JPH03243872A - Ground fault point detecting method for gas insulation opening and closing device - Google Patents

Abstract

PURPOSE:To speedily and accurately specify an accident occurrence position without making a patrol by impressing a voltage to an area where the gas insulation opening and closing device(GIS) is stopped from operating because of the presence of a ground fault point, and deciding the ground fault point. CONSTITUTION:For example, a ground fault accident occurs in a section 16 of the GIS which is sectioned with insulating spacers 10 and 11. A generated arc moves fast in the GIS along a conductor and stops at the spacer 11 and the arc stays at the insulating space part until a ground fault current is cut off. Breakers 1 - 4 are tripped under the command of a protection relay and a thick-line part is disconnected from the system. In this state, an AC power source 17 is connected to the secondary side 8a of a gas PT (gas insulation voltage transformer) 8 for an A type bus to excite the PT 8 reversely and when an AC voltage is impressed to the stop range of the thick-line part, partial discharger is caused at the spacer 11 which is damaged by the arc at the time of the ground fault because of an AC voltage generated by the reverse excitation. A high frequency pulse voltage which is induced owing to the partial discharge is detected by the buried electrode of the insulating spacer. Further, the damage insulating spacer is specified.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a gas-insulated system installed in an electric station (power station, switchyard, substation, etc.) for transmitting and receiving electric power. Switchgear (hereinafter referred to as
The present invention relates to a method for detecting a ground fault point that occurs in a GIS.

(Prior art) Since the live parts of GIS are housed in a metal container, even if a ground fault occurs, as long as the container is not damaged, it is not possible to find the ground fault point from the outside1-13. Have difficulty. In addition, even if a container is damaged, GIS is installed over a wide area, and pipe-shaped containers are arranged in a complicated manner, so it will take a considerable amount of time to find the damaged location. It takes. Therefore, from the perspective of speeding up accident recovery and saving labor, a method for detecting ground fault points using various inserted sensors has been proposed so that operators and maintenance personnel can identify ground fault points without having to patrol the electrical station. has been done. Each method will be explained below.

(a) Grounding wire current detection method When a grounding fault occurs inside the GIS, the grounding current is G
Since this current flows through the grounding wire of the IS, this grounding current is detected using a current transformer provided for each grounding wire, thereby identifying the location where the grounding fault has occurred. However, since the ground fault current is divided into a plurality of grounding wires, it is necessary to understand in advance the branch current situation for all possible ground fault points.

(b) Impact gas pressure rise detection method The first wave of pressure rise due to arc energy during a ground fault inside the GIS is detected by a pressure sensor installed in each gas section at the location where the ground fault occurred. This is a method of identifying However, in devices that interrupt fault current, such as circuit breakers, it is difficult to distinguish between a pressure rise at the time of a ground fault and a pressure rise at the time of current cutoff using a pressure sensor.

(C) Vibration acceleration detection method This method detects the vibration acceleration of the container due to arc energy during a GIS internal ground fault with an acceleration sensor placed on the wall of the container to identify the ground fault occurrence area (1°L). However, in devices that have moving parts, such as circuit breakers, disconnectors, and grounding switchgears, there is a possibility that the acceleration sensor will erroneously identify vibrations during operation as vibrations caused by ground faults.

(d) Arc light detection method This is a method in which the arc light at the time of a ground fault is detected by an optical sensor such as a photodiode through a condensing window placed in a through hole of the container, and the location of the ground fault is identified. be. However, with this method, it is difficult to distinguish between light emitted by normal current switching and arc light at the time of an accident in circuit breakers, disconnectors, earthing switchgears, etc. that switch current.

(Problems to be Solved by the Invention) As described above, each of the four methods for detecting a ground fault point has its own problems. That is, in the (a) grounding line current detection method, since the ground fault current is divided into a plurality of grounding lines, it is necessary to know the nature of the branching in advance. In other words, by injecting a current into an assumed ground fault point and measuring the current flowing through each ground wire at this time, it is possible to know the current situation.

Therefore, it is necessary to install the GIS on-site.
It is difficult to grasp the accurate current distribution, and GIS
If a ground fault is added, the current distribution will change, resulting in inconveniences such as the need to change the criteria for determining where a ground fault has occurred.

In addition, (b) impact gas pressure rise detection method, (c) vibration acceleration detection method, and (d) arc light detection method are all applicable to circuit breakers, disconnectors, and grounding switchgears. There is a strong possibility that the phenomena at the time of a ground fault are the same, and there is a problem with the reliability of identifying the location where a ground fault has occurred using a single detection method.

In addition, (b) the impact gas pressure 1'' detection method and (d) the arc light detection method require a through hole for a sensor to be provided in the container, which has the disadvantage of impairing the reliability of the GIS against gas leakage.

