JP2543902B2 - Partial discharge detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a gas-insulated switchgear in which power equipment is compactly housed, and in particular, prevention suitable for confirmation and monitoring of the reliability of the housing equipment. The present invention relates to a partial discharge detection device used in a maintenance system.

(Prior art) In recent years, due to the need to strengthen substation equipment due to soaring land and increasing power supply in urban areas, SF ₆ gas, which has excellent insulation and extinction properties, has been used to The so-called gas-insulated switchgear, in which transformers such as circuit breakers are housed in a closed container and the environmental resistance and the installation volume per KV · A are made compact, has become widespread and in operation.

Although the gas insulated switchgear as described above has various advantages such as downsizing and reduction of the exposed charging part of the grounding tank, it is difficult to perform maintenance diagnosis due to high performance, and the maintenance and repair work time is increased. In the case where an abnormality occurs, there is a disadvantage that the reliability is significantly reduced.

Therefore, in order to improve the reliability of the entire gas insulated switchgear, we have been striving to properly design and manufacture the device. Confirmation and monitoring are required, and various effective means have been studied.

Problems at the present time will be described with reference to the layout diagram of the typical gas-insulated switchgear shown in FIG.

That is, as shown in FIG. 4, a lightning arrester 7, a transformer 8, a grounding switch 9, a disconnector 12, a current transformer 17,
A circuit breaker 18 and a bus bar 19 are provided, SF ₆ gas is filled as the filling gas 3, and the sealed pressure vessel 2 is at the grounding potential with the voltage applying section.
The spaces are electrically isolated.

Further, in order to arrange the bus bar 19 in the sealed pressure vessel 2,
Insulating spacers 11 are placed at appropriate intervals and
It is configured to be able to maintain the mechanical strength and dielectric strength.

Further, the main circuit is connected via the bushing 1 to the disconnector 12,
It is connected to a transformer 20 via a circuit breaker 18. In addition,
Although FIG. 4 shows a one-line power receiving main circuit,
From the main power receiving circuit not shown on the right side of FIG.
In some cases, power is supplied to the transformer 20 via the power supply.

On the other hand, the gas insulated switchgear is controlled by a switchboard 15, the voltage element is obtained by a transformer 8, the current element is obtained by a current transformer 17, and the main circuit switching and cutoff operation is performed by a switchgear via an operation cubicle 14. This is performed by giving an energizing signal to an operating device 13 of a similar type (disconnector, circuit breaker, ground switch).

Further, as a mechanical drive source for the switches, a predetermined pressure (generally 15 kg / cm ² for example) is obtained by the compressor equipment 16 and supplied to the operating device 13 via the operating cubicle 14.

On the other hand, since the insulating spacer 11 also has a function of enclosing the filled gas from the viewpoint of separation for maintenance and the arrangement configuration, the insulating spacer 11 is connected to each of the SF ₆ gas cylinder 6 and the gas cubicle 5 via the valve 4. Fill the compartment with SF ₆ gas,
The gas cubicle 5 also makes the pressure visible.

In the conventional gas-insulated switchgear having the above-mentioned configuration, the storage device can be downsized due to the characteristics of SF ₆ gas, and the overall downsizing can be realized.
(The occupying volume per KV / A becomes small, and the effective use of the installation site can be achieved.) In addition, it is possible to construct a stack of 2 to 3 tiers using gas busbars, and block laying is possible, so a small area is required. There was an advantage that a large volume structure could be taken.

Furthermore, since the sealed pressure vessel is grounded, there is no danger of electric shock even when approaching during power application, and the power application unit is not directly exposed to environmental disturbances caused by salt damage, wind and rain, etc. It is not affected.

Further, since various switches are subjected to arc treatment in SF ₆ gas having a high extinguishing ability, there is also an advantage that the breaking capacity per main contact can be greatly improved.

On the other hand, while it has the advantages as described above, it has the following drawbacks.

