JPH04331382A - Insulation diagnostic apparatus for gas insulated device - Google Patents

Abstract

PURPOSE:To obtain an insulation diagnostic apparatus for a gas insulated device possible to detect an occurrence point of internal abnormality by the measurement to use one acceleration sensor. CONSTITUTION:An output of an acceleration sensor P is passed through a plurality of band-pass filters 41, 42, 43 of different pass frequency bands, and a time lag due to the pass frequency bands to arrive at the acceleration sensor P is detected by an operation circuit 7. The position of the internal abnormality can be detected by arranging only one acceleration sensor P, because the position of the internal abnormality of an internal discharge, etc., is detected by the operation circuit 7, utilizing that the propagation velocity of a wave to propagate a tank wall 1a of a metal tank is different by an oscillation frequency.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation diagnostic device for detecting the presence or absence of an internal abnormality in a gas insulating device, and more particularly to a device for performing insulation diagnosis through measurement of vibration and acceleration.

0002

[Prior Art] For example, conventional insulation that measures vibration and acceleration as shown in the Institute of Electrical Engineers of Japan/Insulating Materials/High Voltage Joint Study Group Material EIM-89-5 HV-89-5 "Insulation Diagnosis of Gas Insulated Switchgear" The diagnostic device is shown in FIG.

In FIG. 5 showing a conventional example, the center conductor (
2) is located in the center of the tank (1) which has a gas space such as SF6 gas. To detect vibrations in the tank wall (1a),
An acceleration sensor (P) is attached to the tank wall (1a) using grease (1b). The output of the acceleration sensor (P) is amplified by the amplification amplifier (3), and the noise component accompanying the electromagnetic vibration of the tank is filtered through a high-pass filter (4).
after being removed by the AD converter (5).

The synchronizing signal generator (6) is a circuit for generating a signal synchronized with the power supply cycle in order to distinguish between a signal such as a partial discharge synchronized with the power supply cycle and random external noise. The AD converter (5) performs absolute value addition processing in synchronization with the power cycle, and the arithmetic circuit (7) calculates an averaged waveform, which is displayed on the display circuit (8).

[0005] When an internal abnormality such as a partial discharge occurs inside the gas insulated switchgear, the tank receives an impact proportional to the discharge energy, causing vibration. This vibration is caused by the tank wall (1
a) Propagate. This vibration is detected by an acceleration sensor (P), amplified by an amplifier (3), and a high-pass filter (
After being removed in step 4), the AD converter (5) performs absolute value addition processing synchronized with the power cycle. AD converter (5
) is input to an arithmetic circuit (7) to calculate an averaged waveform, which is displayed by a display circuit (8).

[0006]

[Problems to be Solved by the Invention] Conventional devices that perform absolute diagnosis through measurement of vibration and acceleration are configured as described above, and in order to detect the point of occurrence of internal abnormality from the measurement output, an acceleration sensor is required. There was a problem in that it required multiple measurements by changing the mounting position of (P) or simultaneous measurements using multiple sensors.

[0007] The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide an insulation diagnostic device for a gas insulated device, which has an improved and simple configuration and is capable of detecting the point of occurrence of an internal abnormality. .

[0008]

[Means for Solving the Problems] An insulation diagnostic device for a gas insulating device according to the first aspect of the invention includes an acceleration sensor for detecting vibrations of a tank wall of a gas insulating device, and a pass frequency band that receives the output of the acceleration sensor as input. The apparatus includes a plurality of band-pass filters having different values, and an arithmetic circuit that receives the outputs of the band-pass filters and detects a propagation time difference depending on a pass frequency band from when vibration occurs until it reaches the acceleration sensor. An insulation diagnostic device for a gas insulating device according to a second aspect of the invention includes an acceleration sensor that detects vibrations of a tank wall of the gas insulating device, a bandpass filter with a variable pass frequency band that receives the output of the acceleration sensor as an input;
An arithmetic circuit is provided that inputs the outputs of the bandpass filters in different frequency bands and detects a propagation time difference depending on the pass frequency band from when vibration occurs until it reaches the acceleration sensor.

