JPH04136771A - Method for detecting internal partial discharge of gas insulated switchgear - Google Patents

Abstract

PURPOSE:To efficiently locate a trouble place with high accuracy by using a reduced number of detectors usually to perform on-line monitor by properly using detection frequency. CONSTITUTION:When a disconnector 5 on a line side and a disconnector 2A on a bus side are opened in a circuit I, the usual line and main bus 1A of the circuit I are stopped and regions B, D to be monitored are charged through a main bus 1B. Since it is necessary to monitor the partial discharge in both regions B, D to be monitored, the partial discharge detectors 13B, 13D in the respective regions B, D are used to monitor the regions B, D and partial discharge can be detected. By this method, when partial discharge is usually monitored on-line, partial discharge can be efficiently monitored by using only the partial discharge detector of a necessary region.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to an internal partial discharge detection method applied to a gas-insulated switchgear in which power equipment is compactly housed in a grounded metal container.

(Prior Art) In recent years, gas insulated switchgear (GIS) has become popular and in operation due to the need to strengthen substation equipment due to the soaring cost of land for power plants and the increase in the amount of power supplied in urban areas. As is well known, this gas-insulated switchgear has a disconnector, circuit breaker, etc. housed in a sealed container, and its surroundings are filled with SF6 gas, which has excellent insulation and arc-extinguishing properties, to ensure insulation. There is.

Such a gas insulated switchgear has various advantages such as being compact and reducing the number of exposed live parts in the grounded tank. However, on the other hand, it has the drawback that reliability is significantly reduced if an abnormality occurs inside the sealed container due to the difficulty of maintenance diagnosis and increased time required for maintenance and repair work as the performance increases.

Therefore, gas-insulated switchgear equipment includes a substation equipment control system that issues circuit breakers, disconnectors, and earthing switches, exception commands, etc., and a system that confirms the reliability of the normal operating status of substation equipment. It is equipped with a preventive maintenance system that enables early detection and monitoring in the event of an abnormality.

The latter preventive maintenance system monitors items such as corona amount, gas moisture content, gas composition, gas pressure, gas temperature, gas density, oil level, oil pressure, oil temperature, and cracked gas amount, whose measured values do not change rapidly. There are items that are quasi-stationary, such as, and items that require processing within a short time, such as the operating time of circuit breakers and disconnectors. The normal monitoring method is to measure the latter item while the equipment is operating, process and calculate the data, and output and display and store the results.For the former quasi-stationary item, the measurement is performed at certain intervals of time. It measures the data, processes and calculates the data, and outputs, displays, and stores the results.

(Problems to be Solved by the Invention) Among such monitoring items, partial discharge detection (corona detection) is one of the most important items from the viewpoint of predicting equipment abnormalities. Regarding partial discharge detection, many detection methods have been proposed in the past, or when these methods are systematically applied to actual equipment, there are problems especially with regard to the location of the defective location. .

That is, in the conventional partial discharge detection method, it is difficult to locate the defective location when an abnormality occurs. In order to perform such orientation with the highest possible precision, detectors are placed at many locations on the gas-insulated switchgear.
Since this large number of detectors must be used for constant monitoring, there is a drawback that efficiency is low and economical efficiency is low.

The present invention was proposed to solve the problems of the prior art as described above, and its purpose is to perform online monitoring using a small number of detectors at all times, and to locate the defective location when an abnormality occurs. An object of the present invention is to provide an excellent method for detecting internal partial discharge in a gas-insulated switchgear, which enables highly accurate and efficient detection of internal partial discharge.

[Structure of the Invention] (Means for Solving the Problems) The present invention is directed to the propagation characteristics of high-frequency components among the propagation characteristics in a grounded metal container of partial discharge pulses generated due to internal partial discharge of gas-insulated equipment. This proposal focused on the fact that the propagation characteristics of low-frequency components are local, and the propagation characteristics of low-frequency components are local.

That is, the internal partial discharge detection method of the gas insulated switchgear of the present invention is a gas insulated switchgear in which various devices including a high voltage conductor, a circuit breaker, and a disconnector are connected and housed together with an insulating gas in a grounded metal container. In a method for detecting internal partial discharge in switchgear, internal partial discharge is detected using an electrode buried in an insulating spacer or other internal electrode arranged in a grounded metal container, and partial discharge is constantly monitored online. In case, a detector with a detection frequency in a predetermined range is used, and in case of regular or occasional off-line measurements, a detector with a detection frequency lower than in the above case is used.
It is characterized by the use of at least one type.

Especially when monitoring partial discharge online all the time,
It is desirable to use a detector with a frequency of MHz or higher, and to use a detector with a frequency of IM Hz or lower when performing regular or occasional off-line measurements.

