JPH0668509B2 - Zero-phase voltage detector for three-phase power line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used for a three-phase electric line of a transmission / distribution line, and detects and measures a zero-phase current and a zero-phase voltage of the electric line to find a line fault. The present invention relates to a zero-phase voltage detector for a three-phase power line.

(Prior Art) With the diversification of power demand in recent years, it is necessary to accurately and promptly respond to power supply. For this reason, the supply and management facilities of the electric power system will be complicated and diversified, and
Automation system development and commercialization are being promoted. Therefore, it is necessary to collect the information related to the power supply, for example, to detect and measure the line voltage and current, accurately and quickly, and in a wide range at a large number of places.

By the way, conventionally, as an apparatus for detecting and measuring a zero-phase current and a zero-phase voltage in a three-phase electric line, for example, there is an apparatus as shown in FIGS. 3 and 4.

As shown in FIG. 3, the device for detecting and measuring the zero-phase current is such that the lead wire 43 of the secondary output terminal of the current transformer 42 attached to the electric wire 41 is connected in series and is connected to the lead wire 43. The resistor 44 was connected to both ends of the wire 43. The output terminals 45, 45 are adapted to output a voltage change corresponding to a change in the zero-phase current of each electric wire 41.

In the device configured as described above, the electrical signal output from the output terminals 45, 45 in a normal state is a zero-phase current in which the phase sum of the phase currents shows a zero value. However, when a line fault occurs, the electrical signals output from the output terminals 45, 45 do not show a zero value, and a change in the electrical signal according to the scale of the line fault is output.

On the other hand, the device for detecting and measuring the zero-phase voltage is a three-phase transformer in which the primary terminal Y is connected to the electric wire 41, as shown in FIG.
Alternatively, the resistor 44 is connected to both ends of the lead wire 43 that is connected by opening the secondary side terminals of the three single-phase transformers 46, and the zero-phase voltage of each electric wire 41 is output from the output terminals 45 and 45. The voltage change was output according to the change of.

(Problems to be Solved by the Invention) However, the above-described conventional device has a drawback that the lead wire 43 led out from the current transformer 42 or the transformer 46 is easily affected by electromagnetic induction from the outside. . In particular, in recent years, the reliability of power transmission and distribution lines has been further improved, and accidents that were previously difficult to detect (instantaneous ground faults, intermittent ground faults, etc.)
It is becoming necessary to detect the stable line voltage
Current signal detection is desired.

Also, due to the deterioration of the lead wire 43, there is a possibility of a short circuit accident, and the current transformer 4
2 or the insulation of the transformer 46 deteriorated, which could lead to a ground fault.

In order to prevent inductive damage or insulation aging at the detection point as described above, for example, an optical sensor having a Pockels effect is provided in each phase of the electric line to detect the voltage, and the optical sensor is biased at a constant value. It is known that the zero-phase voltage is measured by connecting in series via a wave optical fiber and obtaining the vector sum of each phase signal. However, there has been a demand for the development of a power detection device capable of detecting a zero-phase current necessary for system monitoring of an electric line and having a small installation space for installation on the electric line.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a facility for an electric line and a zero-phase detection device for a three-phase electric wire suitable for practical use.

Structure of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention is an optical transmission system in which a light emitting portion is connected to one end and a light receiving portion is connected to the other end. In the zero-phase power detection device of the three-phase power line, which is provided with an individual power detection unit connected to each other in series in the middle portion of the path and attached to each phase electric wire, the power detection unit is a plurality of An electric current side metal fitting having a hollow portion is attached to the head of an insulator provided with an optical fiber penetrating in the axial direction, and a current transformer for drawing an electric wire and a wire clamp are provided on the metal fitting, and the hollow portion is provided. The first and second photosensors each having an electro-optical element having a Pockels effect are housed in the current transformer, and a resistor for converting a secondary current from an electric line into a voltage signal is connected in parallel to the current transformer. Is connected to the first optical sensor, and the metal fitting is connected to the metal fitting and the insulator. The second optical sensor is connected in parallel with a capacitor that is sandwiched between the second optical sensor and the end face of the optical fiber, and each optical sensor is connected to the second optical sensor. Connected to one end of
A configuration is adopted in which the other end of the optical fiber is connected to the optical transmission line.

(Operation) This invention operates as follows by adopting the above means.