In other words, by making the entire gas-insulated switchgear compact, the size restrictions of dismantling work or reassembly work are reduced during maintenance / inspection of storage equipment, which requires time for maintenance / inspection work and significantly reduces work efficiency. Was there.

In addition, the SF ₆ gas filled in the container is expensive, the manufacturing technology for preventing gas leakage to the outside is high-grade, and since the kv / mm is large due to its good insulating property, the decrease in gas pressure causes insulation margin It was urgent to repair gas leaks.

Further, since the sealed pressure vessel is used, there is a problem that the storage device cannot be visually monitored.

Also, replacement work due to exhaustion of the main contacts of various switchgear requires a great deal of time for SF ₆ gas recovery and refilling work.
There is also a drawback that the gas insulation switchgear has a long down time.

In contrast to the advantages and disadvantages described above, the advantages are large in terms of performance, so the spread of gas insulated switchgear is remarkable, but when the number of installation locations increases and mass production system can be adopted, its maintenance and The preparation of the emergency repair system and the variation in quality are also issues that cannot be ignored.

As a countermeasure, it is earnestly desired to establish a preventive maintenance system capable of confirming the reliability that the operating condition is normal and capable of early detection and monitoring when an abnormality occurs.

Expected effects of such a preventive maintenance system will be described with reference to FIG.

That is, FIG. 5 is a potential deterioration failure model diagram in which the vertical axis represents the potential characteristic L of the sample and the horizontal axis represents the elapsed time t. In the process of becoming a phenomenon as an accident, it progresses at an accelerated rate at point f and reaches an accident phenomenon with no time margin. Therefore, it is desirable to detect an abnormality in the warning area B at points a to e.

The reason is that various abnormalities develop physically over a long period of time, and even if abnormalities are confirmed, direct emergency measures such as an emergency stop are not required, and it is possible to obtain from the repair margin time by voluntary stop. Then, there is no accident expansion phenomenon such as primary and secondary damage at the time of the accident phenomenon, and the repaired area can be limited to the minimum necessary area.

Therefore, it is important to select the parameter detection level,
The point is to monitor items based on the fault tree analysis specific to the sample.

These monitoring items include the amount of corona, the amount of gas moisture, the gas component, the gas pressure, which the measured value itself does not change rapidly.
It requires quasi-stationary items such as gas temperature, gas density, oil level, oil pressure, oil temperature, amount of decomposed gas, etc., and processing within a short time, such as the operating time of the circuit breaker, disconnector, etc. There is an item.

As for the usual monitoring method, for the latter item,
When the equipment is operating, measurement is performed, data is processed and calculated, and the results are output, displayed, and stored.For the former quasi-stationary item, measurement is performed at certain fixed time intervals and data is processed and calculated. , The result is output, displayed and stored.

Among such monitoring items, detection of partial discharge (corona detection) is one of the most important ones from the viewpoint of predicting device abnormality.

However, regarding the detection of such partial discharge,
Although more detection devices have been proposed than in the past, a rational configuration for applying these to actual devices has not yet been established.

(Problems to be Solved by the Invention) As described above, in the conventional gas-insulated switchgear, a device for detecting a partial discharge generated inside the device has not been realized.

Therefore, the present invention has been proposed in order to eliminate the above drawbacks, and an object thereof is to provide a partial discharge detection device capable of efficiently detecting a partial discharge generated inside the equipment of a gas insulated switchgear. Especially.

[Structure of the Invention] (Means for Solving the Problems) The present invention relates to a gas-insulated switchgear configured by a plurality of gas-insulated devices in which a high-voltage conductor is housed in a grounded metal container together with an insulating gas. An apparatus for detecting a partial discharge generated inside is characterized in that a partial discharge detection means capable of detecting an electromagnetic wave is provided in the vicinity of an external connection portion between a gas insulation device and a power cable or the like.

(Operation) In the partial discharge detection device of the present invention, since there is an insulating portion in the external connection portion such as the cable head,
By utilizing the point that the shield is broken at this portion and the electromagnetic wave also leaks to the outside, the electromagnetic wave can be efficiently detected from the outside of the gas insulated switchgear by installing the detection means at this portion.

