JPS6178084A - Arrestor for ac-dc converter station - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to an improvement of a lightning arrester for an AC/DC converter station which is inserted between the DC side winding of a converter transformer in the AC/DC converter station and the ground.

[Technical background of the invention and its problems 1 In recent years, electric power systems have been trending toward higher power consumption, and when transmitting large amounts of power to remote locations, the transmission voltage increases in DC power transmission as well as in AC power transmission. Already ±250kv in 82 countries
A class AC/DC converter station has been constructed. For example, 10000
For M to V class power transmission, AC power transmission is treated as UHV (
Voltage of 1000kV or higher) is essential, but 1JH
When it comes to Vl&, a huge amount of site space is required to secure space during the lowering of the transmission tower, which is disadvantageous. On the other hand, in the case of DC power transmission, sufficient power transmission capacity can be provided at 500 kV, and insulation equivalent to 500 kV AC can be used, so there are many advantages.

Now, the conventional AC/DC converter station in our country is =250k
Equipment layout is determined based on air insulation up to class V. However, if a converter station capable of handling ±500 kV was designed as an extension of this technology, the site for the converter station would be enormous. In order to deal with this, the calculation of switchgear such as circuit breakers and new circuit switches or lightning arresters is
There is a trend toward adopting gas-insulated containers that can be made larger and smaller in size.

Gas-insulated equipment, for example M lightning equipment, is one in which an insulating gas (for example, SF6 gas) is sealed in a grounded tank containing a built-in non-linear resistor stacked in multiple stages.
It has a configuration without an i-output part.

Now, when an AC/DC converter station is constructed, a large number of lightning arresters are required as shown in Figure 3.

, Fig. 3 shows the connections of the AC/DC converter station, where 1 is the high voltage stage converter transformer for the upper bridge, 2 is the low voltage stage converter transformer for the lower bridge, and the AC/DC converters 3 and 4 are connected to each other.
connected to charge the battery. The voltage rectified by the AC/DC converter 3.4 has ripples absorbed by the DC reactor 5, becomes a flat voltage, and is sent to the DC line 6.

Here, the protection 11ffi includes a surge arrester 7.8 inserted between the windings of the transformers 1 and 2, and a ground surge arrester 9.10 inserted between the transformer windings and the ground. For example, in the case of the sophisticated two-stage bridge shown in FIG. 3, the number of line-to-line lightning arresters 7.8 and ground-to-ground lightning arresters 9 and 10 is for a total of 12 phases. This number is
This is 6 times the number of bridges n. As the DC transmission voltage increases, the number of bridges in the AC/DC converter tends to increase, and the number of lightning arresters increases accordingly. Since an increase in the number of M lightning arresters used leads to an increase in the installation area and cost of the AC/DC converter station, it is desirable to reduce the number of lightning arresters used.

[Object of the Invention] The present invention has been made to meet the above-mentioned needs, and is intended to reduce the number of lightning arresters used in an AC/DC converter station, thereby reducing the size of the AC/DC converter station and reducing costs. The purpose is to obtain the local M lightning device.

[Summary of the Invention] In order to achieve the above object, the present invention provides a lightning protection device inserted between each phase of the DC side winding of a transformer for a high voltage stage and a low voltage stage in an AC/DC conversion station and the ground. , one phase of the lightning arrester is used as a lightning arrester for each of the high-voltage stage conversion transformer and the low-voltage stage conversion transformer, and one phase of the high-voltage stage conversion transformer is connected to the top of the lightning arrester. , one phase of the low voltage stage conversion transformer is connected to the lower part of the middle stage via a gap device.

[Embodiments of the Invention] Hereinafter, an embodiment of the lightning arrester of the present invention will be described with reference to the drawings. In the present invention, one phase each of the high-voltage stage bridge surge arrester and the low-voltage stage bridge surge arrester is used as one surge arrester, which is shown in FIG. For convenience, FIG. 1 shows only one phase of each of the upper and lower bridges.

