JPH0249472B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase determination device that can determine whether phases at both ends of a certain section of a distribution line match in a live line state.

Conventionally, each phase, which is displayed in different colors at both ends of a distribution line section, is determined by the phase order (or phase rotation) at that terminal for each terminal. phase, red phase,
The white phase corresponds to the color-coded display on the other end (receiving side), that is, black phase, red phase, and white phase, but the black phase on one end side, the black phase on the other end side, and the red phase on one end side match. There were cases in which the phase and the red phase on the other end side did not necessarily match, and the white phase on one end side and the white phase on the other end side did not necessarily match.
However, when operating a power distribution line, there are cases where it is desired to determine the color-coded display at the other end in accordance with the color-coded display at one end, that is, the black, red, and white phases, and a phase discrimination device is required for this purpose.

Conventionally, this type of phase discrimination device has been used when no voltage is applied to the distribution line (dead line), as shown in Figure 1.
For example, insert resistors R ₁ , R ₂ , and R ₃ with different resistance values into each phase at the other end (receiving side), and measure the resistance value of each phase with a resistance meter R at one end (transmitting side). By measuring, a phase in which the resistance values of the phases at both ends are the same is detected and phase discrimination is performed.

However, such a phase determination device is complicated because it requires the power transmission line to be temporarily stopped in order to perform phase determination, and it also requires information exchange between both ends to confirm the resistance value. In addition, in order to perform phase discrimination, the coating of the distribution line is removed and the resistance R ₁ ,
The work was time-consuming because R ₂ and R ₃ had to be connected and grounding had to be established as well.

In view of the above, the present invention has been developed to keep the distribution line live,
It is an object of the present invention to provide a phase discrimination device which is capable of phase discrimination using only information on one end of the phase discrimination, and does not require time-consuming work on the other end (receiving side) for discrimination. .

Next, embodiments of the present invention will be described in detail based on the drawings.

Figure 2 shows how to determine which phase of the black, red, and white phases at point A (on the transmitting side) match the phases at point B (on the receiving side) between A and B in a certain section of the distribution line. An example is shown. In FIG. 2, reference numeral 1 denotes a voltage transformer that takes out a specific phase voltage (eg, black phase voltage). Output a of voltage transformer 1
(see FIG. 3) is given to the waveform shaping circuit 2,
Shaped into a rectangular wave. The output b of the waveform shaping circuit 2 and the output c of the measurement signal generator 3 are given to a synchronization circuit 4, and the measurement signal d is synchronized with a specific phase (for example, 0°) of the phase voltage of the output of the waveform shaping circuit 2. is output. The output d of the synchronous circuit 4 is given to the signal combiner 5 and superimposed on the phase voltage (black phase voltage). The black phase voltage on which the measurement signal d is superimposed is shown by a waveform diagram e in FIG. Therefore, the voltage transformer 1, the waveform shaping circuit 2, the measurement signal generator 3, the synchronization circuit 4, and the signal combiner 5 constitute a measurement signal generation device.

At point B (receiving side) where phase discrimination is performed,
A measurement signal detection device is provided which includes an electric field sensor 6, a signal voltage separation circuit 7, a waveform shaping circuit 8, and a phase discrimination circuit 9, which will be described below. The electric field sensor 6 has one detection section, and by sequentially installing this detection section in the electric field of each phase, it sequentially measures each phase, and outputs a detection signal according to the phase of the electric field. .

The structure and principle of the electric field sensor 6 will be explained based on FIGS. 4 to 7. FIG. 4 is a diagram explaining the principle of the electric field sensor 6, in which an electric field E is applied to an electro-optic crystal 10 having a Pockels effect. For example, LiNbo ₃ is used as the electro-optic crystal 10. The incident light is linearly polarized through a polarizer 11 and then applied to an electro-optic crystal 10 . When this linearly polarized light is incident on the electro-optic crystal 10, light in this vibration direction cannot exist, and it is split into two light waves that are perpendicular to each other. One light wave is an electro-optic crystal 10
When an electric field is applied to
L ₁ ), the other light wave becomes slower (slow wave L ₂ ).
Therefore, when light is emitted from the output surface of the crystal 10, a phase difference Γ occurs between the light whose vibration is in the vertical direction and the light whose vibration is in the horizontal direction. Therefore, the composite vector diagram of the emitted light becomes an ellipse, a circle, or a straight line depending on the phase difference Γ, as shown in FIG. In Figure 5, A is Γ=0, B is 0<Γ<π/2, C is Γ=π/2, and D is π/2<Γ<
π and ho indicate the state when Γ=π. This phase difference Γ is expressed by the following equation.

