JPH0732525B2 - Preventive diagnosis method for gas insulated switchgear - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preventive diagnosis method for a gas-insulated switchgear, and more particularly to a method suitable for automatically detecting the cause of an abnormality.

[Background of the Invention]

As a method of preventive diagnosis of a conventional gas-insulated switchgear, for example, as shown in JP-A-53-44773, the electromagnetically coupled probe is brought into close contact with an arbitrary position on the outer wall of the gas-insulated switchgear, and the discharge There is known a partial discharge detection device in which a pulse signal generated at this time is amplified by a pulse amplifier and displayed on an indicator. With this method, it is possible to detect that an abnormality has occurred, but not the cause of the abnormality. Moreover, since it is monitored by the indicator, it was not possible to detect automatically.

[Object of the Invention]

An object of the present invention is to provide a preventive diagnosis method for automatically detecting both an abnormality in a gas insulated switchgear and a cause of the abnormality without providing an additional mechanism inside the gas insulated switchgear.

[Outline of Invention]

In the present invention, the fact that the cause of the abnormality of the gas insulated switchgear is determined in relation to the partial discharge generation pattern is used. The discharge current output from the secondary side of the discharge current detecting current transformer connected to the ground wire of the case of the gas insulated switchgear is detected, and this discharge current is detected as the secondary of the voltage transformer of the gas insulated switchgear. Observed over one cycle of the AC voltage output during one cycle of the AC voltage output from the side, and the discharge current distribution state within one cycle and the cause of the abnormality of the gas insulated switchgear The partial discharge occurrence pattern related to is referred to and the abnormality and the cause of the gas-insulated switchgear are determined.

Example of Invention

 Representative examples of the present invention will be shown below.

In FIG. 1, the gas-insulated switchgear has a high-voltage main circuit conductor 1, a breaker 2, and a voltage transformer 3 built in a case 4 and insulated by a gas filled in the case. When an abnormality occurs in the gas insulated switchgear and a partial discharge occurs in the case 4, the discharge current passes through the ground wire 5 and flows to the ground.

In the present invention, in order to detect this partial discharge, the main circuit voltage related thereto is first detected. In other words, the voltage transformer secondary voltage 18 stepped down by the voltage transformer 3 is added to the square wave converter 9 to be converted into a square wave 19, which is applied to one input terminal of the AND gate 81. Since the clock pulse is constantly given from the clock source 10 to the other end of the AND gate 81 at a constant period, the clock pulse passes through the AND gate 81 and passes through the OR gate 16 while the output is being output to the square wave converter 9. Then
The counter 11 is operated so as to count the passing clock pulses, and after counting, this count value is written and stored in the register 14. Although the above description is for a positive wave, in the case of a negative wave, the output of the square wave converter 9 is applied to the NOT gate 17, and the output of the NOT gate 17 is applied to the AND gate 82.
In addition to one input end of 82, the output of the clock source 10 is applied to the other end of 82. The output of the AND gate 82 is applied to the counter 11 via the OR gate 16 in the same manner as in the case of the positive wave to count the passing clock pulses, and after counting, the count value is written in the register 14. In this case, the frequency of the clock source 10 is selected to be 8 times that of the AC voltage. On the other hand, the discharge current is input from the current transformer 6 installed on the ground wire 5. The output of 6 is applied to one input terminal of an AND gate 83 via the amplifier 7,
Since the pulse wave 20 which is the output of the counter 11 is applied to the other end of 83, the counter 12 counts the number of partial discharge pulses that pass in one pulse time zone. This count value is written in the register 13. The signals 18, 19, 20 of the respective parts have the waveforms shown in FIG.

Output of registers 13 and 14, output pulse of counter 11
20 is input to the calculator 15, and the calculator 15 shows the address corresponding to the count value of the register 14 and the presence or absence of the discharge pulse stored in the register 13 as shown in FIG. The discharge pattern is determined to detect the occurrence and cause of the abnormality.

That is, in FIG. 3, first, at step S1, it is judged whether or not it is the timing of data acquisition, based on the presence or absence of the data acquisition request flag. If it is not the fetch timing, the contents of the register 14 are read in step S2 when the standby state is set. The count value of the register 14 indicates what time zone the sine wave of one cycle is divided into several time zones. Register 13
The value of is taken in step S3. At step S4, whether or not the count value is stored in the register 13 is sequentially detected over one cycle of the AC voltage in each time zone determined by the count value of the register 14,
The cause of the abnormality of the gas insulated switchgear is determined by the correspondence between the count value of 14 and the count value of the register 13.

Fig. 4 shows the cause of abnormality and the pattern of partial discharge at that time. For example, in the case of void discharge, the period of π / 2 (rad) after the detected voltage waveform turns to a positive value and the negative value. It is known that a discharge pulse is observed during the period of π / 2 (rad) after turning to. Therefore, in step S4 of FIG. 3, the register 13 has a count value only when the count value of the register 14 is 1 or 5 (or 1, 2 and 5, 6) (0 is set in step S4). It is displayed that the count is present and the x is not present.), And that the void discharge is displayed and output in step S5. Cause of abnormality
If it is a sharp edge in SF ₆ , it is a needle-shaped metal piece, or if there is poor contact with the metal part
Since the discharge pulse is observed at the voltage phase shown in the figure, in step S4 of FIG. 3, the discharge pattern is obtained by successive comparison of the count values of the register 14 and the register 13, as in the void discharge. Are separated and displayed and output respectively at steps S6, S7 and S8. When a discharge pattern other than the above is observed, the cause is unknown, and that effect is displayed and output in step S9.

The above is an explanation of the four discharge patterns that are currently unknown, but if the cause of the abnormality due to the discharge pattern is further understood in the future, it can be dealt with by making the address of register 14 visible so that the discharge pattern can be seen. is there.
In this way, it is possible to automatically detect the abnormality occurrence and the cause of the abnormality of the gas insulated switchgear from the secondary voltage of the voltage transformer and the secondary current of the current transformer connected to the ground wire.

〔The invention's effect〕

According to the present invention, it is possible to automatically detect both the abnormality of the gas insulated switchgear and the cause of the abnormality and perform a preventive diagnosis without providing an additional mechanism inside the gas insulated switchgear.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the principle of the present invention, FIG. 2 is a diagram showing a circuit waveform, FIG. 3 is a flow chart diagram, and FIG. 4 is a diagram showing an abnormal source and a partial discharge generation pattern. . 1 ... Main circuit conductor, 2 ... Breaker, 3 ... Voltage transformer, 4 ... Case, 5 ... Ground wire, 6 ... Current transformer,
7 ... Amplifying and shaping device, 8 ... AND gate, 9 ... Square wave converter, 10 ... Clock, 11 ... Counter, 12 ... Counter, 13 ... Register, 14 ... Register, 15 ...
… Calculator, 16 …… Orgate.

Claims (1)

[Claims] 1. A discharge current output from a secondary side of a discharge current detecting current transformer connected to a ground wire of a case of the gas insulated switchgear is detected, and this discharge current is a voltage of the gas insulated switchgear. It is observed for one cycle of the AC voltage output from the secondary side of the transformer for one cycle of the AC voltage, and the distribution state of the discharge current in the one cycle and the gas are observed. A preventive diagnostic method for a gas-insulated switchgear, characterized in that an inquiry is made with respect to a partial discharge occurrence pattern related to the cause of an abnormality in the insulation switchgear to determine the abnormality and the cause of the gas-insulated switchgear. .