(Operation) In the method of the present invention having the above configuration, when monitoring partial discharges online at all times, a detector having a detection frequency in a predetermined high range is used to detect propagation characteristics over a wide range. The high frequency component of a certain partial discharge pulse is monitored, and the occurrence of partial discharge can be detected by detecting this high frequency component. When such an abnormality occurs, off-line, a detector with a detection frequency in a low range is used to monitor the low frequency component of the partial discharge pulse, which has local propagation characteristics, and detect the problem with high precision. The location can be located.

Therefore, it is sufficient to use a small number of detectors for constant online monitoring, and to use the necessary number of detectors only when an abnormality occurs, so that partial discharge can be monitored efficiently. In this case, especially when an abnormality occurs, the portable measuring device can be used to locate the defective location with high precision.

(Example) Hereinafter, an example of the internal partial discharge detection method for a gas insulated switchgear according to the present invention will be specifically described with reference to FIGS. 1 and 2.

First, FIG. 1 shows the detector arrangement during online monitoring. In this Fig. 1, the target gas insulated switchgear has three lines I, n, m from parallel main buses IA and IB.
This is the configuration when . Furthermore, these three lines I,
Since the connected equipment configurations of II and H are the same, only the representative line I will be explained below, and the other lines ■ and ■
The same reference numerals will be used for the explanations.

Line I is configured as follows. That is, both busbars IA and IB are each pulled out and connected to the busbar side disconnector 2A.
, 2B, and the busbar side disconnectors 2A, 2B
The other ends are connected in common and connected to one terminal of the circuit breaker 3. An earthing switch 4 is connected to the earth E between this circuit breaker 3 and a common connection point of the disconnectors 2A and 2B. The other terminal of the circuit breaker 3 is connected to the track side disconnector 5
is connected to the cable head 6 via the track side disconnector 5.
A grounding switch 7 is connected between the cable head 6 and the ground E.

Furthermore, these busbar side disconnectors 2A, 2B, circuit breaker 3,
The grounding switch 4, line-side disconnector 5, cable head 6, and grounding switch 7 are housed in a row in a metal container 8 at ground potential (grounded metal container), and insulating spacers 9A, 9B,
IOA, IOB, 11°12, bus side disconnector 2A,
2B, the circuit breaker 3, and the line-side disconnector 5 are separated from each other by gas.

In addition, in reality, a large number of insulating spacers are used in addition to the above, but in FIG. 1, for convenience, only the insulating spacers on which the partial discharge detector is installed are shown.

Then, as shown in Fig. 1, the above main bus line IA
, lb to the cable head 6 is roughly divided into four monitoring target areas A, B, C, and D, and each monitoring target area A-D is indicated by a broken line. They are shown as enclosed and separated parts. That is, a portion including the cable head 6, the grounding switch 7, the insulating spacer 12, and the line-side disconnector 5 is classified as the monitoring target area A; 4. Insulating spacer IOA,
The area including the IOB and bus-side disconnectors 2A and 2B is classified as a monitoring target area B, and the area including the bus-side disconnector 2A, insulating spacer 9A, and main bus IA is classified as a monitoring target area C. Disconnector 2B, insulation spacer 9
A portion including the main bus line IB and the main bus line IB is classified as a monitoring target area.

Furthermore, in FIG. 1, at least one insulating spacer 12 in each of the monitored areas A, B, C, and D
, 11.9A, 9B, partial discharge detectors 13A, 13B
, 13C, and 13D are connected to each other. These partial discharge detectors 13A to 13D, as shown in FIG.
It is connected to the. These partial discharge detectors 13A-1
Since the 3D circuit configuration is the same, only the partial discharge detector 13A of the monitoring target area A will be described below as a representative with reference to FIG.

As shown in FIG. 2, the insulating spacer 12 separates the gas inside the grounded metal container 8 in the monitored area A of FIG. Supports insulation.

The partial discharge detector 13A connected to the buried electrode 14 of the insulating spacer 12 includes a filter 16 connected between the buried electrode 14 and the ground potential of the grounded metal container 8, and a detection amplifier circuit 1.
7. Peak detector/integrator circuit 18, A/D converter 1
9, an E10 converter 20, a battery 21, and a timer 22. The partial discharge detection signal detected by the filter 16, the detection amplifier circuit 17, and the peak detector/integrator circuit 18 is converted into a digital signal by the A/D converter 19. The signal is converted into an optical signal by an E10 converter 20, and then transmitted to the receiving side via an optical cable 23.

This example uses the detector configuration described above to monitor and detect internal partial discharges. Specifically, it detects electromagnetic waves accompanying internal partial discharges in gas-insulated equipment to detect partial discharges. This is to determine the presence or absence. The detection of this electromagnetic wave will be explained below.

