the true contact area becomes overheated due to excessive current concentration. There is. The time constant of temperature change near the true contact area is 10"-3 to 10-4
seconds, which is fast enough for changes in commercial frequency current. In other words, it is considered that the true temperature of the contact portion sufficiently follows the time change of the commercial frequency of one energizing current, and an equilibrium state is always established.

This means that heating is performed twice in correspondence with two maximum current values during one period of current supply, and cooling is performed twice in correspondence with two current zero points. Therefore, in the vicinity of the true contact portion, expansion and contraction are repeated at twice the frequency of the applied current, and as a result, the picture electrodes collide with each other at high speed, causing vibration. In fact, when this vibration waveform is actually measured and frequency analysis is attempted, it becomes a discrete spectrum whose main component is twice the frequency of the energized current. This indicates that the obtained vibration waveform is a repetitive waveform with a frequency twice the frequency of the applied current. However, perhaps due to the polarity effect, some frequency components that are the same as one current are included.

On the other hand, there are three types of back noise problems at substations: one caused by electromagnetic force caused by current, one-off noise caused by circuit breaker operation, and continuous noise caused by rain and wind. . The first electromagnetic force is generally 200 Hz
It has a vibration component below ~400 Hz. The vibration component associated with the above-mentioned energization abnormality usually exists in a frequency range higher than that, so it can be easily removed by passing it through a bypass filter. As for the second one-shot signal, the signal component is generally a continuous signal for several seconds or more, so it can be removed by software using a simple algorithm such as averaging processing on the time axis. Third
Rain, wind, etc. cause a problem because the signal level is relatively high and the signal is continuous. However, when actually measuring and analyzing the waveform, there is no regularity in the waveform, and the frequency components become a continuous spectrum.

The vibration waveform associated with the above-mentioned energization abnormality becomes a spectrum with discrete values, so this difference can be used to separate the two.
It is possible to improve the detection accuracy of energization abnormalities.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. This figure shows acceleration sensor 1. Preamplifier 29 Frequency analyzer neck 3
．． An energization abnormality detection device consisting of an arithmetic device 4 is connected to a gas circuit breaker 5.
An example of application is shown below. The gas cut-off booklet is a tank 7, which is a sealed container filled with an arc-extinguishing gas (generally SFe gas) 6 with excellent insulation performance, and a high potential part 10 consisting of a conductor 8, a cut-off part 9, etc., is connected by an insulating support tube 11. It has a configuration with edge support. When the power system is in operation, a current is introduced into the external conductor through 12', and if there is a poor contact somewhere in the high potential section 10 at this time, vibration will occur due to the above-mentioned mechanism. This vibration propagates to the tank 7 through the metal material that constitutes the high potential section 10 and the insulating support tube 11 that supports the high potential section 10. Therefore, vibration can be detected with high sensitivity by installing the acceleration sensor 1 near the insulating support cylinder 11 that is mechanically coupled to a high potential portion. Naturally, it is possible to achieve even higher sensitivity by installing the acceleration sensor 1 in the high potential part 10 and insulating it with an optical fiber or the like to transmit the signal, but in order to prioritize the reliability of the circuit breaker, the sensors are placed outside the tongue. The current mainstream preventive maintenance technology is an external diagnostic method installed at the site. There are several ways to install the acceleration sensor l, such as bolting, adhesives, magnets, etc., but it is desirable to install it as firmly as possible based on the measurement principle. For the purpose of the present invention, semi-permanent installation is often required, and bolt fastening is preferable. It is preferable to provide a protective cover on the mounting part of the acceleration sensor 1 for the purpose of protecting it and reducing external noise caused by wind and rain, but it is not shown here. If a piezoelectric sensor is used as the acceleration sensor 1, for example, a preamplifier 2 such as a charge amplifier is required to amplify the amount of generated charge. When the acceleration sensor 1 with a built-in amplifier is used, the drive power source is used in place of the preamplifier. Preamplifier 2
The output is input to a frequency analyzer 3, and is input to an arithmetic unit 4 such as a personal computer in the form of vibration components separated for each frequency. Generally, in a preventive maintenance system for substation equipment, many items of many equipment are to be detected, so some kind of computing device is applied to integrate and control these signals.
The functions of the arithmetic bag@4 in the present invention can also be integrated into this. The functions of the frequency analyzer 3 can also be handled by the arithmetic unit 4 by incorporating dedicated software.
By providing the dedicated bag W3, it is possible to increase the speed of calculation, so the configuration shown in the figure is used here.