The present invention was proposed to solve the following problems, and its purpose is to
An object of the present invention is to provide a method for detecting a ground fault point in a gas insulated switchgear, which allows an operator or a maintenance person to quickly and accurately identify the location of an accident without having to patrol around G13.

[Structure of the Invention] (Means for Solving the Problems) A method for detecting a ground fault point in a gas insulated switchgear according to the present invention is a method for detecting a ground fault point in a gas insulated switchgear in which an insulating gas is sealed in a container after a ground fault occurs. , applying a voltage to an area that has been disconnected from the power system and stopped operating due to the presence of a ground fault point, and determining the ground fault point based on information from an insulation abnormality detection sensor provided in the gas-insulated switchgear; It is characterized by this.

(Function) According to the method for detecting a ground fault point in a gas insulated switchgear of the present invention,
Because a ground fault occurred in the GIS, the gas insulated voltage transformer installed in this area was reverse excited and AC voltage was applied to the area that was isolated from the grid and stopped operation, and damage caused by the ground fault arc was applied. By generating a partial discharge in the affected area and detecting this partial discharge with an insulation abnormality detection sensor installed in the gas-insulated switchgear, the operator and maintenance staff at the electrical station can quickly eliminate the need to patrol around the G13 area. Moreover, the ground fault point can be detected accurately.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIG. 1 and FIG. 10.

In this example, as shown in Figures 1 to 4,
In order to locate the ground fault point of GIS, the power transmission line protection area (from the line breaker to the line side), the bus bar protection area, and the transformer protection area (from the transformer breaker to the transformer side) in system protection. ) is provided with a gas insulation voltage transformer (hereinafter referred to as gas PT) as an alternating voltage generation source.

Here, FIGS. 1 to 4 show examples of the arrangement of gas PTs as voltage generation sources, including a single bus bar configuration (Figure 1), which is a typical GIS configuration, and a 2-width 11-wire configuration (Figure 1). Figure 2), 4
The bus tie configuration (No. 121) and the 1 1/2 circuit breaker configuration (Figure 4) are shown. That is, as shown in FIG. 1, in a GIS with a single J line configuration, the line ff1l+ of the line breaker 1 is connected to the transformer 1 from the transformer breaker 2.
A gas PT 25 is connected to the main bus 28 and the main bus 28, respectively.

Similarly, in FIGS. 2 to 4, the power transmission line protection area (line side from the line breaker), the bus bar protection area,
A gas PT 25 is connected to each protection range in the transformer protection area (on the transformer side from the transformer circuit breaker).

Generally, gas PTs are often placed in the power transmission line protection area and the 14-line protection area, and in that case, whether the gas PT can be used as an AC power source, or whether the transformer protection Since no gas PT is placed in the area,
A cass PT or similar voltage source is provided.

Further, a GIS line is generally configured as shown in FIG. That is, the circuit breaker 21, the lJ line breaker 2
2-track ff1ll disconnector 23, earthing switch 24, gas PT 25, cable connection 26, current transformer 27, main bus 2
Each section is separated by an insulating spacer 20. As shown in FIG. 6, this insulating spacer 20 is provided with a buried electrode 201 which is an insulation abnormality detection sensor, and a detection end 1204 is drawn out from this pressed-in electrode 201 to the outside. The built-in electrode 201 is configured so that the electric bed between the conductor 202 and the container 203 can be monitored using capacitance partial pressure.

Next, the basic structure of the gas PT is shown in FIGS. 7 and 8. That is, the primary winding 302 is attached to the iron core 304. Further, the high voltage side of the primary winding 302 is connected to the main circuit via the high voltage terminal 301. Furthermore, 2
The next winding 303 is connected to a protection circuit and an opening circuit through a terminal box 310. 2 of the Kass PT configured in this way
If an AC power source is connected to the secondary winding 303 and the gas PT is reversely excited, a voltage equivalent to the operating voltage can be induced in the primary winding 302.

In the ground fault point detection method of this embodiment having such a configuration, a ground fault point is detected as described below. That is, it is assumed that a ground fault occurs in the section 16 where the first insulating spacer 10 and the second insulating spacer 11 are cut off in the GIS which is operating in the state shown in FIG. The arc generated by such a ground fault inside the GIS is the G
It moves at high speed along the conductor within the IS, stops at the second insulating spacer 11, and remains there until the ground fault current is interrupted. At this time, the second insulating spacer 1
Since the creeping surface of No. 1 is exposed to the arc, it will be damaged.

