JP2617906B2 - Transformer operation monitoring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer operation monitoring device, and more specifically, monitors a tap switching time by a switching switch of a transformer tap switching device under load. Thus, the present invention relates to a transformer operation monitoring device that performs early abnormality detection related to transformer operation.

[Conventional technology]

2. Description of the Related Art An on-load tap switching device of a transformer (hereinafter referred to as a tap changer) generally includes a switching switch and a tap selector. Further, an electric motor for driving the tap changer is provided. The tap changer performs the tap change without interrupting the transformer circuit when the voltage ratio is changed due to a load change during the application of power to the transformer.

 Next, the operation of the tap changer will be described.

When the voltage ratio needs to be changed during the power application of the transformer, for example, a control device (not shown) issues a load tap switching activation signal. When the on-load tap change start signal is issued, the drive signal of the motor is output for one cycle of the tap change operation of the tap changer, for example, about 5.5 seconds. By driving the motor, a tap selector is first operated to select a predetermined tap,
Next, the switching switch is operated to switch the electric circuit, and the tap switching operation is performed. At this time, the tap selection operation by the tap selector is performed within about 3.5 seconds from the generation of the on-load tap switching activation signal, and the switching operation of the electric circuit by the switching switch is performed by about 4.5 seconds from the generation of the on-load tap switching activation signal. This is performed within about several tens of milliseconds after the lapse of seconds. The time of several tens of milliseconds is the actual switching time by the switching switch.

Here, the switching operation of the electric circuit by the switching switch is performed in such a manner that the tap switching mechanism is normally operated in order to temporarily short-circuit between the switching target taps of the transformer tap winding through the resistor or the reactor in the switching switch. If it does not operate, an excessive short-circuit current may occur between the taps of the tap winding, leading to a major accident.

Conventionally, in order to prevent such an accident and operate the transformer normally, the number of times the tap changer has been operated has been conventionally monitored, and when the specified number of times has been reached, parts are replaced, etc. Although monitoring of the time including the switching operation preparation time is performed, it is not monitoring of the actual tap switching time with a switching switch as short as several tens of milliseconds, so it is difficult to grasp the precursory phenomenon of the abnormality, and the abnormality prediction method Was not enough.

On the other hand, at the time of a patrol inspection by a person, an abnormality may be found from the tap switching sound as a difference from the normal state.However, to detect the abnormality by hearing, it is necessary for the person to go to the vicinity of the transformer, and furthermore, Only when there are various conditions such as that tap change is performed and that the patrol member can judge normal / abnormal from the switching sound of the target tap engineer, the patrol member's skill level is required. However, this method is not sufficient as an abnormality detection method, such as not always monitoring.

[Summary of the Invention]

The present invention focuses on the above points, and aims to automatically detect an abnormality of a tap engine at an early stage. A vibration or acoustic detector is arranged on the tap engine and synchronized with a tap change start signal at load. Then, the converted signal of the detector and the load current level signal of the transformer are taken in, and based on these signals, an equivalent tap switching time in which a variation due to the load current is removed is calculated, and the calculated equivalent tap switching time is calculated. It is an object of the present invention to provide a transformer operation monitoring device which determines whether there is an abnormality in a tap engine based on time.

(Example of the invention)

FIG. 1 shows a first embodiment of the present invention, in which a tap switching switch 2 and a tap selector 4 are connected to a tap switching drive 2 disposed above a tank 1 of a tap engine.
Are connected to each other, and the tap changeover switch 3 and the tap selector 4 are housed in the tank 1 in which the insulating oil is housed to form a tap engine.

A vibration detector 5 is mounted on the outer wall of the tank 1, and an electrical processing unit 6 converts a signal output from the vibration detector 5 into a predetermined electric level signal according to the magnitude of the vibration. 7, a filter circuit 8, a signal comparison circuit 9, a gate circuit 11 driven by the signal comparison circuit 9 to open and close an output of a pulse generation circuit 10 to a pulse counter circuit 12, an output of the pulse counter circuit 11 and a tap switching start signal 14, and It comprises a judgment processing circuit 13 to which the output of the load current detector 15 that has passed through the second signal conversion circuit 16 is input. The second signal conversion circuit 16 receives the signal from the load current detector 15 and converts the signal into a predetermined electric level signal according to the magnitude of the transformer load current. The solid line of the arrow indicates the signal transmission path, the broken line indicates the reset signal path from the judgment processing circuit to the pulse counter circuit 12, and i _L indicates the transformer charge current.

