JPH02275372A - Ground fault current sensor and localization of ground fault point - Google Patents

Abstract

PURPOSE:To enable location of a fault point by a method wherein a plurality of terminals are provided in an electromagnetic direction of a ground fault current path and current between terminals is checked to detect a ground fault current easily with handy construction. CONSTITUTION:A transmission wire is arranged near center axes of gas insulated switch (GIS) tanks 11 and 15 made up of a conductor of a low impedance and filled with SF6 gas. Then, terminals 17 are connected to a nut connected to flanges 12 and 16 and ground fault current sensors S11-S15 are provided between the respective terminals 17. In such a condition, when a ground fault occurs at a point P, a ground fault current flows through the tanks 11 and 15 in a direction of earth centered on the point P, thereby enabling detection thereof with the sensors S11-S15. When phases of the sensors S11-S15 are compared, any ground fault point P can be located when existing within a detection section of a ground fault current sensor with normal and opposite phases adjacent to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a ground fault current sensor and a ground fault point locating method for a gas insulated switchgear (GrS) in, for example, a power distribution substation.

(Prior art) Generally, when an accident such as a ground fault occurs in a switchgear, it is necessary to detect the fault point within a narrow range in order to restore the system quickly, so the ground fault point is located.

To detect ground faults and locate the ground fault point in conventional insulated switchgear, in the case of open type insulated switchgear, images are taken every 1,760 seconds, and the imaged screen is visually inspected when a ground fault occurs. Ground faults and ground fault points are located using this method.

However, in the case of a gas-insulated switchgear, which is a closed type, it is difficult to visually locate the ground fault point inside the switchgear because it is sealed. For this reason, a light sensor is installed in the GIS tank to detect the generation of light due to an arc, and an impact pressure relay is used to detect the generation of shocking gas pressure, thereby identifying the occurrence of a ground fault and locating the ground fault point. is being carried out.

(Problem to be solved by the invention) However, optical sensors and impact pressure relays are
It must be installed inside the tank, and if it is already installed, the GI
In the case of major modification or new installation of the S tank, there are problems such as airtightness and complicated maintenance.

Therefore, as shown in FIG. 12, for example, a plurality of transformers CTI, CT2, CT3, C are connected at intervals.
It has been considered that a T4 primary winding is wound around the GIS tank 1 to detect ground fault current.

And load current 1. If a ground fault occurs at two points, the ground fault current ■, will be shunted in the direction of the power supply E and the load, respectively, using the GIS tank 1 as the ground fault path, and the ground fault currents I and l will be shunted to the direction of the power supply E and the load, respectively, using the GIS tank 1 as the ground fault path, and the ground fault currents .

The earth fault current 1.2 passes through the transformer CT3, C
Pass T4.

Furthermore, the current ICT2 flowing through the transformer CT2 is Icy
z=1. I-+ (A) The current I CT3 flowing through the transformer CT3 is Ictv =
1. I, +I, 2(A) where (w = 11+
Since I I 2, Icti=1. 1. +(A).

However, in reality, each transformer CTI, CT2, C
T3.

A load current I is applied to the primary winding of CT4. , it is difficult to reliably detect the ground fault point.

The present invention has been made in view of the above problems, and is a ground fault current sensor and ground fault point locating method that can be easily applied to both existing and newly installed equipment, and that can perform reliable detection at low cost. The purpose is to provide

[Structure of the invention]

(Means for Solving the Problems) A ground fault current sensor according to claim 1 comprises: a conductor forming a ground fault current path; a plurality of terminals of the conductor provided in a direction in which a ground fault current flows; and these terminals. and detection means for detecting an output between the two.

The ground fault point locating method according to claim 2 provides a plurality of ground fault current sensors according to claim 1 on a ground fault current path, compares the phases of the outputs of these ground fault current sensors, and detects a ground fault where the output shows a positive phase. The current sensor and the ground fault current sensor whose outputs are in the opposite phase locate the occurrence of a ground fault accident in any detection section of adjacent ground fault current sensors.

(Function) In the ground fault current sensor according to the first aspect, when a ground fault current flows through a ground fault current path of a conductor, the detection means detects an output between the terminals.