[0009]

[Operation] In the insulation diagnostic device according to the present invention, the output of the acceleration sensor that detects the vibration of the tank wall is divided into a plurality of electrical signals by a plurality of bandpass filters with different passing frequency bands or a bandpass filter that changes the passing frequency band. It will be done. Thereby, by utilizing the fact that the propagation speed of the vibration wave propagating through the tank wall differs depending on the vibration frequency, the calculation circuit performs calculations to detect the position of the internal discharge.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of an insulation diagnostic apparatus according to the present invention.

<Configuration> In FIG. 1, there is a center conductor (2) in the center of a tank (1) having a space for gas such as SF6 gas, and an acceleration sensor (P) is installed to detect vibrations of the tank wall (1a). Grease (1b) is used to seal the tank wall (1a).
) is attached. A single acceleration sensor (P), which detects vibrations in the tank wall (1a), is attached to one end of the tank, and its output is amplified by an amplification amplifier (3). The output of the amplification amplifier (3) is a first filter (41) which is a band pass filter with a pass frequency band of 3 to 6 KHz, for example, and a second filter which is a band pass filter with a pass frequency band of 10 to 20 KHZ, for example. (42). The outputs of the first filter (41) and the second filter (42) are input to the AD converter (5) via the changeover switch (9).

The synchronization signal generator (6) generates a signal synchronized with the power supply cycle in order to distinguish detected components based on partial discharges etc. which are synchronized with the power supply cycle and random external nozzles. The AD converter (5) performs absolute value addition processing in synchronization with the power cycle. Is the selector switch (9) connected to the first filter (41) or the second filter (42)?
) is input to the arithmetic circuit (7).

[0013] When an internal abnormality such as a partial discharge occurs inside the gas insulated switchgear, the tank (1) receives an impact proportional to the discharge energy and vibrates. This vibration propagates through the tank wall (1a). The output of the acceleration sensor (P) that detects the vibration of the tank wall (1a) is amplified by the amplification amplifier (3), and the random noise components accompanying electromagnetic vibration of the tank (1) are filtered through the first filter (41). After being removed by the second filter (42), the signal is input to the AD converter (5). The AD converter (5) performs absolute value addition processing synchronized with the power supply cycle, and these first filters (41)
The AD-converted data is passed through the second filter (42) and input to the arithmetic circuit (7).

FIG. 2 schematically shows an example of a vibration waveform generated on the tank wall (1a). FIG. 2(a) shows the output of the first filter (41), and FIG. 2(b) shows the output of the second filter (42). In these figures, t0 indicates the point at which the partial discharge occurs, and T1 and T2 indicate the frequency oscillation in each pass frequency band after the partial discharge occurs at the acceleration sensor (P).
It shows the time it takes to reach .

The times T1 and T2 from the time t0 when partial discharge occurs in the bandpass filter of each pass frequency band until the vibration reaches the acceleration sensor (P) are determined by the calculation circuit (
7) is temporarily stored.

FIGS. 2(c) and 2(d) show the reference time tr
The outputs of the first filter (41) and the second filter (42) are shown when there is a time T0 from (for example, the zero-crossing point of the AC voltage) to the time t0 when partial discharge occurs.

FIG. 3 is a graph showing the relationship between the frequency and propagation speed of vibration waves transmitted through the tank (1) of the gas insulated switchgear. As seen in the curve of FIG. 3, in a relatively low frequency region, the vibration propagation velocity increases approximately in proportion to the square root of the frequency.

