JPH0526946A - Ground fault accident detection device for distribution system - Google Patents

Abstract

(57) [Abstract] [Purpose] The current flowing between the support that supports the distribution line and the ground is detected, and both the current flowing through the support and the current flowing through the ground line are detected, and the detection signals are compared. The ground fault detection performance is improved by calculation. A first current detector that detects a current flowing between a support body that supports a distribution line and an overhead ground wire; a current that flows between the support body and the overhead ground wire, and the support body and an electric conductor wire; A second current detector for detecting a current flowing in an electric conductor grounded to the ground is provided, and these detection signals are compared and calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground fault detecting device,
In particular, it relates to a ground fault accident detection device for a distribution system.

[0002]

2. Description of the Related Art FIG. 4 shows a support structure for distribution lines.
Numeral 1 is a utility pole, which is made of wood, but recently it is mostly made of concrete. 2 is a arm (arm), 3 is an arm tie, 4,
Reference numerals 5 and 6 are insulators, and 7 is a metal band. Reference numeral 8 denotes a metal conductor, of which there are various types, but here, it is shown as a cap-type metal cap. 9 is an overhead ground line, 10 and 1
Reference numerals 1 and 12 are three-phase high-voltage distribution lines, and insulators 4,5 and 5, respectively.
It is supported by the arm 2 through 6. Reference numerals 13, 14, and 15 are insulators, and reference numerals 16, 17, and 18 are low-voltage light wires of a single-phase, three-wire type, of which 16 are grounded to form a common ground wire. Reference numeral 19 is a transformer arm, 20 is an insulator, 21 is a single-phase transformer, and the primary winding 22 is a high voltage electric wire 10 to 1.
The center tap of the secondary winding 23 is connected to the low-voltage light wire 16, and the other windings are connected to the low-voltage light wire 17,
It is connected to 18. Reference numeral 24 is a case of the single-phase transformer 21. 25a to 25e are ground lines 25. Earth 2
The ground impedance of 6 is typically on the order of tens of ohms.

One of the improvements in the reliability of power supply is to shorten the power outage time. To that end, it is important to find the location of the accident and the equipment early. Therefore, a current transformer (CT) is installed in each device for the purpose of detecting a ground fault that requires a long time to find the fault because it is difficult to find the fault, and the ground fault is centrally monitored. A system that does is possible. However, when a current transformer for detection is installed on these monitored equipment, the transformer, switch, arrester, underground cable, etc. can be easily installed structurally, but the insulator is structurally and the number of members is small. It is necessary to take measures such as minimizing the number of current transformers in consideration of economic efficiency due to the large number of current transformers.

[0004]

Since the insulator is directly attached to the arm and the insulator is more reliable than other devices, it is not necessary to detect the ground fault for each phase, and it is possible to use the three phases collectively. Is enough. However, even if a current transformer is attached to the arm or arm tie, the ground fault current of an accident that occurred in another pillar flows through the overhead ground wire (GW) and flows into the arm from the cap, and thus malfunction easily occurs.

In order to prevent this, means shown in FIGS. 4 to 7 can be considered. That is, as shown in FIG. 5, a current transformer 28, which is a current detector, is installed in the cap 8,
The ground wire 25, which extends from the insulators 4, 5, 6 through the arm 2 and the arm tie 3 to the ground 26, is passed through the current transformer 28. 27 is a grounding resistance of the grounding wire 25.

6 to 7 are equivalent circuits of FIG.
When the ground fault current I ₁ flows from the other pillar, it is canceled on the primary side of the current transformer 28, as shown in FIG. Further, in the case of a ground fault of the insulator of its own pillar, the ground fault current I _L of the insulator can be detected as shown in FIG. However, as shown in FIG. 8, when the value R _P of the leak resistance 29 of the telephone pole 1 is small and the leak current I ₃ thereof is large, (I ₁ −I ₂ ) = I ₃ , and this I ₃ is greater than the threshold value. Also becomes large and malfunctions.
The reason is that the decrease in impedance of concrete columns (con pillars) is presumed to be because the through bolts that fix the arms and arm ties to the con pillars are in contact with the reinforcing bars in the con pillars, but several tens of Ω or less (regular As a result of actual measurement, it was found that there are 20 to 30% or more of the pillars (which are almost equivalent to the ground resistance of the ground wire).