Next, the operation will be described. When the voltage ratio needs to be changed during the power application of the transformer, for example, a control device (not shown) issues an on-load tap switching activation signal 14. When the on-load tap switching start signal 14 is issued, a drive signal for the electric motor is output for one cycle of the tap switching operation of the tap changer. When the electric motor is driven, the tap selector 4 is first operated to select a predetermined tap. Then, the mechanical energy stored by the spring or the like in the tap switching driving device 2 is released, and the contact of the switching switch 3 is released. Is switched, and the electric circuit is switched. In the switching operation of the electric circuit by the switching switch 3, a pressure rise occurs due to the generated mechanical force and the arc generated between the contacts, and the tank 1 wall is vibrated through the insulating oil in the tank 1. Then, after the switching operation of the electric circuit is completed, the vibration of the tank 1 wall is gradually attenuated. Therefore, the vibration of the tank 1 wall caused by the switching operation of the electric circuit by the switching switch 3 starts rising after the switching of the tap is started by the switching switch 3, and the switching of the tap is completed by the switching switch 3. Thereafter, it gradually attenuates, and returns to a steady state after a lapse of a predetermined time.

The vibration of the wall of the tank 1 is detected by the vibration detector 5, converted into an electric level signal by the signal conversion circuit 7, and output to the signal comparison circuit 9 through the filter circuit 8. The signal comparison circuit 9 opens the gate circuit 11 when the input signal level is equal to or higher than the reference value, and outputs a pulse from the pulse generation circuit 10 to the pulse counter circuit 12. The pulse counter circuit 12 accumulates the pulse signals input through the gate circuit 11 and outputs the accumulated signal to the judgment processing circuit 13.

Here, vibration and sound are also generated during the trip / insertion operation in the tap selection operation of the tap selector 4, and this vibration is detected by the vibration detector 5. Therefore, in order to prevent noise, for example, an erroneous signal caused by the operation of the tap selector 4, the judgment processing circuit 13 resets the pulse counter circuit 12 when receiving the load tap switching start signal 14, After a predetermined time has elapsed since the tap switching start signal 14 was received, that is, immediately before the tap switching operation of the switching switch 3 was started, the accumulation of the pulse signals of the pulse counter circuit 12 was started. The output from the deemed pulse counter circuit 12 is read, and at the same time, the load current value is read by the load current detector 15.
The signal is taken in via the signal conversion circuit 16.

Subsequently, the judgment processing circuit 13 calculates a substantial tap switching time corresponding to the actual tap switching time of the switching switch 3 from the pulse counter output value.

Here, in the operation of the transformer, load fluctuations caused by the load current i _L, the arc energy is varied, thereby varying the vibration of the tank 1 wall. That is, even when the tap changer is operating normally, since substantially the tap switching time t _x, which is calculated based on the detection signal of the vibration detector 5 fluctuates by a load current i _L, varies according to the load current min it is necessary to calculate the equivalent tap switching time t _e has been removed. The equivalent tap switching time t _e and the effective tap switching time t _x are given by t _e = t
It represented as _{x (1-f (i L} )).

Therefore, the determination processing circuit 13 calculates the equivalent tap switching time t _e by subtracting the increase t _x f (i _L ) due to the load current from the calculated real tap switching time t _x . The equivalent tap switching time t _e has a actual tap switching time equivalent to the switching switch 3 removes the variation due to the load current.

At this time, if the tap switching mechanism is not operating normally, for example, if the current limiting resistance is broken, current limiting cannot be performed,
If an excessive short-circuit current occurs between the taps, the arc energy increases and the calculated real tap switching time becomes longer, or even if the tap switching time becomes longer, the calculated real tap switching time becomes longer. .

Therefore, the judgment processing circuit 13 compares the set tap switching time, which is the preset tap switching time of the switching switch 3 in the normal state, with the calculated equivalent tap switching time, and determines the equivalent tap switching time. Is longer than a predetermined N times the set tap switching time, the tap changer is determined to be abnormal and an appropriate alarm is output.