First, internal partial discharge in gas-insulated equipment is related to the SF6 gas discharge phenomenon whose rise time is several nanoseconds, so the signal generated thereby is an electromagnetic wave with an extremely high frequency of up to several hundred MHz. In this case, the live parts of the gas-insulated equipment are housed in the grounded metal container 8, so electromagnetic waves with a frequency of several MH or higher due to internal partial discharge generated in the grounded metal container 8 are prevented from being grounded. The metal container 8 will act as a waveguide. Therefore, the signal generated by the partial discharge propagates within the grounded metal container 8. Therefore, by detecting such electromagnetic wave signals, it is possible to determine the presence or absence of partial discharge, and in this embodiment, the presence or absence of partial discharge can be determined by detecting such electromagnetic wave signals. be.

That is, electromagnetic waves associated with partial discharge propagate within the grounded metal container 8, but when the circuit breaker 3, bus-side disconnectors 2A, 2B, line-side disconnector 5, etc. open, the electrical connection of the main circuit section is interrupted. , the electromagnetic waves are significantly attenuated at this open circuit point. Therefore, it is necessary to measure the partial discharge by dividing the area to be monitored based on the placement locations of these switching devices.

The above-mentioned monitoring target areas A-D are divided for this reason, and as mentioned above, each monitoring target area A-D
are shown as separate parts, each surrounded by a dashed line.

Next, a specific method for detecting electromagnetic wave signals will be explained.

For example, in line I in FIG. 1, if the line-side disconnect switch 5 is open and the bus-side disconnect switch 2A is open, the normal line and main bus IA of line I are stopped, and the monitoring target area B,
D is charged through the main bus IB. Therefore, both monitoring target areas B.

Since partial discharge monitoring in D is necessary, each area B,
Partial discharge detectors 13B and 13D in D can be used to monitor areas B and D, respectively, and detect partial discharges.

In another case, when inspecting the circuit breaker 3 while the line of the line I and the bidirectional buses IA and IB are charged, the circuit breaker 3 is opened and only the monitored area B is stopped. Therefore, it is necessary to measure partial discharge in the other three monitoring target areas A, C, and D.
Partial discharge detectors 13A, 13C, and 13D in D can be used to monitor the respective areas A, C, and D to detect partial discharges.

As described above, in this embodiment, when partial discharge is constantly monitored online, partial discharge monitoring can be carried out efficiently by using only the partial discharge detectors in the necessary areas.

As shown in Figure 1, the other lines ■ and ■ are also monitored in the four monitoring areas A with the switching equipment as the reference, just like the line workers.
Therefore, partial discharge monitoring can be performed efficiently on the other lines (1) and (2) in the same manner as described above regarding the line I.

Normally, when performing partial discharge monitoring, airborne noise including broadcast radio waves, etc.
They can enter the monitored area from the power supply, etc., and have a major impact on measurement accuracy. On the other hand, if gas-insulated switchgear is installed in a reinforced concrete building or basement, the indoor area is equivalently shielded from airborne noise, so the effects of airborne noise are significantly reduced. be done.

Therefore, for gas-insulated switchgear installed in such reinforced concrete buildings or basements, if the monitoring target areas are divided as shown in Figure 1 and internal partial discharge is monitored individually for each area A-D. can perform highly accurate measurements.

By the way, as shown in FIG. 1, the partial discharge detectors 13A~
It is difficult to accurately locate the abnormal location just by placing 13D. That is, in FIG. 1, if all the main circuits are connected, the partial discharge detector 13 in the monitoring target area A
If A detects an abnormality, it may be possible to determine that the abnormality is at least in that area A, but it is difficult to locate the exact location of the abnormality within that area A. This is because the gas-insulated switchgear acts as a distributed constant circuit for partial discharge signals of several MHz or more, so partial discharge signals of several MHz or more propagate with almost no attenuation, and are not detected even in 13C113D. This is because there is a large possibility that Therefore, when a detection band of several MHz or more is used, it is possible to efficiently detect the presence or absence of an abnormality with a small number of detectors, but it is difficult to locate the abnormal location.

Generally, a partial discharge signal propagates at a high speed of about 300 m/μm. When the wavelength λ of the partial discharge signal and the spread (Lm) of the gas-insulated switchgear become comparable, the gas-insulated switchgear can be regarded as a lumped constant. Here, Lm100m
Then, LL, λ= (300X106)/f=100mf-3
X10” Hz=3MHz.

On the other hand, since the partial discharge signal also includes a low frequency signal of IMHz or less, the gas insulated switchgear can be regarded as a lumped constant for signals in this frequency band as described above. Therefore, the propagation characteristics inside the gas-insulated switchgear of such a partial discharge signal in a low frequency band are significantly different from those of a high frequency component.