A method shown in FIGS. 9 and 10 can be considered as a means for canceling the leakage of the concrete column. FIG. 10 is an equivalent circuit of FIG. That is, the current transformer 28b is installed in the cap 8 and the current transformer 28c is installed in the con pillar 1, and the secondary sides of these two current transformers are differentially connected. Therefore, this method can cancel the leakage current of the column 1. However, the current transformer 28c provided on the lower side of the con pole 1 needs to have a through diameter equal to or larger than the diameter of the con column (400 mm), and in consideration of mounting, the current transformer core must have a structure that can be divided. Therefore, considering cost and reliability, it is not practical.

The present invention has been made in view of the above-mentioned problems, and an object thereof is a high-voltage circuit ground fault caused by insulation deterioration of an insulator which is an insulating support of a distribution line and a high-voltage device attached to a metal arm. An object of the present invention is to provide a ground fault detection device capable of identifying a ground fault with high performance without depending on the load current of the low voltage circuit or the ground fault current of another pillar at the fault point.

[0009]

In the ground fault accident detecting apparatus of the present invention, a first current detector for detecting a current flowing between a support body supporting a distribution line and an overhead ground wire, and the support body and the aerial body A second current detector for detecting a current flowing between ground lines and a current flowing in an electric conductor grounded to the ground via the support and an electric conductor is provided, and electric signals of the first and second current detectors are provided. And a ground fault of the distribution line is detected.

The present invention also provides a first current detector for detecting a current flowing between a support and an overhead ground wire, and a first current detector for detecting a current flowing through an electric conductor grounded to the ground via the support and an electric conductor. The second current detector is provided, and the ground signal of the distribution line is detected by comparing the electric signals of the first and second current detectors.

Furthermore, in each item, a ground fault of a distribution line is detected by comparing changes in electric signals of the first and second current detectors, and a ground fault of a distribution system is detected. Is.

[0012]

The detection signal S4 of the first current detector that detects only the current flowing between the support and the overhead ground wire, the current flowing between the support and the overhead ground wire, and the ground side from the support through the electrical conductor. Is compared with the detection signal S5 of the second current detector that detects both of the currents flowing in the column, and if S5 <S4, it is determined that the ground fault has occurred in another pillar.

The detection signal S5 exceeds the threshold value and S5 <
When it is S4, it is judged that there is no accident in its own pillar, and it is judged as an accident in another pillar, and when the signal S5 exceeds the threshold value and S5 ≧ S4, it is judged that it is an accident in the insulator of its own pillar, and the signal S5 judges the threshold value. If it does not exceed the threshold, it is judged that there is no accident in the pillar.

Further, the detection signals S4 and S5 are calculated by the equation (1), and S5 / S4 ≧ K (1) As a result, when the calculation result S5 / S4 is equal to or higher than the detection sensitivity constant K, it is determined that the insulator of the pillar is the accident. .

The detection signal S4 of the current flowing between the support and the overhead ground wire and the detection signal S5 of the current flowing from the support to the ground side via the electric conductor are compared and calculated (S4−S5) <S4. Judged as a pillar accident. When (S4-S5) exceeds the threshold value and (S4-S5) <S4, it is determined that there is no own pillar accident and another pillar accident, and (S4-S5) exceeds the threshold value and (S4-S5). When ≧ S4, it is determined that there is an accident in the insulator of the own pillar, and when the signal (S4-S5) does not exceed the threshold value, it is determined that there is no accident in the own pillar. Further, the variation of the detection signal S4 is ΔS4, and the variation of the detection signal S5 is ΔS5.
Then, the values are calculated and compared, and when ΔS4> ΔS5, it is determined that the ground fault has occurred in another pillar.

[0016]

Embodiments of the present invention will be described below with reference to FIGS.