The ground fault point locating method according to claim 2 compares the phases of outputs detected by a plurality of ground fault current sensors, and detects ground fault current sensors whose outputs are in positive phase and ground fault current sensors whose outputs are in reverse phase. The sensor locates the occurrence of a ground fault between any terminals of adjacent ground fault current sensors.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, numeral 11 is a gas insulated switchgear (GIS) tank made of iron or aluminum, which is a low impedance conductor that forms a ground fault current path.This GIS tank 11 has a T-shaped cylinder. In combination, the three ends are each formed with a flange 12.12.degree. 13.

In addition, 15 is a straight cylindrical GIS tank, and this GI
Similarly, flanges 16 are formed at both ends of the S tank 15. Then, the flange 12 of the GIS tank 11 and the G
The flange 16 of the IS tank 15 is fastened with bolts and nuts.

Further, a power transmission line connected to the power source E is arranged along the axial direction near the center axis of each of the GIS tank 11 and the GIS tank 15, and inside the GIS tank 11 and the GIS tank 15, , filled with sulfur hexafluoride gas (SF6).

Then, connect the terminal 17 to a nut (not shown) that connects the connected flanges 12.16, and
In between, each ground fault current sensor 311. SI2゜S
13. 314. 815 is optionally provided as necessary.

Note that when the distance between the terminals 17 and 17 is wide, the GIS tank 11. A terminal 17 is provided on the outer peripheral surface of the terminal 15.
If the distance between terminals 17 and 17 is shortened, or conversely, the distance between terminals 17 and 17 is short, connect the ground fault current sensor S between terminals 17 and 17 of every two or more GIS tanks 12.
The distance between the terminals 17 and 17 may be increased.

As the ground fault current sensor S, for example, a transformer 18 is used as shown in FIG. In this case, terminal 17.1
Both ends of a primary winding 19 of a transformer 18 are connected between 7 and 7, and ground fault current is detected from the output of a secondary winding 20. In this way, when the insulated transformer 18 is used, the secondary winding 2θ side can be made common to one line, for example, as shown in FIG. 3, so the circuit configuration on the secondary side is simplified and the processing Can be easily processed as output.

Further, as shown in FIG. 4, a transformer 21 may be used for the ground fault current sensor S. In this case, the terminals 17, 17 are short-circuited, and the primary winding of the transformer 21 is passed through this short-circuited portion.

Next, a case where a ground fault occurs at point P in the structure shown in FIG. 1 will be described.

Normally, a load current flows through a power transmission line (not shown) in the GIS tank If, 15 from the left to the right in the drawing.

If a ground fault occurs at point P in this state, the GIS tank 11
．． 15, a ground fault current flows in the direction of the ground around point P (that is, in the direction of the dashed arrow). At this time, the phases of the ground fault current sensor Sll and the ground fault current sensor 812 are reversed,
The phases indicated by the ground fault current sensor S13, ground fault current sensor S14, and ground fault current sensor S15 are reversed. Then, the phases of these ground fault current sensors 311 to S15 are compared, and the positive phase and reverse phase are determined. Adjacent ground fault current sensor S12
Alternatively, it is possible to locate the ground fault point P within any detection section of the ground fault current sensor S13.

Next, the experimental results when a simulated ground fault current was applied to the example will be explained with reference to FIG.

The GIS device shown in FIG. 5 has eight GIS tanks 21 to
28, each GIs tank 2
1 to 28 are respectively provided with ground fault current sensors S1 to S8 as shown in FIG.
1 to S8 perform analog processing on the voltage waveform to represent the phase.

Then, ground fault points PI and GI are placed at the ends of the GIS tank 21.
Ground fault points P2 and G on the GIS tank 22 side of the S tank 23
Ground point P3 in the center of IS tank 23, GIS tank 2
3, ground fault point P4 on the GIS tank 24 side, ground fault point P5 on the GIS tank 25, and ground fault point P6 on the GIS tank 27 side.
When a ground fault point P7 is set at the end of the GIS tank 28 and a simulated ground fault current is passed from inside the GIS tank, the voltage phases shown in Table 1 appear in each sensor.

