JPH10239366A - Zero phase voltage detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect zero phase voltage without being affected by the other phase electric field by providing electrostatic capacity potential dividers respectively in three phase high tension distribution line paths such that distances between the centers of three electrostatic potential dividers are equalized. SOLUTION: An electrostatic capacity potential divider consists of a high tension conductor part 1, an inside electrode 2 formed inside a porcelain insulator, an induction body 3 and an outside electrode 4 formed outside the porcelain insulator. The high tension conductor part 1 is connected electrically to the inside electrode 2. An electrostatic capacity is formed between the inside electrode 2 and the outside electrode 4. An electrostatic capacity formed between the outside electrode 4 and other phase outside electrode depends on distances between the centers of three electrostatic capacity potential dividers, i.e., the outside electrodes 4 provided in respective three-shape high tension distribution line paths. Thus, when the distances between these centers are equalized, other phase electric fields received by the respective outside electrodes 4 are equalized and subjected to vector addition to be utterly cancelled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero-phase voltage detecting device used for detecting an accident such as a ground fault in a high-voltage distribution line.

[0002]

2. Description of the Related Art Conventionally, this kind of zero-sequence voltage detecting device has a configuration as shown in FIG.

In FIG. 4, 1 is a high-voltage conductor, 2 is an inner electrode, 3 is a dielectric forming an insulator, 4 is an outer electrode, 5 is an optical voltage sensor, and 6 is a high-pressure air switch filled in a switch. Is a filler. A capacitance C ₂ is formed between the high-voltage conductor 1 and the inner electrode 2. Further, a capacitance C ₁ is formed between the inner electrode 2 and the outer electrode 4. FIG. 5 shows this in an equivalent circuit. When the capacitance of the optical voltage sensor 5 is sufficiently smaller than the capacitances C ₁ and C ₂ , the voltage between the voltage application terminals 7 and 8 of the optical voltage sensor 5 and the one-phase ground The voltage division ratio R, which is a ratio with respect to the voltage, is represented by (Equation 1).

[0004]

(Equation 1)

At this time, considering the phase of each phase voltage,
The voltage V _S applied to the optical voltage sensor 5 is as follows: V _ZX = V _A * R + V _B * R * COS (120 °) + V _C *
R * COS (240 °) V _ZY = V _B * R * SIN (120 °) + V _C * R * SIN
(240 °) V _S = (V _ZX ² + V _ZY ² ) ^1/2 where _VA : A-phase ground voltage V _B : B-phase ground voltage V _C : C-phase ground voltage . Normally, the absolute values of V _A , V _B , and V _C are equal, and the voltage applied to the photovoltage sensor 5 is almost zero. Can be detected.

[0006]

As described above, in the conventional configuration, when considering the center-to-center distances of the capacitive voltage dividers of the respective phases as shown in FIG. The distances between the C phases are equal, but the distances between the A phase and the C phase are different. A capacitance is formed between the outer electrode 4 and the outer electrode 4 of the other phase, and is spatially affected by the other-phase electric field. The effect of this component on the A phase and the C phase is the same, but the effect on the B phase is different.
There is a problem that the zero-phase voltage value is detected even though there is no abnormality in the high-voltage distribution line.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a three-phase high-voltage distribution line with a capacitive voltage divider provided at each of the three phases. They are arranged so that the distances are equal.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first aspect of the present invention is to convert a zero-phase voltage generated by dividing a ground-to-ground voltage of a three-phase high-voltage distribution line by a capacitive voltage divider and adding the resultant to a vector. It is applied to a voltage sensor to detect an accident in a high-voltage distribution line.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a high-voltage conductor, 2 is an inner electrode formed inside the insulator, 3 is a dielectric constituting the insulator, 4 is an outer electrode formed outside the insulator, and 9 is an outer electrode of each phase. Connected lead wires. 10
Is a dielectric capacitor for voltage division, 5 is an optical voltage sensor, 11
Is an optical fiber for transmitting and receiving light to and from the optical voltage sensor 5,
Reference numeral 12 denotes a packing for fixing the optical fiber 11 and keeping the inside and outside of the switch airtight. Reference numeral 13 denotes a high-pressure air switch. The high-voltage conductor 1 and the inner electrode 2 are electrically connected. The capacitance C ₁ is formed between the inner electrode 2 and the outer electrode 4. FIG. 2 shows an equivalent circuit of this voltage divider. Assuming that the capacitance of the dielectric capacitor 10 is C ₃ and the capacitance of the optical voltage sensor 5 is C ₄ , a voltage division ratio R, which is a ratio of the voltage between the ground and the voltage applied to the optical voltage sensor, Becomes (Equation 2).

[0010]

(Equation 2)

On the other hand, the zero-phase voltage value applied to the optical voltage sensor 5 can be expressed by the following equation. V _ZX = V _A * R + V _B * R * COS (120 °) + V _C *
R * COS (240 °) V _ZY = V _B * R * SIN (120 °) + V _C * R * SIN
(240 °) V _S = (V _ZX ² + V _ZY ² ) ^1/2 where V _A : A-phase ground voltage V _B : B-phase ground voltage V _C : C-phase ground voltage The capacitance C _T formed between the outer electrode 4 and the outer electrode of the other phase is given by (Equation 3), which indicates that it depends on the center distance a.

[0012]

(Equation 3)

However, as in the present invention, if the distances between the centers of the capacitive voltage dividers are equal, the other-phase electric fields received by the outer electrodes 4 of each phase are equal, and the vectors are added on the voltage divider. In the case of the voltage divider configuration described above, all are canceled out.

FIG. 3 shows an example in which a capacitance voltage divider is provided on a down line to a control transformer. 14 is the downline, 1
Reference numeral 5 denotes a circuit for transmitting and receiving an optical signal to and from the optical voltage sensor 5.

In the embodiment shown in FIG. 1, the three-phase divided voltages are vector-added on the capacitive voltage divider, and the zero-phase voltage is detected by one optical voltage sensor 5. As described above, a voltage sensor may be attached to each phase, and arithmetic processing may be performed on the circuit 15.

[0016]

As described above, according to the present invention, by disposing the capacitive voltage dividers on the three-phase high-voltage distribution line such that the center distances of the three capacitive voltage dividers are equal to each other, There is an effect that a zero-sequence voltage can be detected without being affected by the phase electric field.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a zero-phase voltage detection device according to an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram showing a voltage divider circuit of the zero-phase voltage detection device.

FIG. 3 is a perspective view showing a zero-phase voltage detecting device according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional zero-sequence voltage detecting device.

FIG. 5 is an equivalent circuit diagram showing a voltage divider circuit of the zero-phase voltage detection device.

FIG. 6 is a sectional view of the apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High voltage conductor part 2 Inner electrode 3 Dielectric 4 Outer electrode 5 Optical voltage sensor

Claims (1)

[Claims] 1. A three-phase high-voltage power distribution line, wherein a capacitance divider is provided in each of the three-phase high-voltage distribution lines, and the three-phase three capacitance dividers are arranged so that their center distances are equal to each other. Phase voltage detector.