1 and 2 show a ground fault detector for a power distribution system according to an embodiment of the present invention, in which a metal cap 8 has a current transformer 28a as a first current detector and a second current detector. The current transformer 28b, which is a vessel, is installed, and the outputs of these are compared by the arithmetic processing unit 30 to determine whether it is a sneak from another pole or an accident of the own pole.

As shown in FIG. 2, the sneak current I ₁ due to the ground fault of another pillar flows into the cap 8 through the overhead ground wire 9. The current I ₁ shunting the sneak that has flowed into the cap 8 is divided into the con pillar 1 and the ground wire 25 as I ₂ and I ₃ , respectively,
It flows into the ground 26 through the resistors 27 and 29.

The current transformer 28a detects the sneak current I ₁ and inputs the detection output signal S1 to the arithmetic processing unit 30. Further, the current transformer 28b is connected to the sneak current I ₁ and the ground wire 2
The current I ₃ = I ₁ −I ₂ flowing in 5 is differentially detected and the detection output signal S 2 is input to the arithmetic processing unit 30. As described above, there is no possibility of R _E >> R _P between the regular ground resistance R _E of the ground line 25 and the leak equivalent resistance R _{P of the} concrete column 1, so S2 <S1 and the arithmetic processing unit 30 Judging S2 <S1, the ground fault signal S3 at the ground pillar is output.

In the case of the ground fault of the insulator in the self-pillar, as shown in FIG. 1, the ground fault current I _L from the insulator 4 (5, 6)
Is a current I ₅ flowing into the overhead ground wire 9 through the cap 8,
It is shunted into a current I ₆ flowing into the earth 26 through the connecting pole 1 and a current I ₇ flowing into the earth 26 through the ground wire 25. Therefore, the current transformer 28a detects the current I ₅ and inputs the detection output signal S4 to the arithmetic processing unit 30.
Current transformer 28b current I ₅ and the current _{I 7 = I L - (I} 5 + I 6)
And are detected dynamically and the detection output signal S5 is input to the arithmetic processing unit 30.

However, normally S5 ≧ S4,
When R _E and R _P are large and the sneak current I ₅ to the other column is large, S5≈S4. Therefore, when the signal S5 exceeds the absolute value level and S5 <S4, the arithmetic processing unit 30
Judges that there is no accident in its own pillar, and it is an accident in another pillar. Also,
When the signal S5 exceeds the absolute value level and S5 ≧ S4, the arithmetic processing unit 30 determines that it is an insulator accident of its own pillar. Further, when the signal S5 does not exceed the absolute value level, the arithmetic processing unit 30 determines that there is no accident in its own pillar.

The arithmetic processing section 30 sends the arithmetic processing signal S3 or S6 as a signal of the slave station. When the ground fault current detected by the current transformer installed in each device of the power distribution system exceeds the threshold value, it is held in the storage device of the slave station. The master station calls each slave station, and when it detects the accident information, it transmits the accident information to the branch office and sales office via the power distribution teleconverter.

According to the above-described embodiment, the detection signal of the first current detector for detecting the current flowing through the metal cap and the second current detection for detecting both the current flowing through both the metal cap and the ground line. By detecting the ground fault by comparing and calculating with the detection signal of the transformer, it is possible to prevent the detection malfunction due to the leak of the concrete column, and the two current transformers to be used have a penetration diameter to pass through the cap part. Is relatively small, and when installing it, the overhead ground wire can be removed from the top of the cap and staggered horizontally so that it can be inserted from above the cap. A highly reliable detection device can be obtained.

FIG. 3 shows a ground fault accident detecting apparatus according to another embodiment of the present invention. In the ground fault accident detecting apparatus of this embodiment, a current I ₁ flowing through a ground wire 25a connected to an overhead ground wire 9 is shown.
Is detected by the first current detector 28a, and the insulator 4
Ground wire 25 connecting (5, 6) and low voltage common ground wire 16
The current flowing in b is detected by the second current detector 28b.