(See next page) As shown in Table 1, according to experiments, the phase (underlined part) that appears in a GIS tank through which a simulated earth-rated current flows is
Since this phase is substantially opposite to the phase appearing in the IS tank and is significantly different, the ground fault point can be easily located.

Next, in order to investigate the effect of the load current flowing inside the GIS tank on the sensor, a ground fault current was applied from outside the GIS tank. Table 2 shows the experimental results comparing the case where the ground fault current was caused to flow from inside the GIs tank shown in Table 1. In this case, the ground fault point pH,
Ground fault point P12 on the flange of GIS tank 22 and GIS tank 23, ground fault point P14 on the flange of GIS tank 23 and GIS tank 24, ground fault point P15 on the flange of GIS tank 24 and GIS tank 25, G
A ground fault point P16 is set at the flange of the IS tank 27 and the GIS tank 28, and a ground fault point P17 is set at the end of the GIS tank 28, respectively, and a comparison is made in Table 2 with a case where a ground fault is caused inside the GIS tank. explain.

As shown in Table 2, even when a ground fault current is passed inside the GIS tank, the influence of the load current flowing inside the GIS tank can be ignored. It can be seen that the load current flowing inside the GIS tank does not affect the sensor because the phases appearing in the GIS tank are similar.

Next, referring to FIG. 6 and FIG. 7, a device for locating a ground fault point by comparing the phase of the ground fault current of the grounding wire and the phase of each fault current sensor will be explained. The device transmits to each fault current sensor 5l-88 of the device shown in FIG. 5 the phase detected by the clamp transformer C connected to the ground fault line and the phase detected by the ground fault current sensors S1 to S8. The phase comparison devices F1 to F8 that compare the ground fault current sensor S1
~S8 is connected.

These phase comparison devices F1 to F8 are, as shown in FIG.
1 to F7 are connected to each other.

These phase comparators F1 to F7 are connected to adjacent ground fault current sensors S, as shown in FIG.

S is connected to a waveform shaper 32 via an amplifier 31. Furthermore, in this waveform shaper 32, each fault current sensor S, S, and transformer C are connected to an amplifier 31 for amplification, and this amplifier 31 is connected to a waveform shaper 32 for waveform shaping. The waveform shaper 32 also includes a phase meter 33 that measures the phase of the ground fault current sensor S, and a phase meter 33 that measures the phase of the ground fault current sensor S.
and the clamp transformer C.
is connected. Furthermore, this phase comparator 34 has
A display 35 that displays the location of the opposite phase using, for example, a light emitting diode, and a digital indicator 36 that digitally displays the phase difference between the ground fault current sensor S and the clamp transformer C are connected. Further, the display 35 and the digital indicator 36 are provided, for example, on a panel of an operation panel.

Then, in normal times, everything is in normal phase, so
The display 35 does not display, and the digital indicators 36 each display the phase difference with the clamp transformer C. When a ground fault occurs, the ground fault current sensor S indicating the reverse phase appears due to the ground fault, and the phase comparator 34 lights up the light emitting diode corresponding to the ground fault current sensor that is determined to have the reverse phase. , indicates that the phase is reversed.

Then, in one of the detection sections where the ground fault current sensor indicating the positive phase and the ground fault current sensor indicating the negative phase are adjacent,
It is possible to locate that a ground fault has occurred.

Note that the phase to be compared is not limited to the ground fault current flowing through the ground wire, but may also be the load current in the GIS tank.

Further, with reference to FIGS. 8 and 9, a device for locating a ground fault point by comparing the phases of adjacent ground fault current sensors will be described.

The device shown in FIG. 8 includes a phase meter 33 for measuring the phase of each adjacent ground fault current sensor S, and a phase meter 33 between each adjacent ground fault current sensor S, S of the device shown in FIG. A phase comparator 34 is connected to compare the phases, and this phase comparator 3
4 includes an adjacent ground fault current sensor S, an indicator 35 for detecting a location where the phase of S is reversed, and an adjacent ground fault current sensor S,
Digital indicator 36 that digitally displays the phase difference with S
is connected.

