JPS59128454A - Potential transformer - Google Patents

Abstract

PURPOSE:To realize a small high voltage and high preciseness transformer reduced in a heat generating amount, by a method wherein light applied electric field sensors are arranged at almost equal intervals to an electric field to be measured and the sum total obtained after the light outputs thereof are subjected to photoelectric conversion is used as the secondary output of the transformer. CONSTITUTION:Light applied electric field sensors 151-15n are attached to the interior of the support member 13 provided between a primary terminal 11 and an earth part 12 at almost equal intervals. An electric field detecting apparatus 18 consisting of the sensors, an optical fibers 16 and a photoelectric converter 17 receives modulation corresponding to the size of an electric field E acting on the sensor 15 when the light from a light emitting part 19 passes the sensor 15 and the light to be modulated is demodulated while introduced into a light receiving part 20 to be supplied to a signal treating part 21. In this case, the secondary output of a transformer is obtained by adding the output of each photoelectric converter 17 corresponding to each sensor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a voltage transformer, and particularly to a voltage transformer that measures high voltage with high precision.

[Technical background of the invention and its problems]

Conventionally, a capacitor voltage divider 1' was used to measure high voltage.
, some use a resistive voltage divider. Potential transformers using capacitor voltage dividers are applied to voltage classes above 154 kV, primarily because they are also lower in cost than wound type potential transformers.

Potential transformers using resistive voltage dividers are used as DC potential transformers. FIG. 1 shows a schematic configuration diagram of a conventional potential transformer using a capacitor voltage divider or a resistor voltage divider. In FIG. 1, a high voltage side impedance (2) and a low voltage side impedance (3) are connected in series between a negative terminal (1) and a ground (8) to form a voltage divider. Although not particularly shown, if the voltage divider is a capacitor voltage divider, it is composed of capacitance, and if it is a resistive voltage divider, it is composed of resistance. A transformer (4) is connected to both ends of the low voltage side impedance (3), and this transformer (4) is a resonant handle when it is a capacitor-type instrument transformer, and a DC instrument transformer when it is a resistive voltage divider. This is a DC amplifier that makes up a transformer. Furthermore, metamorphosis device (4)
are provided with secondary terminals (5a) and (5b), and a secondary voltage v2 appears between the secondary terminals (5a) and (5b). There is an insulation resistance (6) or stray capacitance (7) between the high voltage side impedance (2) and the potential of the ground (8). Although this insulation resistance (6) and stray capacitance (force) actually exist as distributed constants, they are shown as lumped constants in FIG. 1 for convenience of explanation.

Insulation resistance (6) is, for example, high voltage side impedance (2)
The stray capacitance (the force is determined by the supporting member, the dielectric constant of the insulating medium, and the impedance on the high voltage side (the shape of the two, the distance between the ground, etc.) and is always present. It is something.

By the way, insulation resistance (6) and stray capacitance (power) vary greatly depending on factors such as temperature, humidity, pollution, and aging.

Furthermore, the insulation resistance (6) is generally non-linear with respect to voltage. In order to prevent such changes in insulation resistance (6) and stray capacitance (7) from affecting the error characteristics of the instrument transformer, the high voltage side impedance (2) is It is selected to be sufficiently small compared to the impedance. By designing the high voltage side impedance (2) to be sufficiently small, the relationship between the - secondary voltage V and the secondary voltage ) and stray capacitance (potential transformer that is not affected by force can be obtained. Here, Z is the impedance value of the high voltage side impedance (2), Z
2 is the impedance value of the low voltage side impedance (2), and K is the transfer function of the transformer (4), which is constant.

However, making the high voltage side impedance (2) sufficiently small means the following.

(1) If the high voltage side impedance (2) is a capacitance, the capacitance must be increased. In order to secure the necessary cutting force performance and increase capacitance,
There is a limit to the means of reducing the distance between the electrodes, and the only option is to increase the opposing area of the electrodes.

This will lead to an increase in the size of the tamashi equipment.

(ii) If the high voltage side impedance (2) is a resistance, the resistance value must be made small. The smaller the resistance value, the more heat is generated, and a large cooling device must be attached. Furthermore, since the amount of heat generated is proportional to the square of the voltage and inversely proportional to the resistance value, the higher the voltage, the more consideration must be given to heat radiation measures.

As described above, conventional high-voltage, high-precision voltage transformers are large in size, and DC voltage transformers that use resistive voltage dividers in particular have the problem of generating a large amount of heat.

[Purpose of the invention]

The invention has been made in consideration of the above points, and its purpose is to provide a compact, high-voltage, high-precision voltage transformer that generates a small amount of heat.

[Summary of the invention]

In order to achieve such an object, the present invention provides a primary terminal to which a constant voltage υ1j is applied, and a plurality of terminals arranged at selected intervals in an electric field generated between this secondary terminal and a ground potential section. a first group of optical fibers that guide light to these optical electric field sensors, a second group of optical fibers that transmit the light that has passed through the optical electric field sensor, and each of the first optical fibers. a plurality of light emitting sections that supply light to the fiber groups; a plurality of light receiving sections that receive light guided by each second optical fiber group; 1. It consists of a plurality of signal processing sections that input the output signals of each light receiving section, and an adder that adds the outputs of each signal processing section, and by using the output of this adder as a secondary output, it is possible to The feature is to obtain a high-voltage, high-precision instrument transformer that generates a small amount of heat.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A voltage transformer according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, a support member (13) such as an insulating tube is provided between the primary terminal αυ whose end is rounded and the ground potential part (1).Inside the support member (13), for example, A plurality of optical electric field sensors (151), (152), consisting of a polarizer, a Pockels element, and an analyzer.
(153) + .