The partial discharge that occurs in each gas-insulated switchgear equipment is related to the discharge phenomenon of SF ₆ gas, and the resulting signal becomes a very high-frequency electromagnetic wave. Then, this electromagnetic wave leaks to the outside by breaking the shield in the vicinity of the external connection portion such as a cable head having an insulating portion,
It is detected by the partial discharge detection device of the present invention arranged outside the gas insulated switchgear.

Note that the external connection that connects the gas-insulated equipment to other equipment corresponds to the end of the GIS, and the gas-insulated equipment is placed only on one side of the external connection, so the electromagnetic waves on the line are It is propagated from one direction to the connection, that is, only from the GIS side.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 3. The same members as those of the conventional type shown in FIGS. 4 and 5 are designated by the same reference numerals, and the description thereof will be omitted.

* Structure of Embodiment * In this embodiment, as shown in FIGS. 1 and 2, an electromagnetic wave detector 50, which is a partial discharge detection means, is provided in the vicinity of an external connection between a gas-insulated device and a power cable or the like. It is arranged.

That is, the general equipment layout of the gas insulated switchgear is such that the main bus 31 is connected to the disconnector 32, the disconnector 32 is connected to the circuit breaker 33, and further, the disconnector is connected via the current transformer 40. 34,
A grounding device 35 is connected and is drawn out to the outside via an instrument transformer 41 and a cable head 36. An insulating tube 42 is arranged at the connection between the cable head 36 and the power cable 43, and an electromagnetic wave detector 50 is arranged in the vicinity thereof.

The electromagnetic wave detector 50 is, for example, a third
The one shown in the figure is used. That is, the filter 52 is connected to the loop antenna 51 that detects electromagnetic waves, and is further connected to the optical cable 57 via the amplification circuit 53, the peak detector integration circuit 54, and the E / O converter 55.

* Operation of Embodiment * The partial discharge detection system of this embodiment having such a structure operates as follows.

That is, in general, the partial discharge that occurs inside the gas-insulated equipment is related to the discharge phenomenon of SF ₆ gas, which has a rise of several ns, so the signal generated by it is also an electromagnetic wave that extends from several tens of MHz to several GHz. Become. In this way, the electromagnetic waves generated by the internal partial discharge of the equipment are extremely high frequency, so the gas-insulated equipment itself plays the role of a kind of waveguide,
Since the electromagnetic wave propagates in the grounded metal container, the presence or absence of partial discharge inside the device can be determined by detecting such an electric wave signal.

However, since the high-voltage charging part of the gas-insulated equipment is completely covered by the grounded metal container, the electromagnetic waves as described above do not go out, but in the external connection part such as the cable head,
Since there is an insulating portion such as an insulating cylinder provided between the grounded metal container and the power cable, the shielding is broken, and electromagnetic waves also leak to the outside. This is because if the grounded metal container of the gas-insulated device has an insulating portion, electromagnetic waves leak to the outside due to the ratio of the internal impedance of the gas-insulated device, the impedance of the insulating cylinder, and the external impedance of the grounded metal container. .

Therefore, as shown in the present embodiment, by disposing the electromagnetic wave detector in such an external connection portion, it is possible to immediately detect the partial discharge generated inside the gas insulated device.

In addition, if an electromagnetic wave detector is installed at the external connection of each line of the gas-insulated equipment, it is possible to monitor internal abnormalities on a line-by-line basis. Good and efficient maintenance and inspection work.

Further, if the electromagnetic wave detector as described above is installed in the external connection part of each line, all the charging parts of that line can be monitored, and the number of detectors to be installed can be greatly reduced. .

* Other Examples * Note that the present invention is not limited to the above-described examples, and the shielding of the grounded metal container as described above is broken in the air bushing portion as in the cable head portion.
Even if a similar electromagnetic wave detector is provided near the air bushig part, the partial discharge generated inside the device can be efficiently detected.