A current transformer and an electric wire clamp are provided on the power-supply-side metal fitting attached to the head of the insulator to hold the electric wire, and the first and second light beams are placed in the cavity of the power-supply-side metal fitting close to the electric wire. Since the sensor is positioned and stored, the output of the optical signal is stable.

Further, since the detection signal system path by the optical sensor is provided in the insulator that insulates and supports the electric wire, the failure of induction and insulation deterioration to the detection system path is prevented, and the current signal from one detection unit is used. Since the voltage signals can be detected at the same time, the facility space can be reduced.

Furthermore, since each phase current is changed to a voltage signal and applied to the photosensor having the Pockels effect,
The current and voltage can be detected by one type of optical sensor, and it is not particularly necessary to use two types of optical sensors separately, so that the assembly of the voltage detecting unit becomes simple.

(Embodiment) Hereinafter, an embodiment embodying the present invention will be described in detail with reference to FIGS. 1 and 2.

As shown in FIG. 1, the insulators 5A to 5C that insulate and support the three-phase electric line have the phase wires 4A to 4C respectively attached to the heads of the insulators 5A to 5C. Sink CT1-C
The current transformers CT1 to CT3, which are inserted through T3, are provided on the metal fitting on the charging side, which will be described later.

Each of the insulators 5A to 5C further constitutes a power detection unit as follows. A metal-side metal fitting 9 constituting a power-supplying unit is fixed to the upper end of a magnetic insulator main body 8 which is formed into a predetermined shape and size and fired, with cement 11, and a ground-side metal fitting 10 is attached to the lower end.
Are similarly fixed with cement 11. In each insulator body 8, two sets of two optical fibers 12 are integrally provided by penetrating the central portion in the axial direction to form an optical transmission line, and each optical fiber 12 is polarized. Wavefront preserving optical fiber.

The insulator 9 of each insulator is provided with a cavity 9a, and the first optical sensors 13A to 13C and the resistor connected to the upper ends of the pair of optical fibers 12 and 12 are provided in the cavity 9a. R1 is stored. The optical sensors 13A to 13C are voltage sensors having the Pockels effect and including electro-optical elements. The optical sensors 13A to 13C and the resistor R1 are connected in parallel to the current transformers CT1 to CT3 by the lead wires 15 and 15, and the electric currents of the electric wires 4A to 4C detected by the current transformers CT1 to CT3 are detected. , The resistor R1. The voltage across the resistor R1 is applied to the first photosensors 13A to 13C. The lower ends of the optical fibers 12 and 12 are connected to the optical connectors 16 mounted on the grounding side metal fittings 10, respectively,
The current detection system path of the power detection unit is configured by the above.

As shown in FIG. 2, the optical connector 16 is connected in series by the same polarization-maintaining optical fiber cables 17 to 20 as an optical transmission line. And each of the insulators 5A to 5C
Optical fibers 12, 12, optical sensors 13A to 13C,
The external optical fiber cables 17 to 20 are connected in series to form a continuous optical transmission line.

One end of the optical fiber cable 17 has a polarizing plate and a 1/4
A polarizer 21 made of a wave plate is connected, and a light emitting element 22 made of a light emitting diode is optically connected to the polarizer 21. The polarizing element 21 and the light emitting element 22 constitute a light emitting portion, and reference numeral 26 in the drawing denotes a power source. Then, the optical power emitted from the light emitting unit is made incident on the optical fiber cable 20. In addition,
If the light emitting unit uses a laser diode that emits linearly polarized light, the SN ratio can be improved, and the polarizer 21 can be omitted.

Also, an analyzer 23 is provided at one end of the fiber cable 17.
, And a light receiving element 24 formed of a photodiode is optically connected to the analyzer 23. The analyzer 23 and the light receiving element 24 constitute a light receiving portion. Then, the optical power passing through the optical transmission line is introduced from the optical fiber cable 17 to the light receiving element 24 via the analyzer 23, and reference numeral 27 in the figure is an amplifier.

The light emitting unit and the light receiving unit of this embodiment are housed in predetermined boxes 25, respectively. This box 25
Is installed anywhere on the electrical line.

Next, the operation of the current detection system path configured as described above will be explained based on FIG. 2 showing the principle equivalent to FIG.

Now, assuming that the current flowing through each of the electric wires 4A to 4C is a primary current, a secondary current is passed through each of the current transformers CT1 to CT3 by the action of the magnetic field around each of the electric wires 4A to 4C by the primary current. It is made to flow to each resistor R1 via the lines 15 and 15. Then, the voltage applied to both ends of each resistor R1 is
It is applied to each of the optical sensors 13A to 13C.

