JPS604430B2 - Light guide for high voltage electrical equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light guide for high voltage electrical equipment for transmitting signals between a high voltage part and a low voltage part, such as ground potential.

Either converts the electrical signal from the high voltage part into an optical signal and transmits this optical signal to the ground side, or transmits the signal from the ground side as an optical signal to the high voltage part and converts it into an electrical signal at the high voltage part. In order to measure or detect the amount of electricity in electrical equipment in high-voltage parts, etc., and to control this, light guides are made of hundreds to thousands of ultra-fine translucent fibers of several microns, such as glass fibers. is used.

Examples of applications of light guides to high-voltage electrical equipment include optical signal type instrument converters that transmit electrical signals corresponding to the current or voltage of high-voltage circuits to the ground as optical signals, and direct connection of many thyristors. It is used for failure detection of thyristor valves, which are AC/DC converters for direct current power transmission configured in parallel connection, for voltage detection, for monitor circuits, and for gate control pulse transmission.

The present inventors used such a light guide of a predetermined length to
When a withstand voltage test was conducted in the atmosphere, it was found that corona was generated at a much lower voltage than when a single piece of glass equivalent to this fiber was tested with a withstand voltage in dry air.

After investigating the cause, it was found that fibrous glass easily adsorbs moisture on its surface, and this adsorbed moisture reduces the withstand voltage of the light guide.

Therefore, the present inventors conducted a withstand voltage test on a light guide immersed in sufficiently dehumidified transformer insulating oil and injected with this insulating oil under reduced pressure. However, no improvement in withstand voltage was obtained compared to when a single glass was tested in a similar medium.

Furthermore, if light guides that connect multiple high potential parts with different potentials and the ground are arranged in parallel taking into account these withstand voltages, partial discharge is likely to occur between adjacent light guides, and this tendency is Even if the guide length was increased with a sufficient margin, the problem could not be prevented.

Therefore, an object of the present invention is to improve the withstand voltage characteristics in the longitudinal direction of a light guide that guides and connects a high potential part and a low potential part.

In order to achieve this objective, the present invention forcibly applies a potential to one or more locations along the longitudinal direction of the light guide,
The electric potential distribution per unit length in the longitudinal direction of the light guide is approximately equalized.

Forcibly dividing the potential between the high potential part and the low potential part can be done by using a capacitance or a high resistance body provided between the two military positions.

Such a potential dividing means is effective in a light guide which connects one high potential part and the ground side potential, such as an optical signal type instrument transformer.

A preferred embodiment of the present invention is an AC/DC converter for direct current power transmission.

Such an AC/DC converter has a plurality of thyristor valves, for example, six in the case of a three-phase full-wave rectifier bridge, and each thyristor valve itself is configured in multiple stages with multiple stacks of thyristors. Each thyristor stack or stage has a different potential, and these different potentials can provide a desired potential to each light guide.

EMBODIMENT OF THE INVENTION Below, the present invention will be specifically explained using an example in which the present invention is applied to an AC/DC converter for DC power transmission. Figure 1 shows an example of a daily converter among AC/DC converters for DC power transmission, and the output of the DC side winding ID which is electromagnetically coupled to the AC side winding IA of the main converter 1 is 6.
The circuit configuration is shown in which a three-phase bridge using thyristor valves 3A to 3F converts the current into direct current.

As shown in FIG. 2, each thyristor valve 3 is constructed by, for example, stacking a plurality of thyristor stacks 4A and 4B in series to form a stage, and connecting each stage in series. Ru.

5A and 5B indicate the input end and output end of the thyristor valve 3, respectively.

6 is a photoelectric conversion device installed on the ground side in order to control the gate of the thyristor 7 of each thyristor stack 4. Optical signals from these photoelectric conversion devices 6 are transmitted via a light guide 8 to the thyristor 7 at a high potential. Photoelectric conversion device 9 installed on the side
There, the signal is converted into an electric signal to control the gate of each thyristor 7, thereby controlling the conduction of the thyristor.