Γ=hlv/d...(1) However, in equation (1), h is the proportionality constant and l is the crystal 10
d is the thickness of the crystal 10, and v is the voltage applied to the crystal. As is clear from equation (1), the phase difference Γ is proportional to the voltage V applied to the crystal, that is, E (=v/d). This phenomenon is well known as the Pockels effect or first-order electro-optic effect. The light emitted from the electro-optic crystal 10 is passed through a quarter-wave plate 12 to which a phase difference Γ _R =π/2 is added, and then passed through an analyzer 13 to select only the components in the oblique direction (45° to the horizontal direction). . This selected light intensity I is I=sin ² (Γ/2+π/4) ...(2), and since the phase difference Γ is proportional to the voltage V applied to the electro-optic crystal 10, the light intensity I and the voltage V show changes as shown in FIG. Therefore, the voltage V
is given by V=V0sin wt, the light intensity I is the 7th
As shown in the figure, when the light is modulated by the voltage V and Vo is small, the light intensity I can also be approximated as a sine wave. Therefore, the voltage can be detected by converting the light selected by the analyzer 13 into an electrical signal.

FIG. 8 shows a configuration diagram of an electric field sensor 6 using an electro-optic crystal as described above, and includes an electro-optic crystal 10, a polarizer 11, a wavelength plate 12, an analyzer 13 as shown in FIG. It consists of a detection unit 14, optical fibers 15 and 16, an electrical-to-optical converter 17, and an optical-to-electrical converter 18. The detection unit 14 is installed at a position that is affected by the electric field around the distribution line, and the output of the Koichi electric converter 18 is subjected to signal processing such as amplification and then input to the signal voltage separation circuit 7 shown in FIG. be done.

The operation of the measurement signal generator shown in FIG.
The explanation will be based on the waveform diagram shown in the figure. As shown in Fig. 9, each phase voltage U ₁ , V ₁ , W ₁ has a measurement signal d.
are superimposed. Note that although the measurement signal d is superimposed on only one phase of the black phase voltage at point A (transmission side), three phase voltages U ₁ , V ₁ , and W ₁ are superimposed at point B (reception side). The measurement signal d is superimposed, but this is mainly due to a wrap-around phenomenon on the power supply side through the distribution transformer. Of course, this measurement signal d may be superimposed on all three phases: black phase, red phase, and white phase.

The electric field sensor 6 converts light modulated by an electric field caused by the phase voltage of the installed phase into an electric signal and outputs the electric signal. The output of this electric field sensor 6 is given to a signal voltage separation circuit 7. This signal voltage separation circuit 7 has a filter for extracting a measurement signal, and outputs a measurement signal X ₁ and a signal X ₂ based on the phase voltage. The phase of this signal X ₂ differs by 120° depending on which phase the electric field sensor 6 is installed. These signals X ₁ and X ₂ are applied to the waveform shaping circuit 8. The waveform shaping circuit 8 is composed of a single constant multivibrator that generates an output pulse each time the waveform of the signal X ₂ crosses 0°, for example, and terminates the pulse after 120° has passed, for example. The output signal X ₃ of this monostable multivibrator is the electric field sensor 6
The signals U ₂ , V ₂ , and
It will look like W ₂ . The measurement signal X ₂ is also taken out by another monostable multivibrator, and the output signals X ₃ and X ₄ of the waveform shaping circuit 8 which outputs the signal X ₃ shown in FIG. 9 are given to the phase discrimination circuit 9. . This phase discrimination circuit 9 is composed of, for example, an AND circuit that receives signals X ₃ and X ₄ as inputs. As can be understood from FIG. 9, when the electric field sensor 6 is installed in the U phase, an output signal is output from this AND circuit. Therefore,
It can be seen that this U phase corresponds to the black phase at point A (transmission side). This phase determination circuit 9 detects synchronization between the measurement signal and each phase voltage at point B, and the phase synchronized with the measurement signal matches the specific phase at point A.