In such a situation, a command from the protection relay will cause
The line circuit breaker 1, the transformer circuit breaker 2, the busbar connection circuit breaker 3, and the first busbar division circuit breaker 4 are tripped, and the bold line portion in FIG. 10 is disconnected from the system. In this state, connect the AC power supply 17 to the secondary side 8a of the gas PT8 for the upper bus line and
8 is reversely excited, and an alternating voltage is applied to the stop range shown by the thick line in FIG. Then, partial discharge occurs in the second insulating spacer 11, which was damaged by the arc during the ground fault, due to the alternating current voltage generated by reverse excitation of the gas PT3. The high frequency pulse voltage induced by this partial discharge can be detected by the embedded electrode 201 of the insulating spacer shown in FIG. Furthermore, because the insulating spacer is damaged, the voltage ratio between the embedded electrode 201 and the container 203 differs from the normal one, so it is also possible to identify the damaged insulating spacer by detecting this change. Ru. That is, by identifying an insulating spacer that has been damaged by an arc during a ground fault using the method described above, the location where the insulating spacer is located can be determined to be the ground fault point.

In this way, according to this embodiment, the gas PT installed in this area is reverse excited to apply AC voltage to the area that has been separated from the system and stopped operation due to a ground fault occurring in the GIS. By applying an electric current to the insulating spacer that has been damaged by the ground fault arc, and detecting this partial discharge with a push-in electrode installed on the insulating spacer, it is possible to quickly detect the ground fault point. can.

In addition, all the problems with the scales in the conventional detection methods described above can be solved. In other words, there is no need to know the status of ground fault current shunting, and failure current interruption at a circuit breaker, etc. can be mistaken for an accident.1. I + never give up. In addition, since there is no need to provide a through hole for installing a detection sensor in the container, the GI
S gas leakage can also be prevented. Furthermore, if the central processing unit or the like monitors information from the push-in electrodes provided on the insulating spacer, there is no need for operators, maintenance personnel, etc. to patrol around the GIS.

[Effects of valves] As mentioned above, according to this valve, after a ground fault has occurred, an electric bed is placed in an area that has been disconnected from the power system and stopped operating due to the existence of a ground fault point. By applying G15 and determining the ground fault point based on information from the insulation abnormality detection sensor installed in the gas-insulated switchgear B, operators and maintenance personnel can detect the G15 after a ground fault occurs inside the GIS. It is possible to provide a method for detecting a ground fault point in a gas insulated switchgear that can quickly and accurately identify the location of an accident without patrolling the surrounding area.

[Brief explanation of drawings]

Figures 1 to 4 are circuit diagrams showing one embodiment of the ground fault detection method of the present invention, in which Figure 1 shows a single RT line configuration, Figure 2 shows a standard double bus line configuration, and Figure 2 shows a standard double bus line configuration, and a third The figure shows a 4 bus tie configuration, Figure 4 shows a 1 1/2 breaker configuration, Figure 5 is a cross-sectional view showing the configuration of a GIS line with a double busbar configuration, and Figure 6 shows an insulation abnormality detection sensor. A cross-sectional view showing an example of the insulating spacer provided. Fig. 7 is a cross-sectional view showing the configuration of the gas PT. Fig. 8 is a circuit diagram of its main parts. Figs. 9 and 10 are ground faults in a GIS with a 4-bus tie configuration. FIG. 3 is a circuit diagram showing a situation when an accident occurs. 1...Line circuit breaker, 2...Transformer circuit breaker, 3.
...Bus bar communication circuit breaker, 4...11/'] Line division circuit breaker, 5...Bus bar division circuit breaker, 6...Fil
frj line, 7... Otsu bus line, 8... IT1 bus gas PT, 8a... Kano 1 / Secondary side of TJ line gas PT, 9
... Bus line gas PT, 10... First insulating spacer, 11... Second insulating spacer, 12... Transformer,
13... Bushing, 14... "Open" disconnector, 15
... "Closed" disconnector, 16... Ground fault point, 1-7...
AC power supply, 20... Insulating spacer, 21... Circuit breaker, 22... Busbar disconnector, 23... Track side disconnector, 2
4... Earthing switch, 25... Gas PT, 26...
Cable connection part, 27...Current transformer, 28...10R1
Wire, 201... Push-in electrode, 202... Conductor, 20
3... Container, 204... Detection terminal, 301... High voltage terminal, 302... Primary winding, 303... Secondary winding, 304... Iron core, 305... Insulating gas , 306・
...Container, 307... Iron core clamp, 308... High voltage shield, 309... Grounding shield, 310...
・Terminal box, 311...Base, 312...Secondary terminal. Figure 2vA Figure 3 Figure 303 Figure

Claims (1)

[Claims] After a ground fault occurs in a gas-insulated switchgear in which an insulating gas is sealed in a container, a voltage is applied to the area that has been disconnected from the power system and stopped operating due to the presence of a ground fault point, and the gas-insulated switchgear is A method for detecting a ground fault point in a gas insulated switchgear, characterized in that a ground fault point is determined based on information from an insulation abnormality detection sensor provided in the switchgear.