Although not clearly shown in the drawings, all the thyristors 7 are provided with the thyristor ignition control device.

In addition, instead of providing the photoelectric conversion devices 6 and 9, the light guide 8, etc. for each thyristor 7, they are provided for each thyristor stack 4 unit, and signals are distributed from the photoelectric conversion device 9 to each thyristor. It's okay.

FIG. 3 shows a specific configuration example of a light guide corresponding to one thyristor bulb 3, and shows a case where the light guide is adapted to a five-stage configuration per one bulb.

The photoelectric conversion devices 10A to 108 on the ground side corresponding to the thyristor stack of each stage are housed in the storage box 11, and the photoelectric conversion devices 12A to 12E on the side of each stage are stored in insulating cylinders 13, 14, 15, 16, 17, respectively. They are housed in storage boxes 18, 19, 20, 21, and 22 that are insulated from each other via a.

22a indicates a shield provided on the top storage box 22 at the same potential.

Note that the insulating tube 13 is formed long enough to obtain a dielectric strength equivalent to ensuring ground insulation of the entire thyristor valve, while the other insulating tubes 14 to 17 ensure insulation between each thyristor stack. It is formed relatively short to the extent that it can be used.

The connecting portions of these storage boxes and insulating cylinders are made oil-tight, and the insides thereof are filled with an insulating medium such as electrical insulating oil.

23A to 238 are respective photoelectric conversion elements 10A to 10E and 12
A to 126 are light guides provided to form an optical path between each light guide 23 and each storage box 1.
1 ceiling surface 11a, bottom surface 18a of storage box 18, ceiling surface 1
8b, the lower surface 19a of the storage box 19 is penetrated through the holes provided on the bottom surfaces 20a, 21a, 22a of each storage box 20-22, such as the ceiling surface 19b, and the ceiling surfaces 20b, 21b.

Further, each photoelectric conversion element 12 is provided on the side of each storage box 18 to 22.
Finely insulated terminals 25A to 258 are provided for drawing out the lead wires 24 drawn out from A to 12E toward the thyristor stack. The photoelectric conversion device i2 corresponding to each stage is also provided in a divided manner corresponding to each thyristor stack or individual thyristor, as shown in FIG. 26 provides the necessary insulation. Therefore, each storage box 18
The potential adjustment electrodes 27 provided on the surfaces of the light guides 23 located within the light guides 23 and 21 are electrically connected to each other and set to the same potential as the storage box. Therefore, each adjacent light guide is made to have the same potential for each storage box, and as a result,
The corona starting voltage can be significantly increased without creating a potential difference between adjacent light guides.

In general, the ratio of glass that makes up a light guide is about 8, which is higher than that of SF6 insulating gas or insulating oil, which is 2 to 3, and the resistivity of glass is several orders of magnitude lower than that of insulating gas. By arranging a plurality of different light guides adjacent to each other and applying a high AC or DC voltage to both ends of these light guides at once, the potential distribution of the light guides can be made substantially uniform along the length direction.

For this reason, if a plurality of light guides with different lengths and different potentials are arranged all at once, a potential difference occurs between adjacent light guides, and this potential difference tends to cause partial discharge.

However, as in the above embodiment, each ride guide is
By forcing each light guide to have the same potential, the potential difference between adjacent light guides can be shared almost equally between each stage and between the lowest stage and the ground, reducing partial discharge. Helps to suppress. In order to provide each light guide potential, in the above embodiment, a herring-shaped electrode was provided on the surface of the light guide, but in the present invention, as shown in FIG. A conductive resin-impregnated portion 30 is formed to electrically connect most of the fibers 28 of the bundled light guide 29, and a conductive band 31 is provided thereon by winding a conductive tape. It can also be an electrode.

Furthermore, if necessary, as shown in FIG.
The outer surface of 1 may be covered with an insulating synthetic resin 32. According to such an embodiment, a potential can be forcibly applied to the inside of the light guide, and potential sharing among the light guides can be performed more reliably. In the above example, since each light guide is encased in an insulating medium such as insulating oil, it is possible to perform an insulation test on the pre-light guide alone, and perform the necessary tests before incorporating it into the converter. be able to.