Further, the partial discharge detection device as described above, when the gas insulation device is installed in the rebar building, or in the basement,
Especially effective. This is because in the rebar building and basement, they play a role as a kind of shielded room, compared to the atmosphere where there are many external noises such as broadcast radio waves.
External noise can be significantly reduced, and accurate internal partial discharge can be monitored.

[Advantages of the Invention] As described above, according to the present invention, a partial discharge detection means such as an electromagnetic wave detector is provided in the vicinity of an external connection portion between a gas insulated device housed in a grounded metal container and a power cable or the like. It is possible to provide a partial discharge detection device capable of efficiently detecting the partial discharge generated inside the equipment of the gas insulated switchgear by a simple means of disposing.

That is, the external connection portion connects the gas-insulated device and another device, and corresponds to the end of the GIS, and the gas-insulated device is arranged only on one side. Therefore, the electromagnetic waves due to the partial discharge generated in the line in which the partial discharge detecting means of the present invention is installed are propagated only from the GIS side to the external connection portion. Therefore, there is an effect that there is no deviation in the direction of the electromagnetic wave detected by the present invention.

Further, the electromagnetic waves generated in the adjacent line are attenuated in the propagation process until reaching the vicinity of the partial discharge detecting means arranged in the vicinity of the external connection portion of the present invention, so the partial discharge detecting means of the present invention Can detect the electromagnetic wave generated in the line efficiently and accurately.

Furthermore, since the partial discharge detection device of the present invention only needs to be arranged in the vicinity of the external connection portion for each line, the number of partial discharge detection devices to be arranged can be greatly reduced.

[Brief description of drawings]

FIG. 1 and FIG. 2 are arrangement layout diagrams of equipment showing an embodiment of the partial discharge detection device of the present invention, and FIG. 3 is a configuration diagram showing an example of a detector used in the partial discharge detection device of the present invention. , FIG. 4 is a layout configuration diagram of a general gas insulated switchgear, and FIG. 5 is a conceptual diagram showing an effect of the preventive maintenance system. 1 ... Bushing, 2 ... Sealed pressure vessel, 3 ... Filling gas, 4 ... Valve, 5 ... Gas cubicle, 6 ... Gas cylinder, 7 ... Lightning arrester, 8 ... Transformer, 9 ... Grounding open / close Switch, 11 ... Insulating spacer, 12 ... Disconnector, 13 ... Operator, 14 ... Cubicle, 15 ... Switchboard, 16 ... Compressor equipment, 17 ... Current transformer, 18 ... Circuit breaker, 19 ...... Bus, 20 ...... Transformer, 31 ...... Main bus, 32 ...... Disconnector, 33 ...
… Circuit breaker, 34… Disconnector, 35… Grounding device, 36… Cable head, 40… Current transformer, 41… Instrument transformer, 42…
… Insulation cylinder, 43 …… Power cable, 50 …… Electromagnetic wave detector.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-61-167880 (JP, A) JP-A-55-27903 (JP, A) JP-A-49-46780 (JP, A) JP-A-59- 139815 (JP, A) Actually open 55-51775 (JP, U) Actually open 59-117038 (JP, U) Japanese public Sho 58-30555 (JP, B2) Japanese public Sho 60-16163 (JP, B2)

Claims (3)

(57) [Claims] 1. A device for detecting a partial discharge generated inside a gas-insulated switchgear constituted by a plurality of gas-insulated equipment, which comprises a high-voltage conductor and an insulating gas housed in a grounded metal container. A partial discharge detection device comprising a partial discharge detection means capable of detecting an electromagnetic wave in the vicinity of an external connection portion between a gas insulation device and an electric power cable or the like. 2. The partial discharge detection device according to claim 1, wherein the gas-insulated switchgear is installed in a rebar building or a basement. 3. The partial discharge detection device according to claim 1 or 2, wherein the partial discharge detection means is provided with a detection antenna.