Optical electric field sensor (one type is optical electric field sensor (tS) as shown in Fig. 3).
), an electric field detection device (18) is constituted by the photoelectric converter α power connected to the photoelectric converter α power. The photoelectric converter α power is connected to the light emitting part α9) connected to the optical fiber (16a) and the optical fiber (1
6b) and a signal processing section (21) connected thereto.

The operation of the electric field detection device (181) is as follows.The light from the light emitting part d is transmitted through the optical fiber (16a) and guided to the optical electric field sensor (L!19).
15) is modulated according to the magnitude of the electric field E acting thereon. The modulated light is transmitted through an optical fiber (16b
) is guided to the light receiving section (20), where it is demodulated as an electrical signal, further processed by the signal processing section (2υ), and then output.

FIG. 4 is a block diagram showing the addition of electric field values detected by each optical electric field sensor (151), (152), . . . , (15n) serving as the secondary output of the instrument transformer. Each optical electric field sensor (151), (152) shown in FIG.
, (15n) are the respective optical fibers (16a+), (16a2), , -, , (16a) as shown in FIG.
n), (16b1), (,16b2), −, , (1
6bn) and each electrical converter (i7i) on the ground potential side,
(Ty2), . . . (x'; rn), each electric field detection device (181), (182).

..., (18n), each photoelectric converter (1
7s).

(172), ..., (17n) to the adder (2
By adding in step 2), the secondary output of the potential transformer is obtained.

In the configurations shown in FIGS. 2 and 4, the -order terminal (1
When voltage V is applied to 7), each optical electric field sensor (
151)t(152)1. , , , (15n) are placed in the vicinity of the electric fields El, E2 . ...When TEn, each optical applied electric field sensor (15+), (152), -
, (15n), each photoelectric converter (1
71), (172), -, (17n) output y, ,
y2. , , Vn is proportional to each electric field, so the following formula % Formula % Here, k is a proportionality constant.

Therefore, the output VI of adder e2 is large (that is, Δl is small) (in the case of +; +:
) The equation becomes - fiii) The integral on the right side of the equation is the definition of voltage itself, and is. Therefore, from equation (iii) and (+v), v = k・v■(vll What can be obtained ■ Note that the optical electric field sensor is placed in a high voltage section, but since the optical fiber is a good insulating material, it is connected using this optical fiber, so there is no problem in terms of withstand voltage. Needless to say, there is no such thing.

What should be noted here is that equation (iv) holds true regardless of the intermediate integration path or electric field distribution once the positions and potentials of the starting and ending points of the integral path l are determined.

This shows that even if the electric field distribution changes due to changes in stray capacitance or insulation resistance, it does not affect the secondary output of the potential transformer. In other words, there is no need for a dedicated large capacitor voltage divider or a low resistance voltage divider that generates a large amount of heat as in conventional voltage transformers, so it is possible to create a high voltage, high precision voltage transformer that is small and generates little heat. is obtained.

〔Effect of the invention〕

As explained above, according to the voltage transformer of the present invention,
A plurality of optical electric field sensors are arranged at approximately equal intervals in an electric field to which a voltage to be measured is applied, and the sum of the outputs of each photoelectric converter that receives the optical output of these optical electric field sensors is converted to an instrument transformer. To provide a high-voltage, high-precision instrument transformer that is small, generates little heat, and is not affected by changes in electric field distribution due to changes in stray capacitance or insulation resistance due to secondary output. be able to.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional voltage transformer, Fig. 2 is a schematic diagram of a voltage transformer of the present invention, and Fig. 3 is a block diagram of the electric field detection device shown in Fig. 2. FIG. 2 is a block diagram showing the addition of output voltages in each electric field detection device that is the output of the voltage transformer of the invention. α1) - next terminal, (12+... ground potential part, (I3)... support member, 05), (15+), (1s2), -, (15n),
, , Optical electric field sensor, (16a) , (i6at)
, −, (16an), (16b), (16b+)
, (16bz). ..., (16bn) ... optical fiber, (17), (1
71), (172), -, (17n) -Photoelectric converter, 0ne, (181), (182),..., (18n)
... electric field detection device, tI wing... light emitting part,
(20... light receiving section, (21) signal processing section, (2
21・Adder, Agent Patent Attorney Inoue-M Figure 1 Figure 3 Figure 8 t-Dt'7 Figure 2

Claims (1)

[Claims] A primary terminal to which a voltage to be measured is applied, a plurality of optical electric field sensors arranged at selected intervals in an electric field generated between this secondary terminal and a ground potential part, and these optical electric field sensors. a first optical fiber group that guides light to the optical fiber sensor, a second optical fiber group that transmits the light that has passed through the optical electric field sensor, and a plurality of light emitting units that supply light to each of the first optical fiber groups. a plurality of light receiving sections that receive the light guided by the second fiber group, a plurality of signal processing sections that receive the output signals of the respective light receiving sections, and an output of each of the signal processing sections. An instrument transformer characterized in that it includes an adder for addition, and the output of the adder is used as a secondary output.