At this time, when the power supply 26 is operated, the light emitting element 22 is operated and optical power is emitted. The optical power is transmitted to the optical sensor 13C via the optical fiber cable 20 and the optical fiber 12 in the direction of the arrow without electromagnetic induction from the outside. The optical power is a change in voltage applied to the optical sensor C due to the Pockels effect of the optical sensor C.
That is, the phase is modulated according to the change in the current of the electric wire 4C.

Next, the optical power is transmitted to the optical sensor 13B through the optical fiber 12, the optical fiber cable 19, and the optical fiber 12 in the direction of the arrow without receiving electromagnetic induction from the outside. Then, similarly to the above, the optical sensor 13B
The phase is modulated according to the voltage change applied to the wire, that is, the current change of the electric wire 4B.

Further, the optical power transmitted in the arrow direction via the optical fiber 12, the optical fiber cable 18, and the optical fiber 12 is introduced into the optical sensor 13A. Here, the optical sensor 1
The optical power that has undergone the final phase modulation according to the voltage change (current change of the electric wire 4A) applied to 3A is the optical fiber 1
2. Transmitted to the analyzer 23 in the direction of the arrow through the optical fiber cable 17 in the direction of the arrow without being subjected to electromagnetic induction from the outside, and the intensity is modulated. In the optical power transmitted to the analyzer 23, the currents of the three-phase electric wires 4A to 4C are vector-wise combined. That is, the phase is modulated in proportion to the zero-phase current. This optical power is subsequently introduced into the light receiving element 24 and converted into an electric signal.

After that, the electric signal is amplified by the amplifying unit 27 and is output from the output terminals 28A and 28A. By connecting a predetermined meter to the output terminals 28A and 28A, zero-phase current Changes can be easily detected and measured.

Such a zero-phase current normally shows a zero value, but when a line fault occurs, it becomes a value other than zero. Therefore, the presence or absence of a line fault can be detected by detecting and measuring this change in the zero-phase current.

Next, the voltage detection system path in the power detection unit will be described. The same members as those of the current detection system path are designated by the same reference numerals and the description thereof will be omitted.

An electric wire clamp metal fitting 29, which holds the electric wires 4A to 4C and is electrically connected to the electric wires 4A to 4C, is connected to one end of the capacitor C1 via a conductive spacer 30a in the hollow portion 9a of the electric power charging side metal fitting 9. The other end of the capacitor C1 is in contact with the upper end surface of the insulator main body 8 through the conductive spacer 30b, and is attached between the power-imparting side metal member 9 and the insulator main body 8. Then, the second photosensors 13A to 13C similarly equipped with electro-optical elements are connected in parallel to the conductive spacers 30a and 30b at both ends of the capacitor C1.

The voltage detection system configured as described above also includes the second
As shown in the figure, they are connected according to the equivalent principle. In addition, C2 in the figure indicates the capacitance of the insulator body 8 itself.

Next, the operation of the voltage detection system will be described.

Now, the voltage of each electric wire 4A to 4C is applied to each capacitor C1 via the electric wire clamp 29 and the conductive spacer 30a,
The voltage across the capacitor C1 is applied to each optical sensor 13A.
Applied to ~ 13C.

When the power supply 26 is operated, the light emitting element 22 is activated and optical power is emitted. The optical power is converted into linearly polarized light through the polarizer 21, and the optical fiber cable 17 and the optical fiber 1
2 is transmitted to the optical sensor 13A in the direction of the arrow without being subjected to electromagnetic induction from the outside. Optical power is element 1
By the Pockels effect of 3A, the phase is modulated according to the applied voltage change, that is, the voltage change of the electric wire 4A.
Next, the optical power is transmitted to the optical sensor 13B through the optical fiber 12, the optical fiber cable 18, and the optical fiber 12 in the direction of the arrow without receiving electromagnetic induction from the outside. Then, similarly to the above, the phase is modulated according to the voltage change applied to the optical sensor 13B, that is, the voltage change of the electric wire 4B.

