JPH0226219A - Trouble diagnosing device for gas insulated electric facility - Google Patents

Abstract

PURPOSE:To prevent the influence of an external noise and to determine the absolute amount of an inner corona by outputting the difference of the outputs of a pair of sensors as a signal, and inhibiting an output when the polarities of the outputs of current sensors are the same. CONSTITUTION:A pair of sensors 2a, 2b and 2c, 2d grounded at a position not disconnected in a circuit manner by a circuit breaker 22 are provided, and subtracting means 4 for outputting the difference of the pair, and polarity identifying means 5 for producing an output when the polarities of the outputs of the pair are the same are provided in a trouble diagnosing device body 3. When the means 5 produces the output, the output of the means 4 is blocked by gate means 6. Except it, this output is input to discriminating means 7 through a multiplexer 15 and A/D converter 16 to measure the absolute amount of an inner corona.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a failure diagnosis device for gas-insulated electrical equipment used in substations, factories, etc.

[Conventional technology]

Conventional failure diagnosis devices for gas-insulated electrical equipment include those using current sensors and those using ultrasonic sensors.

A failure diagnosis device for gas-insulated electrical equipment using a conventional current sensor will be explained based on FIG.

As shown in FIG. 5, this failure diagnosis device for gas-insulated electrical equipment is configured to include current sensors 52a, 52b, and 52c attached to grounding wires 51a, 51b, and 51c, respectively.

Further, the gas insulated electrical equipment is inserted between the container 55, the shield 56, the conductor 57, and each container 55,
It consists of an insulating spacer 58 used as a partition, a circuit breaker 59, and a switch 60. 61 represents the earth.

The insulating spacer 58 is inserted between each container 55 and fixed at the flange portion (not shown) of the container with bolts and nuts (not shown). Then, sulfur hexafluoride (SF4) gas is sealed in the space surrounded by each container 55 and insulating spacer 58. ! are connected. Further, the insulating spacer 58 is used as a spacer to fix the conductor 57, and the insulating spacer 58 is used as a spacer to fix the conductor 57.
The space surrounded by 8 is sealed.

In this gas-insulated electrical equipment, internal corona occurs between the conductor 57 and the container 55 due to deterioration of the insulating spacer 58.

Then, the current generated by the internal corona is transmitted through the surface of the insulating spacer 51 and the grounding wire 51a, 51b or 51
It flows to the ground 61 via c. The current sensor 52a, 52b, or 52c of the failure diagnosis device for gas-insulated electrical equipment detects the current flowing through the grounding wire 51a, 51b, or 51c, and outputs the detected current to the failure diagnosis device (not shown). The failure diagnosis device is a current sensor 52a.

The output from 52b or 52c is manually input to determine the magnitude and number of times the current generated by this internal corona occurs, thereby diagnosing the failure of gas-insulated electrical equipment.

Next, a failure diagnosis device for gas-insulated electrical equipment using a conventional ultrasonic sensor will be described.

The failure diagnosis device for gas insulated electrical equipment using this ultrasonic sensor is the grounding wire 51a of the failure diagnosis device for gas insulated electrical equipment using the above-described current sensor.

Current sensor 52a attached to each of 51b and 51c
, 52b, 52c, an ultrasonic sensor is attached to each insulating spacer 58 inserted between each container 55.

The rest of the configuration is similar to the failure diagnosis device for gas-insulated electrical equipment using the above-mentioned current sensor.

According to the configuration of this failure diagnosis device for gas-insulated electrical equipment,
Each ultrasonic sensor detects the sound of internal corona generated on the surface of the insulating spacer 58 between the conductor 57 and the container 55 due to deterioration of the insulating spacer 58 of the gas-insulated electrical equipment.

Then, a failure diagnosis device determines the loudness and number of times the sound generated by this internal corona occurs, and diagnoses the failure of the gas-insulated electrical equipment.

[Problem to be solved by the invention]

Gas insulated electrical installations using conventional current sensors have a conductor 5
When external noise arrives at 7, the current generated by the external noise, similar to the current generated by the internal corona, freezes the surface of the insulating spacer 58 between the conductor 57 and the container 55, and connects to the ground 51a.

5] flows to the ground 61 via b and 51c. At this time,
Current sensors 52a, 52b, and 52c detect the current generated by this external noise and apply an output to the fault diagnosis device without distinguishing it from the current generated by the internal corona. As a result, there was a problem in that the influence of external noise could not be removed and the occurrence of internal corona could not be accurately detected.