FIG. 3 shows an equivalent circuit of FIG. 2, in which reference numerals 51-53 indicate partial discharge pulse generation sources, and C1 to C3 indicate capacitive loads. Now, a partial discharge S1 occurs on the high voltage conductor 15.
For low frequency components of IMHz or lower, which occur between the power supply and the grounded metal container 8, the gas insulated switchgear can be regarded as a capacitive load C3 in addition to the lumped constant. In normal substations, this C3 is large, ranging from several thousand to pF, so this C3
81 is almost absorbed by 3, and insulating spacer 1
No signal appears on the buried electrode 14 in 2.

On the other hand, partial discharge s2 in FIG. Regarding s3, as can be seen from the circuit configuration, low frequency components can also be detected from the buried electrode 14.

The above shows that partial discharges occurring particularly near the insulating spacer 12 can be detected with high sensitivity by measuring only low frequency components below IMHz. In other words, as mentioned above, when a detection band of several MHz or more is used, the presence or absence of an abnormality can be detected efficiently with a small number of detectors, but on the other hand, it is difficult to locate the abnormal location. By using the detection band, it is possible to easily locate the abnormal location.

Therefore, the high frequency band is usually monitored online using a small number of detectors, and only when an abnormality is detected in the entire gas-insulated switchgear or a part of it, the insulating spacer in the relevant area is monitored offline. By measuring the low frequency components of the discharge, the defective location can be located with high precision and efficiency.

Furthermore, the buried electrode 14 used in this example is
Since it is necessary in the insulation design to alleviate the concentration of the electric field on the ground side, it is usually provided in each insulating spacer 12, and since it is used as it is, there is also the advantage that the device configuration is simple. .

Note that the present invention is not limited to the above-mentioned embodiments, and, for example, the specific configuration of the partial discharge detector can be selected as appropriate. The placement location can also be freely selected.

Furthermore, the internal electrodes used for detection can be provided separately from the embedded electrodes in the insulating spacer.

Furthermore, the present invention is equally applicable to gas-insulated switchgear of any arrangement, and can be similarly efficiently installed by appropriately arranging partial discharge detectors according to the specific arrangement. It is possible to perform partial discharge detection.

[Effects of the Invention] As explained above, in the present invention, by using different detection frequencies, online monitoring is performed using a small number of detectors at all times, and when an abnormality occurs, it is possible to locate the defective location, which was difficult in the past. It is possible to provide an excellent method for detecting internal partial discharge in a gas-insulated switchgear that enables highly accurate and efficient location.

[Brief explanation of the drawing]

FIG. 1 is a single line diagram of a gas insulated switchgear showing an embodiment of the internal partial discharge detection method of the gas insulated switchgear according to the present invention, and FIG. 2 shows the circuit configuration of the partial discharge detector of FIG. 1. The circuit diagram shown in FIG. 3 is an equivalent circuit diagram of FIG. 2. i, n, m...line, IA, IB...main bus line,
2A. 2B... Busbar side disconnector, 3... Circuit breaker, 4... Earthing switch, 5... Track side disconnector, 6... Cable head, 7 Earthing switch 1.8... Grounded metal container, 9A,
9B. 10A, IOB, 11.12... Insulating spacer, 13
A, 13B, 13C, 13D...partial discharge detector, A
, B, C, D...areas to be monitored. 14... Buried electrode, 15... High voltage conductor, 16...
・Filter, 17...Detection amplifier circuit, 18...Peak detector/integrator circuit, 1...A/D converter, 2
0...E10 converter, 21...battery, 22...
Timer, 23...optical cable. sl, s2. s3...Generation source of partial discharge pulse, cl
, c2. c3...capacitive load. Diagram

Claims (2)

[Claims] (1) In a method for detecting internal partial discharge in gas-insulated switchgear in which various devices including high-voltage conductors, circuit breakers, and disconnectors are connected and housed together with insulating gas in a grounded metal container, A detector with a detection frequency within a defined range, if the detection is carried out using a buried electrode in an insulated spacer or other internal electrode arranged in a grounded metal container, and if partial discharge is monitored on-line at all times. internal partial discharge of gas-insulated switchgear, characterized in that when measuring regularly or temporarily off-line, at least one type of detector having a detection frequency lower than that in the above-mentioned case is used. Detection method. (2) If you want to monitor partial discharge online all the time, 5
The interior of the gas insulated switchgear according to claim 1, characterized in that a detector with a frequency of MHz or more is used, and a detector with a frequency of 1 MHz or less is used for regular or temporary off-line measurements. Partial discharge detection method.