According to the ground fault accident detection apparatus of FIG. 3, the insulator 4 supporting the overhead ground wire 9 and the high voltage distribution line 10 (11, 12).
The current I ₁ flowing through the ground line 25a between (5, 6) is detected by the first current detector 28a, and the detection signal S ₁ is input to the arithmetic processing unit 30. Further, the current I ₃ flowing in the ground wire 25b between the insulator 4 (5, 6) and the common ground wire 16 is detected by the second current detector 28b, and its detection signal S _{2 is} detected.
Is input to the arithmetic processing unit 30. Here, the current I ₃ is the difference I ₃ = (I ₁ −I ₂ ) between the currents I ₁ and I ₂ , and the arithmetic processing unit 30 detects the ground fault accident based on these current relationships.

[0026]

As described above, according to the present invention, the first current detector for detecting the current flowing between the support supporting the distribution line and the overhead ground wire, and the current flowing between the support and the ground. A second current detector for detecting a ground fault, and the detection signals of the first and second current detectors are effectively compared and calculated to detect a ground fault. The high-voltage circuit ground fault accident point that occurs due to insulation deterioration of the insulators and high-voltage equipment attached to the metal arm does not depend on the load current of the low-voltage circuit or the ground fault current of other pillars, and the ground fault accident can be performed with high performance. It is possible to obtain a ground fault accident detection device that can be specified.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a ground fault accident detection device for a power distribution system according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a ground fault accident detection device of a power distribution system according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a ground fault accident detection device of a power distribution system according to another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a connection example of telephone poles that are supports.

FIG. 5 is an explanatory diagram showing a conventional ground fault accident detection device for a power distribution system.

6 is an equivalent circuit diagram of the ground fault accident detection device of FIG.

FIG. 7 is an equivalent circuit diagram of the ground fault accident detection device of FIG.

8 is an equivalent circuit diagram of the ground fault accident detection device of FIG.

FIG. 9 is a configuration diagram of a conventional ground fault detection device for a distribution system.

10 is an equivalent circuit diagram of the ground fault accident detection apparatus for the power distribution system of FIG.

[Explanation of symbols]

1 ... Concrete pillar 4, 5, 6 ... Insulator 8 ... Metal cap 9 ... Overhead ground wire 16 ... Low-voltage common ground line 25, 25a, 25b, 25e ... Ground wire 26 ... Earth 27 ... Ground resistance 28a ... Current transformer which is the first current detector 28b ... Current transformer which is a second current detector 29 ... Earth resistance of concrete columns 30 ... Arithmetic processing unit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Haga             1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture             Hitachi Kokubu Factory (72) Inventor Yasuo Kataoka             2-17 Osaki, Shinagawa-ku, Tokyo Stock market             Shameidensha (72) Inventor Tadashi Miyano             2-17 Osaki, Shinagawa-ku, Tokyo Stock market             Shameidensha (72) Inventor Yasuyuki Mikami             2-17 Osaki, Shinagawa-ku, Tokyo Stock market             Shameidensha

Claims (3)

[Claims] 1. A distribution line is insulated and supported by a support on a concrete column, an overhead ground wire is supported on the concrete column, and the support and the overhead ground wire are connected by an electric conductor, and the support is electrically connected. In a distribution system grounded to the ground via a conductor, a first current detector for detecting a current flowing between the support and an overhead ground wire, a current flowing between the support and the overhead ground wire, and the support A second current detector for detecting a current flowing in an electric conductor grounded to the ground through the body and the electric conductor is provided, and the detection signals of the first and second current detectors are compared to each other to detect the ground of the distribution line. A ground fault accident detection device for a distribution system, which is characterized by detecting a fault. 2. A distribution line is insulated and supported by a concrete pillar by a support, an overhead ground wire is supported by the concrete pillar, and the support and the overhead ground wire are connected by an electric conductor, and the support is In a distribution system grounded to the ground via an electric conductor, a first current detector for detecting a current flowing between the support and an overhead ground wire, and an electric conductor grounded to the ground via the support and the electric conductor. A second current detector for detecting a current flowing through the ground, and detecting a ground fault of the distribution line by comparing electric signals of the first and second current detectors. Detection device. 3. The method according to claim 1 or 2, wherein:
And a ground fault of a power distribution system, which detects a ground fault of a distribution line by comparing a change amount of an electric signal of the second current detector.