In addition, each of the grounding wires 51a, 51b, and 51c is independent in terms of circuit, forming a multi-point grounding system, and the current generated by the internal corona is transmitted to each of the grounding wires 51a, 51b, and 51c.
Since the current is shunted to 51c, there is a problem in that it is difficult to determine the absolute amount of current.

In addition, a failure diagnosis device for gas-insulated electrical equipment using an ultrasonic sensor has a sound-to-noise ratio (S/N) of the ultrasonic sensor.
) and is susceptible to external sounds such as rain, making it impossible to accurately detect sounds caused by internal corona.

Furthermore, the acoustic transmission impedance changes due to the tightness of the bolts and nuts of the flange portion 55 of the container and structural influences, making it difficult to quantitatively evaluate the sound generated by the internal corona.

Therefore, an object of the present invention is to provide a failure diagnosis device for gas-insulated electrical equipment that is not affected by external noise, is capable of quantitatively evaluating the occurrence of internal corona, and is capable of determining the absolute amount of internal corona.

[Means to solve the problem]

The fault diagnosis device for gas-insulated electrical equipment of the present invention includes a pair of current sensors each attached to a pair of grounding wires connected to locations that are not separated in terms of circuitry, and subtraction means for calculating the difference in output of each current sensor. , a polarity identifying means for outputting an output when the outputs of the current sensors have the same polarity; a gate means for blocking the output of the subtracting means in response to the output of the polarity identifying means; and determining the output of the gate means. The configuration includes determination means.

(Function) According to the structure of the present invention, each of the pair of current sensors is attached to a pair of ground wires connected to a point that cannot be separated from each other in terms of the circuit, so that the current flowing through each ground wire generated by external noise can be avoided. The current flows in the same direction with respect to the pair of ground wires, and the output of each current sensor has the same polarity.Also, the current flowing in each ground wire generated by the internal corona flows in different directions with respect to the pair of ground wires. , the output of each current sensor has a different polarity.Then, the output of each current sensor is differenced by a pull means, and the output is added to a gate means when the output of each sensor has the same polarity by a polarity discrimination means. The gate means blocks the output of the pulling means in response to the output of the polarity identifying means, and the determining means determines the output of the gate means, so that when the outputs of the current sensors have the same polarity.

In other words, when there is external noise, the gate means is in a closed state and no signal is transmitted to the determination means, and when the outputs of the current sensors have different polarities, that is, when there is an internal corona, the polarity identification means outputs an output to the gate means. The sum of the absolute amounts of the outputs of the respective current sensors is output from the pulling means without adding , and the sum of the absolute amounts of the outputs of the respective current sensors also appears in the output of the gate means. will be judged. Therefore, the output from each current sensor due to external noise is not transmitted to the determination means, but only the output from each current sensor due to the occurrence of internal corona is transmitted.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A failure diagnosis apparatus for gas-insulated electrical equipment according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

As shown in FIG. 1, this failure diagnosis device for gas-insulated electrical equipment uses a pair of grounding wires 1a that are grounded at a location that is not disconnected from the circuit by a circuit breaker 22.

It includes a pair of current sensors 2a, 2b and 2c, 2d attached to 1b, lc, and ld, respectively.

As shown in FIG. 2, the current sensors 2a, 2b, and 2c are provided inside the main body 3 of the failure diagnosis device.

2d's output SA, Sl and Sc, So, the output of each current sensor 2a, 2b and 2c2d - S, , S, and SC, S11<7) Outputs when the polarities are the same. polarity identification means 5.

Furthermore, the configuration includes a gate means 6 for blocking the output of the pulling means 4 in response to the output of the polarity identifying means 5, and a determining means 7 for determining the output of the gate means 6. A, B, C, and D shown in FIGS. 1 and 2 indicate signal lines connected from the current sensors 2a2b, 2c, and 2d to the failure diagnosis apparatus main body 3, respectively.

Next, the specific structure and operation of the failure diagnosis apparatus main body 3 for gas-insulated electrical equipment will be explained in detail with reference to FIGS. 2 to 4.

As shown in FIG. 2, this failure diagnosis apparatus main body 3 for gas-insulated electrical equipment includes a pair of current sensors 2a, 2b, and 2c.
, 2d, and a pair of variable gain amplifiers 9 and 10. It includes a triggering means 4 for amplifying, which is made of, for example, a differential amplifier with a variable gain, and a delay circuit 11 for delaying the output of the triggering means 4. Further, a polarity identifying means 5, a gate means 6, for example a field effect transistor, which passes or blocks the output of the delay circuit 11, that is, the output of the pulling means 4 in response to the output of the polarity identifying means 5, and a multiplexer 15. , an analog-to-digital converter 16, and a central processor unit (C
PU).