In the above embodiments, the present invention was applied to a point fox of an AC/DC converter for DC power transmission, but in the present invention, a light emitting signal or an electric signal when a thyristor valve of the same converter fails. The same device can also be used for failure detection, which is transmitted as an optical signal to the ground, and for voltage detection and monitoring of each thyristor.

In addition, when using a light guide in an optical signal type instrument converter, by forcibly applying a potential to the middle, even if the length of the light guide does not match the required creepage insulation length, the potential is applied between the parts. The electric potential can be shared evenly, and the generation of corona caused by partial discharge can be suppressed.

In the above embodiments, a case has been described in which insulating oil is used as the insulating medium, but it is also possible to use a gaseous insulating medium such as SF6 gas, air, or nitrogen.

The present invention provides a light guide for transmitting optical signals between a high potential part and a low potential part as explained above in the embodiments, and forcibly adjusts the length of the light guide midway in the length direction. Since it is designed to apply a commensurate electric potential, it is possible to more evenly divide the electric potential in the length direction of the light guide, suppress corona generation due to partial discharge, and reduce the electrical dielectric strength of the light guide material itself to the limit value. It is possible to improve pressure resistance.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a DC power transmission converter using a thyristor valve, Fig. 2 is a circuit diagram showing the connection configuration side of the thyristor valve, and Fig. 3 is an embodiment of the light guide according to the present invention. 4 is a cross-sectional view taken along line W-W in FIG. 3, and FIGS. 5 and 6 are different embodiments of the means for applying potential to the light guide used in the present invention. FIG. Explanation of symbols, 10, 12...Photoelectric conversion device, 2
3,29...Light guide, 27...
Electrode, 28... Glass fiber material, 30... Conductive resin, 31... Conductive band. Multi figure hair z figure hair 4 figure hair 3 figure hair 5 figure *6 figure

Claims (1)

[Scope of Claims] 1. A first photoelectric conversion device that converts an electrical signal into an optical signal, and a second photoelectric conversion device that converts an optical signal into an electrical signal. One is installed in a high potential part of high voltage electrical equipment, the other is installed in a low potential part that is lower in potential than the high potential part, and a superfine transparent fiber material is used between the first and second photoelectric conversion devices. The light guide is connected by a light guide made up of a large number of bundled light guides, and this light guide is provided in a highly insulating electrically insulating medium. A light guide for high-voltage electric equipment, characterized in that the lengths of the light guiding paths from the low potential part to the high potential part are set at the same potential at midway positions. 2 It has a first photoelectric conversion device that converts an electrical signal into an optical signal, and a second photoelectric conversion device that converts an optical signal into an electrical signal, and one of the photoelectric conversion devices is a high-voltage electrical device. One photoelectric conversion device is installed in a high potential part, and the other is installed in a low potential part whose potential is lower than the high potential part, and between the first and second photoelectric conversion devices, a large number of ultra-thin transparent fiber materials are tied together. The light guide is arranged in a highly insulating electrically insulating medium, and the light guide has a plurality of high potentials whose absolute potential is gradually higher than the low potential part. A high potential light guide is characterized in that a plurality of light guides are arranged in parallel to form a light guide path to the section, and each of these light guides is provided with the high potential of each step at the portion located in the high potential section of each step. Light guide for voltage electrical equipment. 3 It has a first photoelectric conversion device that converts an electrical signal into an optical signal, and a second photoelectric conversion device that converts an optical signal into an electrical signal, and one of the photoelectric conversion devices is a high-voltage electrical device. One photoelectric conversion device is installed in a high potential part, and the other is installed in a low potential part whose potential is lower than the high potential part, and between the first and second photoelectric conversion devices, a large number of ultra-thin transparent fiber materials are tied together. In the structure, a plurality of the light guides are arranged in parallel, and a conductive resin is applied to the potential-applying part of the light guide. A light guide for high-voltage electrical equipment, characterized in that the transparent fiber materials in this part are electrically connected to each other.