The thyristor valve 15 constituting the AC/DC converter is housed in the valve hole 13, and the AC/DC converter and the converter transformer are electrically and mechanically connected to the gas insulated pipe bus l1i.
112a. In order to prevent space loss, the pipeline busbars 12a of each phase are arranged so as to be stacked in the height direction as shown in the figure. A gas insulated conduit bus 12b branched from this gas insulated conduit bus 12a is coupled to the illumination device 16. This 11 lightning device 16 has an internal element 16a in which non-linear resistance elements are stacked in multiple stages, and a tank 16 filled with SFs gas.
b. Of the gas-insulated pipeline busbars 12a and 12b, which are constructed by storing a high-voltage conductor together with an insulating gas in a pipeline, the gas-insulated pipeline busbar 12b is for the upper bridge of the thyristor valve 15 i! ! The lightning arrester 16 is connected to the top of the lightning arrester 16, and the lower bridge is connected to the portion below the middle stage of the lightning arrester 16. Details of the area around the lightning arrester 16 are shown in FIG. In FIG. 2, the high voltage conductor 17 for the upper bridge is connected to the non-linear resistance element 1 through an insulating spacer 18.
6a. One high voltage conductor for the lower bridge has a separation gap 20. Through the insulating spacer 21,
It is connected to a portion below the middle stage of the non-linear resistance element 16a. This middle stage refers to the element that is located at the center of the stack in the axial direction. In addition, the non-linear resistance element 16a insulating spacer 18,
21. A tank filled with insulating gas 18 is housed in 16b, and a classification gap 20 is built in ff1ii121).

The lightning arrester 16 is capable of providing sufficient overvoltage protection between the DC side gland of the converter transformer of the upper bridge and the ground.

The lightning arrester configured as described above operates as a conventional lightning arrester for the upper bridge because all the nonlinear resistance elements 16a are connected.

On the other hand, the lightning arrester for the lower bridge performs the following spherical operation. If an abnormal voltage occurs between the DC side winding of the converter transformer in the lower bridge and the ground, the separation gap 20 connected to the lightning arrester in FIG. 2 will be discharged, and the nonlinear resistance element 16a will be connected to the circuit. Become. The reason why the gap 2o discharges is because the capacitance between the gap 20 is small and the insulation resistance is large compared to the non-linear resistor connected in series with the gap 20, and most of the abnormal voltage occurs between the gear 2o. This is to create partial pressure. When the separation gap 20 is discharged, an abnormal voltage is applied to the non-linear resistance element 16a, which operates the non-linear resistance element 16a and removes the overvoltage. In other words, the insulation between the DC side winding of the converter transformer of the lower bridge and the ground is protected. At this time, the nonlinear resistance element 16a connected to the upper bridge side does not operate because the number of elements is greater than that on the ground side.

In other words, approximately the lower half of the nonlinear resistance element 16a operates, and the upper half does not operate.

As explained above, according to the present invention, the number of ground-to-ground lightning arresters inserted between the DC side winding of a converter transformer and the ground can be reduced by half. For example, in the case of 12-phase rectification, six wires can be reduced to three. This directly leads to downsizing of the converter station and cost reduction.In the above embodiment, the upper,
Although a two-stage bridge configuration on the lower stage (high pressure side, low pressure side) has been described, a converter station with more than one stage can also have a similar configuration and obtain the same effect.

Further, although an example of a gas-insulated conduit busbar constructed by inserting a high-voltage conductor into a conduit filled with insulating gas has been described, it may be one in which insulating oil is filled instead of insulating gas.

[Brief explanation of the drawing]

FIG. 1 is a schematic combination diagram of the main parts showing one embodiment of the present invention, and FIG. A configuration diagram showing an example of the device,
FIG. 3 is a circuit diagram showing an example of an AC/DC conversion station to which the present invention is applied. 1... High voltage stage conversion transformer, 2... Low voltage stage conversion transformer, 3, 4... AC/DC converter, 6... DC line, 9
゜10... Ground-to-ground lightning arrester, 12a, 12b... Gas insulated conduit busbar, 13... Valve hole, 16... Lightning arrester, 16a... Non-linear resistance element, 16b... Tank, 20 ...separation gap. Applicant's agent Patent attorney Takehiko Suzue Figure 1] 6 Figure 2

Claims (1)

[Claims] In a lightning arrester inserted between the DC side winding and ground of a high-voltage stage conversion transformer and a low-voltage stage conversion transformer, an internal element formed by stacking multiple non-linear resistance elements is installed inside a tank. The high voltage side terminal of the internal element is connected to the DC side winding of the high voltage stage conversion transformer, and the high voltage side terminal of the internal element is connected to the DC side winding of the high voltage stage conversion transformer, and the high voltage side terminal of the internal element is connected to the DC side winding of the high voltage stage conversion transformer. A lightning arrester for an AC/DC converting station, characterized in that a DC side winding of the low voltage stage conversion transformer is connected to the non-linear resistance element.