<Operation> The operation of one embodiment of the above configuration will be explained. If an internal abnormality such as partial discharge occurs inside the gas insulated switchgear, the tank (1
) propagates through the tank wall (1a) at different speeds as shown in Figure 3 depending on the frequency. Let the distance from the current discharge occurrence point t0 to the acceleration sensor (P) be L, and each output after passing through the first filter (41) and the second filter (42) reaches the acceleration sensor (P) from the internal discharge occurrence point t0. If the times are T1 and T2, these two times T1
and T2 are temporarily stored in the memory within the arithmetic circuit (7). Therefore, the first filter (41) or the second filter
Assuming that the frequency of the filter (42) is f1 or f2 and the propagation velocity is v1 or v2, the distance L from the internal discharge generation point to the acceleration sensor (P) is determined as follows. L = v1・T1 = v2・T2
------ (1). If (T1-T2) is expressed as ΔT, ΔT = T1-T2 = L (1/v1 - 1
/v2) ------- (2). From formula (2), L = v1v2/(v2-v1) · ΔT. In other words, the arithmetic circuit (7) calculates the time difference ΔT when vibrations due to internal discharge reach the acceleration sensor (P), so the distance L from the acceleration sensor (P) to the point of occurrence of internal abnormality such as internal discharge can be calculated. .

As shown in FIGS. 2(c) and 2(d), even if there is a time T0 from the reference time to the occurrence of partial discharge, the first filter (41) and the second filter (42)
) The distance L from the point of occurrence of partial discharge to the acceleration sensor (P) is calculated by measuring the time difference ΔT between the output waveforms.

FIG. 4 shows a variable bandpass filter (43) in which the bandpass filter can change the passing frequency bandwidth.
Another example is shown below. Variable bandpass filter (
Information on the passing frequency bandwidth of 43) is input to the arithmetic circuit (7). Partial discharge in gas-insulated switchgear is synchronized with the power cycle. Therefore, the output of the acceleration sensor (P) is synchronized with the power supply cycle, and even if the time for the output of the acceleration sensor (P) to pass through the variable filter (43) is different, the output from the acceleration sensor (P) is transferred from the point of occurrence of internal discharge to the acceleration sensor (P). It is possible to temporarily store the arrival time by the arithmetic circuit (7) and calculate the arrival time difference ΔT depending on the passing frequency.

Information on the passing frequency of the variable bandpass filter (43) is input to the arithmetic circuit (7), so by calculating the arrival time difference ΔT depending on the passing frequency, from the point of occurrence of partial discharge to the acceleration sensor (P). distance L
is found.

[0022]

Effects of the Invention: The output of the acceleration sensor (P) that detects the vibration of the tank wall (1a) is processed by a plurality of bandpass filters with different passing frequency bands or a single bandpass filter that changes.
Divided into multiple electrical signals, the tank wall of the metal tank (1a
) The arithmetic circuit (7) detects the position of internal abnormalities such as internal discharge by utilizing the fact that the propagation speed of waves propagating in the The location of the abnormality can be detected.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of an embodiment of an insulation diagnostic device for a gas-insulated switchgear according to the present invention.

FIG. 2 is a diagram of vibration waveforms generated on the tank wall (1a) after passing through filters with different pass frequency bands.

FIG. 3 is a graph showing the relationship between the frequency and speed of waves propagating through the tank wall (1a) of the gas-insulated switchgear.

FIG. 4 is a circuit block diagram of another embodiment of the insulation diagnostic device for gas-insulated switchgear according to the present invention.

FIG. 5 is a circuit block diagram of a conventional insulation diagnostic device for gas-insulated switchgear.

[Explanation of symbols]

1a Tank wall 7 Arithmetic circuit 41 First filter 42 Second filter 43 Variable bandpass filter P Acceleration sensor

Claims (2)

[Claims] 1. An acceleration sensor that detects vibrations of a tank wall of a gas insulating device; a plurality of bandpass filters having different pass frequency bands that receive the output of the acceleration sensor as input; each output of the bandpass filter is inputted; an arithmetic circuit that detects a propagation time difference depending on a pass frequency band from when vibration occurs until it reaches the acceleration sensor;
An insulation diagnostic device for gas insulation equipment, comprising: 2. An acceleration sensor that detects vibrations of a tank wall of a gas insulating device; a bandpass filter with a variable pass frequency band that receives the output of the acceleration sensor as an input;
Insulation diagnosis of a gas insulated device, comprising: an arithmetic circuit that inputs the outputs of the bandpass filters in different frequency bands and detects a propagation time difference depending on the pass frequency band from when vibration occurs until it reaches the acceleration sensor. Device.