JPS6334167Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an overhead power transmission line for ultra-high voltage, and particularly to an overhead power transmission line that can effectively prevent corona noise during rainy weather.

When ultra-high voltage is applied to ultra-high voltage power transmission lines during rainy weather, corona may occur and corona noise may occur.

Conventional methods to prevent this include increasing the outer diameter of the wire, increasing the number of conductors by making it a multi-conductor, and loosely twisting the outermost wires of the wire (for example, 18537), methods are known in which the surface of the outermost stranded wire of an electric wire is artificially corroded to form fine irregularities.

Among these, the above method aims to alleviate the electric field on the surface of the wire by increasing the number of elementary conductors, but it has the drawback of increasing the cross-sectional area and weight of the wire, resulting in poor economic efficiency.

Particularly loud corona noise occurs during rainy weather because large water droplets adhere to the surface of electric wires and form surface protrusions, where electric field concentration occurs. Proposed. In other words, by loosely twisting the outermost wires or corroding the surface of the outermost stranded wires to form fine irregularities, the amount of water droplets adhering can be reduced by causing water droplets to fall early before they grow large. The aim is to reduce the number of coronavirus outbreaks.

However, in this case, since the outermost layer wire and the inner layer twisted wire are composed of ordinary aluminum conductors, from a microscopic perspective, the water droplets adhering to the surface of each wire are still large, and the corona is that large. No reduction effect could be expected. On the other hand, since the entire wire surface is slightly uneven, water droplets adhere smoothly to the wire surface and have excellent water wettability, but the wires are tightly twisted together. As a result, large water droplets were also formed, which was not necessarily sufficient.

On the other hand, in relation to human hearing, corona noise is particularly problematic because it is noise that continues for a long time after the rain has stopped, rather than noise during rain.
From this point of view, an overhead power transmission line that achieves effective corona reduction is required to have characteristics that allow corona noise to disappear immediately after the rain has stopped, that is, good drainage performance. However, in the conventional overhead power transmission lines including the above-mentioned existing proposals, it cannot be said that sufficient consideration has been given to this point.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, to provide an overhead power transmission line that can more effectively reduce corona noise and quickly eliminate corona noise after the rain has stopped. .

In other words, the gist of the present invention is to twist the outermost layer wires whose surfaces are artificially corroded to form micro-irregularities so that they are spaced apart, and where the distance between them is d and the wire diameter is D, 0.1<d. /D<1.0.

Embodiments of the present invention will be specifically described below with reference to the drawings.

Fig. 1 is a cross-sectional view of the overhead power transmission line of the present invention, in which the core wire is a steel wire 3 that shares the tension, an aluminum conductor 1 for current is attached to the outer periphery of the core wire, and the aluminum conductor 1 for carrying electricity is placed on the outer periphery of the core wire, and the aluminum conductor 1 is twisted in a spaced manner in the outermost layer. It is composed of a corona prevention wire 2.

The corona prevention wire 2 can be composed of an aluminum wire or an aluminum steel-covered wire (AS wire), and its surface is artificially corroded with an alkaline solution or an acid solution to form fine irregularities.

In this case, it is preferable from the viewpoint of manufacturing that the surface of the corona prevention wire 2 is subjected to a corrosion treatment before being twisted onto the aluminum conductor 1 in the state of a strand.

The corona prevention wire 2 thus formed is twisted on the aluminum conductor 1 with a spacing d to form the outermost layer, and when the diameter of the wire is D,
They are arranged so that 0.1<d/D<1.0, and have an overall sparse outer circumferential configuration.

Next, the corona noise prevention effect of this overhead power transmission line will be explained below.

Water droplets during rainy weather adhere to the inner layer aluminum conductor 1 and the outermost layer corona prevention wire 2, but the aluminum conductor 1
In the part shown in FIG. 2, the electric field is relaxed by the shielding effect of the corona prevention wire 2, so corona is extremely unlikely to occur. On the other hand, in the corona prevention line 2, the surface is artificially corroded to form fine irregularities, so the water wettability of the surface is extremely good, and water droplets adhere smoothly to the surface before becoming large particles. This makes a significant contribution to reducing the amount of corona.

Furthermore, not only that, Corona Prevention Line 2,
In the distance d and wire diameter D, 0.1<d/D<1.0
By doing so, the corona noise can be effectively eliminated quickly after the rain has stopped.

It is not clear why it is effective when d/D is in this range, but when d/D is 0.1 or less (closely twisted), water will not get wet over the entire surface of the transmission line. However, since the corona prevention wires 2 are placed very close to each other, rainwater is trapped between the wires, resulting in poor drainage and water droplets continuing to fall for a long time. On the other hand, if it is 1.0 or more (more sparsely twisted), the spacing between the strands of the corona prevention wire 2 will become too wide, and the exposed area of the inner layer aluminum conductor 1 will become large, resulting in water drainage. This is thought to be because the characteristics of the ACSR transmission line become closer to those of normal ACSR transmission lines and deteriorate.

With conventional overhead power transmission lines, including regular ACSR transmission lines, water droplets continue to fall from the wires for a long time even after the rain has stopped due to their poor drainage, and during this time the corona continues for a long time, but with the power transmission line of this invention Corona can disappear in time.

In Figure 3, d/D is 0.5, 0.08 and 1.2, respectively.
This figure shows the results of corona sound measurements in the case of 2. The corona noise was at a high level during water injection, but in the overhead power transmission line with d/D = 0.5, which is the subject of this invention, it rapidly increased after water injection was stopped. You can see how it drops to the background noise level. Moreover, FIG. 2 shows the corona sound measurement results 3 minutes after water injection was stopped, and it can be seen that in the range of 0.1<d/D<1.0, the corona is effectively extinguished early.

In addition, although the above-mentioned example is an example in which all the wire diameters are the same diameter, even if the strand diameter of the corona prevention wire is particularly small in order to keep d/D within the range of the present invention. good.

Furthermore, as a surface treatment method for the corona prevention wire, mechanical treatment such as sandblasting can also be used.

As explained above, when the overhead power transmission line of the present invention is used, the following advantages are obtained.

(1) The outermost wire surface is artificially corroded to form fine irregularities, so the surface has good water wettability and water droplets fall off quickly. In addition, since each strand is twisted in a spaced state under predetermined conditions,
Large water droplets are not formed before falling. Therefore, the water drainage properties of the power transmission line as a whole are significantly improved, and corona noise can be effectively reduced.

(2) Because it drains water extremely well, corona does not persist for long periods of time even after the rain has stopped, and can be eliminated in a short period of time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of an overhead power transmission line according to the present invention, and FIGS. 2 and 3 are diagrams showing the relationship between corona noise and d/D. 1... Aluminum wire, 2... Corona prevention wire (outermost layer wire), 3... Steel wire.

Claims (1)

[Scope of Claim for Utility Model Registration] When outermost layer wires whose surfaces are artificially corroded to form fine irregularities are twisted in a spaced state, where the distance is d and the diameter of the wires is D, 0.1 An overhead power transmission line configured so that <d/D<1.0.