Moreover, as shown in FIG.
and an insulating spacer 24 inserted between each container 20 and used as a partition wall. 25
indicates the earth.

As in the conventional example, the insulating spacer 24 is inserted between each container 20 and fixed at the flange portion of the container 20 with bolts and nuts (not shown). The space sealed by each container 20 and the insulating spacer 24 is filled with sulfur hexafluoride (SF4) gas and is insulated. Further, the insulating spacer 24 is connected to the conductor 2
It is also used as a spacer to fix 3.

In this gas-insulated electrical equipment, an internal corona is generated on the surface of the insulating spacer 24 between the conductor 23 and the container 20 due to insulation deterioration of the insulating spacer 24. Then, the current generated by the internal corona flows on the surface of the insulating spacer 24 and flows to the ground 25 via any one of the grounding wires 1a, 1b, and 1c+1d.

Here, the operation of the failure diagnosis apparatus main body 3 when an internal corona occurs will be explained based on FIGS. 2 to 4.

At this time, the equal circuit inside the gas-insulated electric equipment becomes as shown in FIG. 3. Cr indicates the equivalent insulation capacity of the insulating spacer 24, and R indicates the equivalent resistance value.

Assume that a current generated by the internal corona flows to the ground 25 via the grounding wire 1a. Then, assuming that the current generated by the internal corona is 1, the current 1 is shunted to each of the grounding wires 1b, 1c, and 1d via the ground 25. At this time, if the circuit breaker 22 is in an open state, the pair of ground wires 1a and 1b are connected to a point that cannot be separated in terms of the circuit, so the ground m 1 a, the ground 25°, and the ground wire 1b A closed circuit is formed between the conductor 23 and the conductor 23, as shown in the equivalent circuit of FIG.

As a result, a current of 11% in the opposite direction to the current I flowing through the grounding wire 1a flows through the grounding wire 1b. Therefore, the polarities of the outputs Sa and Sw from the pair of current sensors 2a and 2b are different. In addition, the grounding wires 1c and ld are
Since the circuit breaker 22 is open, no current flows.

As a result, the pair of current sensors 2a and 2b as shown in FIG.
Outputs SA and Sl+ having different polarities as shown in a) are applied to the fault diagnosis device main body 3.

It is now assumed that the contacts of the scanner circuit 8 of the main body 3 of the fault diagnosis device 3 on the signal lines A and B from the current sensors 2a and 2b are closed.

A pair of current sensors 2a added to the failure diagnosis device main body 3
, 2b, the outputs SA and Sl are as shown in FIG.
Via the scanner circuit 8 they are applied to amplifiers 9.10, respectively. Amplifier 9.10 receives outputs S from pair of current sensors 2a and 2b, and S through scanner circuit 8.
, respectively, to perform gain adjustment and amplify the outputs 3A1 and 3.1 with the same sensitivity as shown in FIG. 4(b).

And amplifier 9. lO applies the respective outputs 3.1 and 3.1 amplified to the same sensitivity to the pull means 4 and the polarity identification means 5, and at the same time to the multiplexer 15.

Here, the outputs SA' and S, l applied to the multiplexer 15 are sequentially applied to the analog-to-digital converter 16. Then, the analog-to-digital converter 16 is
Analog-to-digital conversion of the outputs SA', S, and l;
It is added to the determination means 7.

The determining means 7 monitors the magnitudes of the outputs SA' and SI' amplified by the digitally converted amplifiers 9.10, and determines the magnitudes of the outputs S,'' and S,I so that the maximum peak values of the respective outputs S,'' and S,I are equal. Then, the gain of amplifiers 9 and 10 is adjusted.As a result, the outputs SA' and S of amplifiers 9 and 10 are adjusted.
, l will be amplified to the same sensitivity.

Next, the subtraction means 4 subtracts the pair of outputs SA' and S, l of the same sensitivity input from the amplifiers 9 and 10. At this time, since the polarities of the outputs SA' and 3.1 are different, the outputs 5.1 and 3.1 have different polarities, as shown in FIG. 4(C). The current signal S (A-1
The magnitude of 11 is the sum of the absolute values of the respective magnitudes of the outputs SA, S, and l. Also, the current 11 and Ilb
Since the time during which the current flows through the current sensors la and ib is slightly different, the output S (A
-11 results in a slightly wider waveform. Further, the subtraction means 4 outputs the output S01. after performing the subtraction. is amplified to the maximum level at which the output of force means 4 does not saturate, and as shown in Fig. 4 (
The output S (A-ml') as shown in (b) is applied to the delay circuit 11.