Further, the optical power transmitted in the arrow direction via the optical fiber 12, the optical fiber cable 19, and the optical fiber 12 is introduced into the optical sensor 13C, where the optical sensor 13
In accordance with the voltage change applied to C, that is, the voltage change of the electric wire 4C, the final phase modulation is performed, and through the optical fiber 12 and the optical fiber cable 20, in the direction of the arrow without receiving electromagnetic induction from the outside. , Transmitted to the analyzer 23,
Converted to intensity modulation. The optical power transmitted to the analyzer 23 is a vector-combined voltage of the three-phase electric wires 4A to 4C, that is, a zero-phase voltage. This optical power is subsequently introduced into the light receiving element 24 and converted into an electric signal.

After that, if the electric signal is amplified through the amplifier 27 and is output from the output terminals 28B and 28B, the change in the zero-phase voltage can be easily detected and measured only by connecting a predetermined instrument. .

Such a zero-phase voltage normally shows a zero value, but when a line fault occurs, it shows a value other than zero. Therefore, the line fault can be detected by detecting and measuring the change in the zero-phase voltage.

In the embodiment, the first and second optical sensors 13A to 13C are housed in the charging side metal fitting 9 on the head of the insulator body 8, and both the optical sensors 13 are arranged in the axial direction of the central portion of the insulator body 8.
Two sets of optical fibers 12 and 12 corresponding to A to 13C are integrally fixed to the insulator body 8, and each optical fiber 12 is separately connected to both optical sensors 13A to 13C. There is.

Further, as shown in the equivalent principle in FIG. 2, output terminals 28A and 28A for detecting a zero-phase current and output terminals 28B and 28B for detecting a zero-phase voltage are separately provided.

According to the present invention, as described above, the zero-phase current and the zero-phase voltage can be simultaneously detected from one power detection unit, and the optical sensors 13A to
Electric wire 4 having 13C held by the electric wire clamp 29
Since it is positioned in the cavity 9a of the power-supply-side metal fitting 9 in the vicinity of A to 4C, is housed together, and further, an optical signal is led out through each optical fiber 12 in the insulator 8. Induction or insulation deterioration at the detection location is prevented and the output of the detection signal is stabilized.

Further, one type of optical sensor 13A having a Pockels effect is used.
Since the current and voltage can be detected by 13C,
There is no complexity of using optical sensors, and assembly is simple.

EFFECTS OF THE INVENTION The present invention reduces the facility space and stabilizes the detection signal by constructing a detection unit that can simultaneously detect a zero-phase current and a zero-phase voltage by using an insulator that electrically supports an electric wire. As a result, there is an effect of improving the reliability of system management in power supply.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment embodying the present invention, FIG. 2 is a circuit diagram showing the principle of FIG. 1, and FIGS. 3 and 4 are circuit diagrams showing the principle of a conventional example. 4A to 4c ... Electric wire, 8 ... Insulator main body, 9 ... Charging side metal fitting, 9a ... Cavity part, 10 ... Grounding metal fitting, 12 ... Optical fiber, 13A-14C ... Optical sensor, 21 ... ... Polarizer, 22 ... Light emitting element, 23 ... Analyzer, 24 ... Light receiving element, C1 ... Capacitor, CT1-CT3 ... Current transformer, R1 ... Resistor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-253880 (JP, A) JP-A-60-102566 (JP, A) JP-A-58-172557 (JP, A) JP-A55- 57153 (JP, A) JP 54-47689 (JP, A) Actual development Sho 52-70456 (JP, U) Japanese patent Sho 49-1231 (JP, B2) Actual public 44-7588 (JP, Y1)

Claims (1)

[Claims] 1. An optical transmission line formed by connecting a light emitting portion to one end portion and a light receiving portion to the other end portion, and connecting them in series to each other by connecting them in series to each other. In the zero-phase voltage detection device of the three-phase electric line provided with a separate individual voltage detection unit, the voltage detection unit, a plurality of optical fibers axially penetrating the cavity provided in the head of the insulator provided. A first current sensor and a second optical sensor having a Pockels effect electro-optical element are provided in the hollow portion by mounting a current-carrying side metal fitting having the current transformer and an electric wire clamp on the metal fitting. While storing
A resistor for converting a secondary current from an electric line into a voltage signal is connected in parallel to the current transformer, and the first photosensor is connected to the current transformer. , The capacitor is sandwiched between the metal fitting and the end face of the insulator to connect the second optical sensor in parallel with a capacitor for dividing the voltage of the electric line, and each optical sensor is connected to the insulator. (3) A zero-phase detection device for a three-phase electric line, which is connected to one end of each of the optical fibers, and the other end of the optical fiber is connected to the optical transmission line.