JPS6182406A - Monitoring device of oil-filled electric apparatus - Google Patents

Abstract

PURPOSE:To monitor with high reliability by detecting a partial discharge from both signals of a current pulse upon partial discharging and a partial discharge sound, and detecting the special low frequency component of the partial sound corresponding to the detected values of an exciting voltage and a negative charge current. CONSTITUTION:If a partial discharge occurs in an oil-filled electric apparatus 10, detecting impedances 13, 14 detect current pulses, acoustic sensors 16a, 16b simultaneously detects a partial discharge sound from the propagation time delay in a tank 10a, and inputs to a partial discharge monitor 15. Whether it is partial discharge or an external noise is discriminated. In case of the partial discharge, an alarm output is generated, and the partial discharge place is obtained by calculating. In 1kHz or lower range, the sensitivity is constant irrespective of the frequency, and the frequency in the level discrimination does not becomes trouble. The strength deterioration of a solid insulator can be also detected by detecting the low frequency component of 1kHz of lower of partial discharge sound, and a mechanical malfunction can be also detected in addition to an electric malfunction.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention monitors electrical abnormalities such as partial discharge that occur inside oil-filled electrical appliances and mechanical abnormalities due to strength deterioration of solid insulators, thereby preventing accidents. The present invention relates to a monitoring device for oil-filled appliances to prevent this.

[Technical background of the invention and its problems]

Oil-filled electrical equipment used in power systems, such as oil-filled transformers, has recently become larger in capacity and ultra-high voltage, and has become an important device in terms of power supply. If such an oil-filled appliance were to cause an accident for some reason, the impact would be enormous, such as the power supply being cut off and the accident spreading to other equipment, and could even have a negative impact on society.

Therefore, monitoring is required to detect signs of accidents and prevent them from occurring.

Conventionally, such monitoring devices have been used to detect partial discharges that cause insulation breakdown accidents in oil-filled electrical appliances. There are generally two types of monitoring means: electrical means and acoustic means.
There are two means. As an electrical means, there is a means to detect the current pulse generated in the electric circuit when a partial discharge occurs inside the oil-filled appliance, and as an acoustic means, there is also a means to detect the partial discharge sound on the outer wall of the tank of the oil-filled appliance. Tori (t ff
? , there is a means for detecting with an acoustic sensor such as a knee microphone. However, electrical means tend to have the disadvantage of being susceptible to induced noise from the system to which the oil-filled appliance is connected, while acoustic means can also malfunction due to noise such as the sound of rain or noise when foreign objects hit the tank. There is a drawback.

For this reason, in practice, the above-mentioned electrical and acoustic means are used together,
We aim to improve the reliability of goldfish combs that can prevent malfunctions due to noise.

However, if the materials such as solid insulators that make up oil-filled equipment deteriorate due to long-term operation of oil-filled equipment, the deterioration of mechanical strength precedes the deterioration of insulation strength, and accidents due to mechanical damage may occur. There is also fear. Therefore, it is not sufficient to simply monitor the deterioration of insulation strength due to partial discharge.

[Purpose of the invention]

In view of the above points, it is an object of the present invention to provide a highly reliable monitoring device for oil-filled appliances that can detect not only electrical abnormalities but also abnormalities due to mechanical deterioration.

[Summary of the invention]

In order to achieve the above objects, the present invention detects a partial discharge by using signals of both the current pulse accompanying the partial discharge of the oil-filled electrical appliance and the partial discharge sound, and also detects the excitation voltage and load current of the oil-filled electrical appliance. By detecting the low frequency component of 1 kHz or less of the partial discharge sound corresponding to this detected value, mechanical abnormalities due to strength deterioration of solid insulators can also be monitored. be.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 10 is an oil-filled electrical appliance such as an oil-immersed transformer, 11 is a bushing for drawing out the conductor of this oil-filled electrical appliance 10, 12 is a PD tag of the bushing 11, and 13 is a detector connected to the PD tag 12. It is impedance. Further, a detection impedance 14 is also connected between the tank 10h of the oil-filled electric appliance 10 and the ground point. The electrical signals detected by these detection impedances 13 and 14 are input to the partial discharge monitoring device 15. On the other hand, one or more acoustic sensors 16*, 16b such as microphones are attached to the outer surface of the 10m tank.
The acoustic signal detected thereby is also input to the partial discharge monitoring device 15. Reference numeral 17 denotes a load current detection device for an oil-filled electric appliance IQ such as a bushing CT, and a detection signal from this is input to a vibration monitoring device 18, which is also connected to the acoustic sensor via filters 19h and 19bf. Acoustic signals from 16m and 16b are input. In these filters 19m and 19b, 1 k of the acoustic signal
Only signal components below Hz are output.