The delay circuit 11 receives an output 5 (A
-11' for a certain period of time as shown in FIG. 4(e).

and is applied to the gate means 6.

On the other hand, the polarity identifying means 5 transfers the outputs SA' and 5.1 of the same sensitivity from the amplifiers 9 and 10 to the amplifier 1, respectively.
Waveform shaping is performed in steps 2 and 13.

Then, the AND circuit 14 outputs SA' of the amplifiers 9 and 10 whose waveforms have been shaped by the amplifiers 12 and 13, and the outputs SA' and 3. When the + polarities are the same, a prohibition output S as shown in FIG. 4(f) is applied to the gate means 6, which prohibits the output of the delay circuit 11 for a certain period of time. At this time, since the polarities of the outputs SA' and sl of the amplifiers 9 and 10 are different, the polarity identifying means 6
The inhibit output SL is not applied to the gate means 6 from the AND circuit 14. As a result, as shown in FIG. , the outputs S (A-ml') from the current sensors 2a, 2b due to the internal corona, .

The multiplexer 15 receives the output SA from the current sensors 2a and 2b due to the generation of internal corona.

Output S (A-ml
manually and sequentially added to the analog-to-digital converter 16. The analog-to-digital converter 16 is connected to the multiplexer 1
Output S (A-ml
′ is input and sequentially converted from analog to digital. Then, the analog-to-digital converter 16 applies the digitally converted output 5fA-□' to the determining means 7. The determining means 7 inputs the digitally converted output S (A-11') input from the analog-to-digital converter 16, and outputs the output S
(Compare the size of A-11' with a reference value and determine the number of occurrences of internal corona.

Further, the determining means 7 monitors the magnitude of this analog-to-digital converted output S (A-ml', and adjusts the pulling force so that the output S fA-11' of the pulling force means 4 reaches the maximum level at which it is not saturated. The gain of military means 4 is adjusted. As a result, the output S (
A-11' is applied from the delay means 4 to the delay circuit 11.

Next, a case where external noise arrives at the conductor 23 will be described.

Even when external noise arrives at the conductor 23 as indicated by the broken line N in FIG. 3, the conductor 23
A current generated by external noise flows through the surface of the insulating spacer 24 between the container 20 and the container 20 . Then, the current generated by external noise is transferred to the grounding wire 1a, as shown in FIG.
Flows from the conductor 23 toward the ground 25 as indicated by the broken line arrows lb and lb. At this time, the grounding wires 1a and l
Each of the currents flowing through b! If E and ■, then the current I
t and Is flow in the same direction. And ground wire 1
As currents [g, Is flow through a and 1b, outputs SMA and S□ of the same polarity as shown in FIG.
added to.

The failure diagnosis device main body 3 sends the output SNA and S□ through the scanner circuit 8 to the amplifier 9.10 with the same sensitivity as shown in FIG. The outputs are amplified to SNA' and S□'. The amplifiers 9 and 10 then output SM amplified to the same sensitivity.
A'*SNI' is applied to the output means 4, the polarity identification means 5 and the multiplexer 15. Next, the output S! applied to the multiplexer 15! 14' + SNI'
are respectively analog-to-digital converted by an analog-to-digital converter 16 via a multiplexer 15.

Then, the zero determination means 7, in which the digitally converted output SNA + SNI' from the analog-to-digital converter 16 is applied to the determination means 7, determines the magnitude of the outputs SNA', Ssm', as in the case of the internal corona described above. The amplifier 9. is monitored so that the maximum peak values of the output 5NAS□' are equal. Perform gain adjustment of IO.

Next, as in the case of the internal corona described above, the pulling means 4 also uses the output SMA which is amplified to the same sensitivity by the amplifier 9.10.
' and S□' are subtracted. At this time, the output S□'
and 311' have the same polarity, but because there is a slight time difference between the current I8 flowing through the grounding wire 1a and the current I flowing through the grounding wire tb, they are not completely subtracted;
The waveform S□A-111 shown in C) is obtained. moreover,
The pulling means 4 outputs the output SN (A-1
1 and output S N t as shown in FIG. 4(d).
A-1)'. Then, the pulling means 4 applies the amplified output S□A-11' to the delay circuit 11. The delay circuit 11 inputs the output S□A-□' of the pulling means 4, and as shown in FIG. 4(e), 1. The output 5NfA-□' delayed by time t2 is applied to the gate means 6.

On the other hand, the polarity identifying means 5 also receives the respective outputs S input from the amplifiers 9 and 10, as in the case of the internal corona described above.

' and S□' are waveform-shaped by amplifiers 12 and 13.