FIG. 2 shows a second embodiment. In the embodiment of FIG. 1, it is assumed that the abnormality of the tap changer is determined by comparing the set tap switching time set in advance by the determination processing circuit 13 with the calculated equivalent tap switching time. A data storage / arithmetic processing circuit 17 is further connected to the judgment processing circuit 13.

The data storage / arithmetic circuit 17 stores the data of the equivalent tap switching time calculated by the determination processing circuit 13, obtains a frequency distribution as shown in FIG. 3 from the stored data, and further obtains a standard deviation value σ. I have. Then, the judgment processing circuit 13
It is calculated whether or not the equivalent tap switching time calculated by the above is longer than the average value by several times the standard deviation value σ (for example, 3σ), and the equivalent tap switching time is standard deviation value σ from the average value.
If it is longer than several times, it is determined that an abnormality has occurred in the tap changer. With such a device,
Further more accurate abnormality prediction can be performed.

As described above, in the first and second embodiments, the vibration is detected by the vibration detector 5 generated in the tank 1. Good. The third embodiment shown in FIG.
Instead of the vibration detector 5 in the figure, an acoustic detector 5a is arranged near the tank 1, and the other parts are the same as those in FIG. 1, and the same effects can be obtained.

The vibration detector 5 in the second embodiment shown in FIG.
The same applies to the case where is replaced with an acoustic detector arranged near the tank 1.

〔The invention's effect〕

As described above, the present invention captures a signal-converted output of a detector and a load current level signal of a transformer in synchronization with a load tap switching start signal, and detects a variation due to a load current based on these signals. Since the removed equivalent tap switching time is calculated, and the abnormality of the tapping engine or the sign of the abnormality is determined based on the calculated equivalent tap switching time, automatic and high-precision early abnormality detection of the transformer operation is performed. Can be.

[Brief description of the drawings]

FIG. 1 is a connection diagram of the first embodiment of the present invention, FIG. 2 is a connection diagram of the second embodiment, FIG. 3 is a diagram showing a histogram of tap switching time-number of operations, and FIG. FIG. 9 is a connection diagram of the third embodiment. 1 ... Tank of tap change device under load, 5 ... Vibration detector, 5a ... Sound detector, 6 ... Electrical processing unit, 7 ...
1st signal conversion circuit, 8 filter circuit, 9 signal comparison circuit, 10 pulse generation circuit, 11 gate circuit,
12 ... Pulse counter circuit, 13 ... Decision processing circuit, 14 ...
... Tap switching start signal, 15 ... Load current detector, 16 ...
... second signal conversion circuit, 17 ... data storage / operation processing circuit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (5)

(57) [Claims] 1. A vibrating or acoustic detector disposed in a tap switching device under load of a transformer, a signal-converted output of the detector and the transformer in synchronization with a tap switching start signal under load. Load current level signals, and based on these signals, calculate the equivalent tap switching time from which the variation due to the load current has been removed, and determine from the calculated equivalent tap switching time whether the load tap switching device has an abnormality. A transformer operation monitoring device comprising: an electrical processing unit for determining; A first signal conversion circuit for converting an output signal of the detector into a predetermined electric level signal; and a gate circuit when an output of the first signal conversion circuit via a filter circuit exceeds a predetermined value. A signal comparison circuit to be opened, a pulse counter circuit to which an output of the pulse generation circuit is input via the gate circuit, and a reset of the pulse counter circuit in response to a load tap switching start signal, A determination processing circuit for calculating an equivalent tap switching time based on the load current level signal, and determining whether there is an abnormality in the on-load tap switching device based on the calculated equivalent tap switching time. Transformer operation monitoring device according to the item. 3. Statistical processing is performed by storing the equivalent tap switching time calculated by the judgment processing circuit, and whether or not there is an abnormality in the on-load tap switching device based on an allowable value of the equivalent tap switching time from the statistical processing. 2. The transformer operation monitoring device according to claim 1, further comprising an arithmetic processing means for judging. 4. The vibration detector according to claim 1, wherein said detector is a vibration detector mounted on a tank wall of said load tap changer.
Transformer operation monitoring device according to the item. 5. The transformer operation monitoring device according to claim 1, wherein the detector is an acoustic detector arranged near a tank of the on-load tap switching device.