On the other hand, since the phase rotation direction at point B can be determined by known means, the other two phases at point B can be easily determined.

If the phase rotation is unknown, rotate the measurement signal X ₃ every 120 degrees at point B (that is, delay it by 120 degrees with a delay element), and detect the phase voltages that are synchronized with each signal X ₃ . By doing so, it is possible to distinguish between the other two phases. That is, if the measurement signal X ₃ is delayed by 120°, it will be synchronized with the signal V ₂ , and if it is delayed by a further 120°, it will be synchronized with W ₂ .

The conventional method for detecting signals superimposed on distribution lines is to use a voltage divider that places electrodes on the coating of the distribution line and uses the capacitance between them. This causes a change in the phase of the voltage divider, so when applied to phase discrimination, it is not only difficult to accurately detect the phase voltage waveform, but also requires grounding, which complicates the work. In contrast, in the present invention, a detection section made of an electro-optic crystal is installed in an electric field formed around the distribution line or in the surrounding space, and the phase voltage waveform is detected based on the electric field. Although the electric field strength varies depending on location, the phase of the electric field is independent of location and matches the phase of the voltage on the distribution line. Therefore, it is possible to detect a phase voltage waveform with an accurate phase regardless of the installation location of the detection section made of an electro-optic crystal. Furthermore, since phase voltage waveforms can be detected simply by installing the detection section around the distribution line or in the electric field in the surrounding space, the effort of installing and grounding the detection section can be saved. Furthermore, since the detection unit and the power distribution line may be in non-contact, and a highly insulating optical fiber is used for optical signal transmission, detection with high electrical insulation is possible with less risk of electric shock. Then, information is not exchanged between both ends of the distribution line section,
In addition, it is possible to determine the phase matching the phase at one end at the other end while the wire remains live.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional phase discrimination device, Figure 2 is a block diagram of a conventional phase discrimination device.
The figure is a block diagram showing an example of the phase discrimination device according to the present invention, and FIGS. 3 and 9 are waveform diagrams showing the output waveforms of some of the components in FIG. 2, respectively.
Figure 4 is a diagram explaining the principle of electro-optic crystal, Figure 5 is a composite vector diagram of the light emitted from the electro-optic crystal, and Figure 6 is a diagram explaining the principle of electro-optic crystal.
7 is a diagram for explaining the modulation of the light intensity I, and FIG. 8 is a block diagram showing the configuration of the electric field sensor. 1... Voltage transformer, 2... Waveform shaping circuit, 3...
...Measurement signal generator, 4...Synchronization circuit, 5...Signal coupler, 6...Electric field sensor, 7...Signal voltage separation circuit, 8...Waveform shaping circuit, 9...Phase discrimination circuit, 10... ...Electro-optic crystal, 11...Polarizer, 1
2... Wave plate, 13... Analyzer, 14... Detection section, 15, 16... Optical fiber, 17... Electric-to-optical converter, 18... Optical-to-electrical converter.

Claims (1)

[Claims] 1 Installed at one end (transmission side) of the distribution line section,
A measurement signal generator that superimposes a measurement signal of a specific frequency on the distribution line in synchronization with the phase voltage of a specific phase on one end, and a measurement signal generator that superimposes a measurement signal of a specific frequency on the distribution line on the other end (receiving side) or in the surrounding space. a detection section made of an electro-optic crystal having a Pockels effect installed in the formed electric field; and detection for detecting the measurement signal and the phase voltage waveform from an optical signal that passes through the detection section and is modulated by the electric field. and a determining means for determining a phase on the other end side that corresponds to a certain specific phase on the one end side based on the detection result of the detecting means.