JPS604433B2 - Partial discharge detection device for oil-filled electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a partial discharge detection device for oil-filled electrical equipment that is constantly installed in oil-filled electrical equipment during actual operation.

For example, if partial discharge occurs in high-voltage oil-filled electrical equipment such as a transformer during actual system operation, this may trigger an insulation breakdown accident.

Once such an accident occurs, it can have extremely serious consequences, such as disruption or shutdown of the power system. For this reason, in oil-filled electrical equipment during actual system operation, partial discharge is detected to completely prevent equipment breakdown accidents.
By the way, there are two conventional techniques for detecting a partial discharge occurring inside an oil-filled electrical device during actual operation: an electrical method and an acoustic method. The former is a method in which the current pulse generated in the electrical circuit when partial discharge occurs in oil-filled electrical equipment is detected using a detection impedance connected to the PD tap of the bushing or a detection impedance connected between the neutral point and ground. It is. However, with this electrical method, since the power transmission line is connected to the transformer in actual operation, the overhead line acts as an antenna, and induction noise and airborne corona from the transmission line can enter the partial discharge detection circuit, causing malfunction. Sometimes. The other acoustic method involves installing a microphone on the tank wall of the equipment and using this microphone to detect the partial discharge sound generated inside the equipment. It has less impact and is more suitable for on-site testing than the electrical methods mentioned above. However, this acoustic method also has the disadvantage that it is sensitive to the sound of foreign objects hitting the tank wall, the sound of animals moving, or the sound of rain. There is also a method of detecting the current pulse caused by the occurrence of partial discharge, receiving the discharge sound that comes later than this using a microphone, and monitoring these signals with an oscilloscope. It requires a skilled worker to monitor the signals, and since these signals disappear instantly as the partial discharge disappears, they are too unreliable to be permanently installed in oil-filled electrical equipment in actual operation. Ta. The present invention has been developed in consideration of the above-mentioned points, and its purpose is to be able to detect partial discharges occurring in oil-filled electrical equipment without being affected by the atmospheric corona of power transmission lines or the sound of rain. The object of the present invention is to obtain a partial discharge detection device for oil-filled electrical equipment that is highly reliable and can be permanently installed in oil-filled electrical equipment that is in actual operation.

That is, the partial discharge detection device according to the present invention takes into account that when a partial discharge occurs inside the device, the discharge sound detected by the converter is delayed by the propagation time in oil from the generation position to the converter installation position, The current pulse signal that is instantaneously detected when a partial discharge occurs is delayed by a time corresponding to the oil propagation time mentioned above, and when the discharge sound signal and the current pulse signal are synchronized, the current pulse signal is automatically detected. This system determines that it is a partial discharge, distinguishes it from other noise signals, and issues an output that activates an alarm.

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 11 is oil-filled electrical equipment such as a transformer,
Insulating oil is housed inside along with the electric circuit 11a. When a partial discharge occurs in this oil-filled electrical equipment 11, a current pulse instantaneously generated in the electric circuit 11a is transmitted through a detection impedance (not shown) connected to the PD tap of the high-voltage bushing or on the high-voltage side of the electric circuit 11a. A corona detector 14 is detected by a detection impedance 12, such as a Gosky coil, connected between the sex point and ground, and is connected to a coaxial cable 13 to prevent external noise from being picked up.
guided by. This corona detector 14 also has an amplification function. The output side of the corona detector 14 is connected to a gate pulse generator 15 which generates a gate pulse whose rise delay time and duration can be set in advance by the above-mentioned current pulse. The gate pulse generated by the gate pulse generator 15 is generated at least later than when the current pulse is generated, taking into account that the discharge sound is delayed by the propagation time in the oil from the generation position to the converter mounting position. The duration time is set to the maximum propagation time in oil based on the sound velocity in oil of 1.5 m/sec, the size of the tank, and the mounting position of each transducer, and the rise delay time is set to 0.2, for example, as shown in Figure 2a.
The signal is set to S of ~1 and the duration is set to 3 to 20 mS, and is led to the AND circuit 16. On the other hand, the discharge sound generated when a partial discharge occurs propagates through the oil and reaches the tank wall, and a plurality of transducers 17, such as ultrasonic microphones, are installed on the tank wall at appropriate intervals. Detected by 18.

In this case, since the transducers 17 and 18 are mounted on the tank wall at appropriate intervals, the order in which the discharge sound is received differs depending on the position where the partial discharge occurs, and there may be some transducers that do not receive the sound. The output signals of each converter 17 and 18 are passed through a coaxial cable 19 to remove low frequencies such as tank vibration noise, and passed through pass filters 20 and 21 to amplifiers 22 and 2.
3 and guided to trigger pulse generators 24 and 25. The trigger pulse generators 24, 25 utilize the first rising edge of the converter output signal to generate converter signal pulses (less than 0.1 mS) as shown in FIG. 2b. The converter signal pulses generated by the trigger pulse generators 24 and 25 are guided to an AND circuit 16. Furthermore, between the amplifiers 22 and 23 and the trigger pulse generators 24 and 25 and the AND circuit 1
A recorder 26 connected to the output side of the converter 6 is used to see which converter's output signal generated the alarm or the time. Therefore, when a partial discharge occurs in the oil-immersed electrical equipment 11, the converter signal pulse caused by the discharge sound delayed by the propagation time in the oil and the gate pulse generated by the delayed current pulse are synchronized, so the AND circuit 16
determines that a partial discharge has occurred and outputs an output signal that activates an alarm, etc.

On the other hand, even if an airborne corona on a power transmission line or the sound of rain occurs, this device only outputs either a current pulse or a converter signal pulse, so the AND circuit 16 does not operate and partial discharge occurs. It is not determined. In addition, large external noises caused by the operation of chopsticks, disconnectors, disconnectors, etc. may enter electrical circuits or signal cables (current pulses and converters), but the resulting current pulses and converter signal pulses are Since there is no time difference, the AND circuit 16 does not operate and does not determine that a partial discharge has occurred. As described above, according to the partial discharge detection device for oil-filled electrical equipment according to the present invention, it is possible to detect the occurrence of partial discharge without being affected by external noise such as the atmospheric corona of power transmission lines and the sound of rain, and moreover, it is possible to detect the occurrence of partial discharge while Since partial discharge can be detected automatically without the need for personnel, it is ideal for permanent installation in oil-filled electrical equipment that is in actual system operation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a partial discharge detection device for oil-filled electrical equipment according to the present invention, and FIG. 2 is a waveform showing an example when the partial discharge detection device for oil-filled electrical equipment according to the present invention detects partial discharge. It is a diagram. 11...Oil-filled electrical equipment, 15...Gate pulse generator, 16...AND circuit, 17, 18
......Converter, 24,25...Trigger pulse generator. Spear/Figure O 2

Claims (1)

[Claims] 1. Oil-filled electrical equipment that houses an electrical circuit and insulating oil inside, and multiple converters that detect the discharge sound and generate electrical signals when partial discharge occurs within this oil-filled electrical equipment. and a device for detecting current pulses occurring in the electrical circuit; a trigger pulse generator for receiving an output signal of the converter and generating a converter signal pulse; and a trigger pulse generator for receiving an output signal from the device for detecting the current pulse; a gate pulse generator that generates a gate pulse whose rise delay time and duration are set to predetermined values; and a gate pulse generator that generates a signal when the output signal of the trigger pulse generator and the output signal of the gate pulse generator are synchronized. A partial discharge detection device for oil-filled electrical equipment consisting of an AND circuit that generates partial discharge.