JPH0216475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic internal partial discharge monitoring device for a transformer that automatically monitors the occurrence of partial discharge (hereinafter referred to as PD) occurring inside the transformer.

With the increase in demand for electricity in recent years, transformers used in power transmission systems are also becoming larger in capacity and ultra-high voltage.
Therefore, if a serious accident occurs in power transmission equipment, it will have a large impact on the power transmission system and society, and accidents must be prevented as much as possible. In recent years, there has been a trend toward preventing accidents that completely destroy transformers and other power transmission equipment by detecting them in advance.

In general, a precursor to a total circuit breakdown phenomenon in a transformer is PD that occurs inside the transformer. Therefore, if we monitor the occurrence of this PD,
This can be one way to prevent the phenomenon of complete circuit failure of the transformer. In FIG. 1, reference numeral 1 denotes a sealed tank filled with insulating oil 1d and containing a transformer main body 2, lead wires 3, and the like. Transformer body 2
is connected to the air bushing 4 via a lead wire 3. A plurality of corona microphones 5 (usually 3 to 6) are attached to the outer wall of the tank 1 at key points. The corona microphone 5 has functions such as detecting PD ultrasonic waves generated within the tank 1, converting them into electrical signals, and amplifying them. Furthermore, the current pulse accompanying the PD phenomenon is detected by the detector 7 from the bushing tap 6 or the neutral point of the transformer. The detected ultrasonic waves and current pulses are transmitted to the monitoring device main body 9 via the transmission cable 8.
transmitted to. Internal PD in such a configuration
In monitoring equipment, e.g.
Discrimination between PD and PD generated outside the transformer (for example, airborne corona, surge, etc.) is performed within the monitoring device main body 9 described above. The criteria for this judgment are:
This depends on whether there are both a detection signal from the corona microphone 5 and a current pulse detection signal from the detector 7. However, inside the transformer,
As is well known, there is an on-load tap changer 10,
During the tap switching operation of the on-load tap changer 10, an operating sound is generated and a current change occurs. Therefore, the corona microphone 5 described above detects the operating sound, and the current pulse detector 7 also detects the current pulse, and the main body of the monitoring device is detected as if a PD had occurred inside the transformer tank 1. 9 makes the decision. This causes the monitoring device 9 to misidentify the occurrence of internal PD. Another example where operating noise is generated inside the transformer and current pulses are detected is when the oil circulation pump 11 is in operation. The present invention was made in view of the above problems.
The purpose of the present invention is to provide a partial discharge monitoring device for a transformer that does not cause misidentification due to the operation of auxiliary equipment of the transformer, such as a mechanically operated on-load tap changer or oil circulation pump that is attached to the transformer. shall be.

An embodiment of the present invention will be described below. During mechanical operation of the load tap changer 10, oil circulation pump 11, etc., operating noise is generated inside the transformer, and current pulses are detected by the detector 7. Therefore, when the auxiliary equipment attached to the transformer main body is mechanically operated, the monitoring device main body 9 is configured to stop monitoring for a certain period of time until the mechanical operation of the auxiliary equipment is completed. By doing this, for example, even if an operating sound is heard inside the tank 1 and a current pulse is detected during the mechanical operation of the on-load tap changer 10, the monitoring of the monitoring device main body 9 is canceled during that time. Therefore, there is no risk of misidentification of the monitoring device itself. In addition, the time required to release the monitoring device itself is, for example, several milliseconds or less when the oil circulation pump 11 is starting up, and it only takes a few milliseconds when the tap changer 10 is operating. There is almost no risk that functionality will be degraded. In FIG. 2, which will now be described in more detail about the monitoring operation cancellation system of the monitoring device main body 9, the signal on CH1 represents, for example, a control signal for a tap changer. Among them, numeral 12 corresponds to the control signal CH2 to the monitoring device main body 9, and is generated in advance by time T1 by the tap switching operation signal 13. This T1 time may be 1 mS or less. The monitoring device main body 9 is
When receiving 12 signals of CH1, for example, all signals from transmission path 8 are ignored and the monitoring operation is canceled. Then, after the operating time of the tap changer 10 ends (after T2), a signal of 14 is generated in CH2 to restore the automatic monitoring function of the main body of the monitoring device. As described above, several milliseconds is sufficient for this time T2.

As explained above, according to the present invention, the load tap changer, oil circulation pump, etc. that are attached to the transformer body and are generally operated as the load of the transformer increases or decreases.
It is possible to provide a highly reliable automatic partial discharge monitoring device for a transformer that does not cause misunderstandings regarding internal partial discharge monitoring due to the mechanical operation of the transformer main body auxiliary equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an internal partial discharge monitoring device for a transformer, and FIG. 2 is a diagram illustrating the operating principle of the internal partial discharge monitoring device for a transformer according to the present invention. 1... Sealed tank, 2... Transformer body, 3...
Lead wire, 5...corona microphone, 7...current pulse detector, 9...monitoring device body, 10...load tap changer, 11...oil circulation pump.

Claims (1)

[Scope of Claims] 1. A transformer main body is housed in a closed tank filled with an insulating medium, and partial discharge occurring within the closed tank is automatically detected by acoustic means and electric means for detecting current pulses. In the automatic internal partial discharge monitoring device for a transformer that detects using at least one of the transformer, the transformer is attached to the transformer main body and operates mechanically, such as a load tap changer, the insulating medium circulation pump, etc. Canceling the monitoring operation of the monitoring device main body to which the acoustic means and the electrical means are connected for a certain period of time from the start of the mechanical operation of the auxiliary equipment of the main body;
An automatic internal partial discharge monitoring device for a transformer characterized by preventing misidentification of the occurrence of internal partial discharge. 2. The automatic internal partial discharge monitoring device for a transformer according to claim 1, wherein the acoustic means is a corona microphone.