3 and 4 show the output waveforms of the frequency analyzer 3.

The horizontal axis represents the frequency J, and the vertical axis represents the logarithm of the vibration intensity G. Waveform a in FIG. 3 shows a state in which external noise is relatively small during normal energization. In the frequency range below 2008 Z, there are components such as induction due to the commercial frequency current and electromagnetic force, making it unsuitable for abnormality detection, so the figure shows the frequency range above this. Waveform A in FIG. 3 is a case where there is an influence of external noise such as wind and rain, and is shifted upward with respect to waveform a. Therefore, it is dangerous to set a certain value as a criterion for detecting an abnormality in energization and to determine an abnormality when the signal level exceeds that value, as it may lead to malfunction when the external noise level becomes large. The waveform shown in FIG. 4 is the waveform when there is an abnormality in energization. As shown in the figure, there are large vibration components at frequencies that are even multiples of the energizing current frequency, and relatively small frequency components at frequencies that are odd multiples. There is a valley between them and there are few vibration components. When external noise such as wind and rain is superimposed on the IIM abnormal waveform shown in Figure 4,
The waveform in the figure is similar to an upwardly shifted waveform. Therefore, as a criterion for detecting an energization abnormality, the value should be expressed as how many times the even number multiple component P of the energization current frequency is compared to the value between adjacent integral number multiple components. The specific value should be 2 to 10 times or more, and as a means to improve detection reliability, multiple peaks should be similarly verified and AND
Alternatively, it may be better to take OR.

FIG. 2 shows an inexpensive configuration that can be used in cases where there are many detection points, such as in a gas-insulated switchyard. As in the previous example, an acceleration sensor 1 is installed on the outer wall of the tank 7, and after being passed through a preamplifier 2, it is processed by a narrowband bandpass filter 13, 13'. The center frequencies of the bandpass filters 13, 13' are set at P and L in FIG. Even more simply, it is also possible to configure the bandpass filters 13, 13' with tuned circuits.

〔Effect of the invention〕

According to the present invention, a sensor that detects vibrations is used to detect specific vibrations that occur during abnormal energization, and the frequency components of even multiples of the energized current are compared with the frequency components between the integer multiples, and the ratio is determined. By following an abnormality detection algorithm that determines an abnormality when the value exceeds a set value, it is possible to detect normal energization with high accuracy even in the presence of external noise.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the overall configuration of the present invention, FIG. 2 is a schematic diagram showing different embodiments, and FIGS. 3 and 4 are diagrams showing the principle of the present invention. 1... Acceleration sensor, 3... Frequency analyzer, 4.
Arithmetic device, 5... Gas circuit breaker, 6... Insulating gas,
7.Tank, 10..P high potential part, a, b, Q..vibration waveform, P..even frequency component, L..intermediate frequency component of adjacent integer multiple frequency.

Claims (1)

[Claims] 1. Consists of an airtight container filled with an insulating gas and a high potential part forming a current carrying path insulated and supported in the airtight container, and detects vibrations generated from poor contact parts when current is applied. In the case where a sensor is installed, the frequency component of the vibration waveform measured by the sensor that is an even number multiple of the frequency of the energized current is compared with the intermediate frequency component of two adjacent integral multiples of the frequency of the energized current, and the ratio is determined. An abnormality detection device for gas-insulated switchgear equipment, characterized in that an abnormality is determined when a preset determination reference value is exceeded. 2. An abnormality detection device for gas-insulated switchgear equipment according to claim 1, characterized in that the determination reference value is set to twice or more.