Then, in normal times, everything is in normal phase, so
The display 35 does not display any information, and the digital indicators 36 are connected to adjacent ground fault current sensors S, respectively.

Displays the phase difference between 8. When a ground fault occurs, some of the ground fault current sensors S exhibit reverse phase.

When it is determined that the phase is reversed between the adjacent ground fault current sensors S, the light emitting diode corresponding to the adjacent ground fault current sensor S that displays the reverse phase is turned on, and the adjacent ground fault current sensor Displays that S is in reverse phase.

Then, it is possible to locate that a ground fault has occurred in the detection section of either one of the ground fault current sensors S, S which show the positive phase and negative phase adjacent to each other.

Furthermore, with reference to FIGS. 10 and 11, a device for detecting the peak value of a ground fault current sensor and locating a ground fault point will be described.

In the device shown in FIG. 10, all the ground fault current sensors S of the device shown in FIG. 5 are connected to a level determination device that determines the ground fault current sensor S with the highest voltage output value. . Note that the specific impedance of each GIS tank 21 to 28 is not the same, and each GIS tank 21 to
The 28 characteristic impedances are different. In addition, each fault current sensor S is connected to the amplifier 31, and connected to a peak value detector 37 that detects the peak value of the voltage via the waveform shaper 32, and the level determination bag ff1i [L is connected to the peak value detector 37 that detects the peak value of the voltage. A display device 35 is connected to the device 37 .

Then, when a ground fault occurs, the voltage of the ground fault current sensor S whose detection section includes the part where the ground fault occurred rises the most, and the peak value detector 37 detects the highest voltage. The light emitting diode corresponding to the section where the ground fault occurred on the display 35 lights up, and the point of the ground fault can be located.

Note that current may flow through the GIS tank due to the load current within the GIS tank and other causes. In this case, when a ground fault occurs, a current in which a normal current is superimposed on the ground fault current flows, making it impossible to detect only the true ground fault current. Therefore, in the case of superimposed currents like this, the output of each sensor is constantly monitored and recorded, rewritten at regular intervals, and when a ground fault occurs, the current immediately before the fault occurs, that is, during normal times, is subtracted. You can know the phase of the true ground fault current.

Further, the ground fault current sensor can be used as a sensor for detecting short circuit current if it is installed on a leg of a tower of a high-voltage power transmission line.

〔Effect of the invention〕

According to the ground fault current sensor of the first aspect, since the terminals are provided in the current direction of the ground fault current path and the output between the terminals is detected, the ground fault current can be easily detected with a simple configuration.

According to the ground fault point locating method of claim 2, by detecting the phase of the output between the terminals of the ground fault current sensor of claim 1,
Since the point of the ground fault is located, the point of the ground fault can be easily located.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a block diagram showing the ground fault current sensor of the above, Fig. 3 is a connection diagram of the ground fault current sensor of the above, and Fig. 4 is a diagram of the ground fault current sensor of the above. A block diagram showing the fault current sensor, Fig. 5 is an explanatory diagram showing the ground fault test device as above, Fig. 6 is an explanatory diagram showing the ground fault point locating device, Fig. 7 is a block diagram showing the locating device as above, Fig. 8 The figure is an explanatory diagram showing another ground fault point locating device, FIG. 9 is a block diagram showing the same locating device, FIG. 10 is an explanatory diagram showing another ground fault point locating device, and FIG. 11 is an explanatory diagram showing the same locating device. Explanatory diagram showing 12th
The figure is a theoretical diagram showing a conventional example. Il, 15... GI of the conductor forming the ground fault current path
S tank, 17...terminal, S...sensor as a detection means.

Claims (2)

[Claims] (1) A conductor that forms a ground fault current path, a plurality of terminals provided in the direction in which the ground fault current flows in this conductor, and a detection means that detects the output between these terminals. Ground fault current sensor. (2) A plurality of ground fault current sensors according to claim 1 are provided in the ground fault current path, and the phases of the outputs of these ground fault current sensors are compared,
A ground fault current sensor whose output shows a positive phase and a ground fault current sensor whose output shows a negative phase locate the occurrence of a ground fault accident in any detection section of adjacent ground fault current sensors. Ground fault point location method.