However, at this time, since the polarities of the outputs SHA' and stem' which have been waveform-shaped by the amplifiers 12 and 13 are the same, as described above, the AND circuit 14 of the polarity identifying means 5
For a certain period t, the gate means 6 outputs an inhibit output S as shown in FIG. 4(f).

is added. Thereby, the gate means 6 blocks the output S N tA-11' from the delay circuit 11 for a certain period of time. Moreover, the output S N (A-m
Since l is delayed by the delay circuit 11 for a time t5, the output S N (A-111') applied to the gate means 6 is
The signal enters within a certain period of the inhibition signal S, and is completely blocked. As a result, the current sensor 2a due to external noise.

The output SN fA-ml ′ processed by the puller means 4 of the output SHh+SNI from 2b is not applied to the multiplexer 15 and is not transmitted to the determination means 7.

Furthermore, the same operation is performed when the negative polarity output 5NAIISNII appears in the current sensors 2a and 2b due to external noise. 5NA1. shown in FIG. 4(a). S□1 is 5MAl' shown in FIG. 4(b), which shows the waveform when a negative polarity output appears in the current sensors 2a and 2b due to external noise.
+S%ml' is the output 5 of current sensors 2a and 2b.
NAI+SN□ shows the respective output waveforms amplified to the same sensitivity by amplifiers 9 and 10. SN (
□I11 is the respective output 5NA of amplifier 9.10
I'+SN□' represents the output waveform subtracted by the subtraction means 4. 5KI (^-II+
is the subtracted output 5N (A-111 is subtracted from the military means 4
S N shown in the same figure (e) showing the output waveform amplified by
tA-ml l' is the output S N (
A-111 shows the output waveform delayed by 1+ time in the delay circuit 11, and the SLI shown in FIG.
The waveform of the prohibition output applied from the polarity identifying means 5 to the gate means 6 when the output 5NAI' + 3□1' is manually input to the polarity identifying means 5 is shown.

In this way, the determination means 7 receives outputs S of the same polarity from the current sensors 2a and 2b generated by external noise. , S
□ or S. , 9 Output S□A-111' or S N fA-ml 1' processed by pulling means 4 of S□1
is not transmitted, and the current sensor 2a generated by the internal corona
, 2b with different polarities, and only the output S fA-ml ' processed by the Ss pulling means 4 is transmitted.

As a result, the occurrence of internal corona can be quantitatively evaluated without being affected by external noise, and the absolute amount of internal corona can be determined.

Furthermore, when internal corona occurs on the grounding wires 1c and ld, the scanner circuit 8 is connected to the current sensors 2a and 2b.
The same determination can be made by switching the signal lines A and B of the current sensors 2c and 2d to the signal lines C and D of the current sensors 2c and 2d.

In this embodiment, the case where the circuit breaker 22 is open has been described, but the determination can be made in the same way even when the circuit breaker 22 is closed.

〔Effect of the invention〕

The failure diagnosis device for gas-insulated electrical equipment of the present invention includes a pair of current sensors each attached to a pair of grounding wires connected to points that are not separated in terms of the circuit, and outputs from the current sensors being drawn and differentiated by military means. At the same time, the polarity discrimination means applies the output to the gate means when the polarity of the output of each current sensor is the same, that is, when there is external noise, and the gate means responds to the output of the polarity discrimination means to determine the output of the pull means. Since the output of the gate means is determined by the determination means, the occurrence of internal corona can be quantitatively evaluated without being affected by external noise, and the absolute amount of internal corona can be determined.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a schematic diagram showing the configuration of an embodiment of the present invention;
The figure is a block diagram showing the configuration of the main body of the failure diagnosis device shown in Figure 1, Figure 3 is an equivalent circuit diagram of the gas-insulated electrical equipment when internal corona occurs and external noise arrives, and Figure 4 is the second diagram.
A waveform diagram showing the waveform of the human output of each means in the figure, and FIG. 5 is a schematic diagram showing a part of a conventional failure diagnosis apparatus for gas-insulated electrical equipment. 1a to 1d...Grounding wire, 2a to 2d...Current sensor, 4...Subtraction means, 5...Polarity identification means, 6...
・Gate means, 7... Judgment means

Claims (1)

[Claims] A pair of current sensors each attached to a pair of ground wires connected to a point that is not separated from the circuit, a subtraction means for taking the difference between the outputs of the current sensors, and an output when the polarities of the outputs of the current sensors are the same. Fault diagnosis for gas insulated electrical equipment, comprising: polarity identification means for outputting the polarity identification means; gate means for blocking the output of the subtraction means in response to the output of the polarity identification means; and determination means for determining the output of the gate means. Device.