Reference numeral 20 denotes an excitation voltage detection device using the PD tap 12 of the bushing 11, and a detection signal from this is input to the vibration monitoring device 18.

Next, the operation of the present invention will be explained. acoustic sensor 16
a and 16b have frequency characteristics as shown in FIG. 2, and are highly sensitive to partial discharge sounds around 100 to 200 kHz that occur when partial discharge occurs inside the oil-filled electrical appliance 10. ing. Now, when a partial discharge occurs inside the oil-filled electric appliance 10, a current pulse is detected from the detection impedance xs; x4Vc and inputted to the partial discharge monitoring device 15. At the same time, the acoustic sensor 16 a r 1θb detects partial discharge sound with a delay in propagation time in the oil in the gas tank lOa, and similarly inputs it to the partial discharge monitoring device 15 . The relationship between the current/arm pulse signal and the acoustic pulse signal from the acoustic sensor at this time is as shown in FIG. That is, the plurality of acoustic sensors 16a are delayed in detecting the current pulse.

16b are detected with time delays of Δt1 and Δt2, respectively. By observing this pulse generation i4 turn with a partial discharge monitoring device, it is determined whether it is the occurrence of a partial discharge or external noise, and if a partial discharge has occurred, an alarm output is generated. In addition, a plurality of acoustic sensors 1
6a.

It is also possible to calculate the location where the partial discharge occurs based on the time delay Δt, Δ1.1− of 16b.

On the other hand, an acoustic sensor 16 attached to the outer wall of tank 1σa
m, 16b detect the vibration level when the oil-powered energizer 10 is excited and energized. These vibrations generally have a frequency that is 10 times or less than the power supply frequency, and vary depending on the excitation voltage and load current as shown in FIGS. 4(a) and 4(b). Also,
The vibration level increases to the 5th level due to changes in the Young's modulus of solid insulators.
Changes as shown in the figure. Therefore, based on the detection signals of the excitation voltage detection device 20 using the PD tap 12''lt of the bushing 11 and the load current detection device 17, a vibration level set in advance corresponding to the output of each of the detection devices is selected. , filter 19a.

The vibration monitoring device 18 compares the output level of the filters 19b with the output level of the filters 19h and 19b, and if the output level of the filters 19h and 19b is larger, an alarm is output as a mechanical abnormality due to strength deterioration of the solid insulator. Acoustic sensor 16a.

Since 16b has the frequency characteristics shown in Fig. 2, l kH
In the region below z, the sensitivity is constant regardless of the frequency, and the frequency in level determination does not pose a problem.

〔Effect of the invention〕

As explained above, according to the present invention, a partial discharge is detected by both the current/arm pulse and the partial discharge sound accompanying the partial discharge of the oil-filled appliance, and the excitation voltage and load of the oil-filled appliance are detected. By detecting the current and detecting the low frequency component below 1 kHz of the partial discharge sound that corresponds to this detected value, it is possible to detect the strength deterioration of solid insulators, so in addition to detecting electrical abnormalities, it also detects mechanical Therefore, it is possible to obtain a highly reliable monitoring device for oil-filled appliances that can also detect physical abnormalities.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. Figure 2 is a frequency characteristic diagram of the acoustic sensor, Figure 3 is a waveform diagram of current pulse and acoustic pulse, Figure 4 (a),
(b) is a characteristic diagram showing the relationship between the vibration level and the excitation voltage and the load current, respectively, and FIG. 5 is a characteristic diagram showing the relationship between the Young's modulus of a solid insulator and the vibration level. 10...oil-filled electric appliance, 10a...tank, 11...
Bushing, 12...PD tag, 13.14...
Detection impedance, 15...Partial discharge monitoring device, 1
6a, 16b...Acoustic sensor, 17...Load current detection device, 18...Vibration monitoring device, 19*. 19b...filter, 20...excitation voltage detection device. Originator's agent Patent attorney Suzue Takehiko Figure 1 Figure 2 102 Yamanou [NiHzl Figure 3 Figure 4

Claims (1)

[Scope of Claims] A partial discharge monitoring device that detects partial discharge based on a current pulse accompanying partial discharge of an oil-filled electrical appliance and also a partial discharge sound;
a device for detecting the excitation voltage and load current of the oil-filled electrical appliance;
A monitoring device for oil-filled electrical appliances comprising a vibration monitoring device that monitors vibrations using detection signals of the excitation voltage and load current and a low frequency component of 1 kHz or less of the partial discharge sound.