JPS5949770B2 - How to prevent wind noise from multi-conductor power transmission lines - Google Patents

Description

[Detailed description of the invention] The present invention is particularly effective in semiconductor power transmission lines.

This invention relates to a method for preventing wind noise. In recent years, attention has been paid to the noise generated when overhead power transmission lines are subjected to wind pressure. This is because power transmission lines have the same cross-sectional shape in the longitudinal direction, so when wind blows on them, The air fluid flowing on the surface exhibits the same separation behavior in the longitudinal direction, and the resulting air vibration becomes regular in frequency, causing a peak in the sound output level in the frequency range of about 100 to 200 Hz, producing low-frequency noise. It is. In order to prevent this, it has been proposed to wind the strands 2 in a spiral around the outer periphery of the electric wire 1 as shown in FIG. 1, and its effectiveness has been proven.

In the case of the electric wire 1 made of a single conductor, the wire 2 may be wound in any direction, but as shown in Fig. 2, the electric wires 1 and 1' (not limited to two conductors) may be wound in parallel Each wire 1, 1' is arranged with a spacer (not shown)
In the case of semiconductor power transmission lines held at regular intervals by It turned out that there was.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a noise prevention method for electric wires that can most effectively prevent wind noise in semiconductor power transmission lines.

This will be explained below based on examples.

FIG. 4 is a diagram showing the results of a wind tunnel experiment conducted on a 240-ACSR (steel-core aluminum stranded) two-conductor power transmission line without any wind noise prevention treatment.

As seen in the figure, there are differences in the wind sound output level depending on the wind speed, but when the wind speed is 15 m/s, the wind sound output level is around 120 H2 (nearly 120 H2), and when the wind speed is 20 m/S, the wind sound output level is around 180 H2. It will be seen that level peaks P and P' are formed, and a pronounced noise is formed in a specific sound range.In the case of such a semiconductor power line, each electric wire 1, 1
It is possible to reduce the noise by winding wires around the wires, but if the wires 1 and 1' are placed parallel to the direction of the wind (indicated by arrows in Figures 2 and 3), In this case, the winding conditions of this strand make a clear difference in the noise reduction effect.

That is, FIG. 2 shows the strands 3 wound around adjacent electric wires 1, 1.
, 3 are all wound in the same direction, that is, in the same S direction in the figure, and in FIG. Line 3' is an explanatory plan view showing a case where the wires are wound in opposite directions in the Z direction. There is a clear difference in the noise prevention effect between the case of FIG. 2 and the case of FIG. 3 even though the wire diameter and the structure of the strands are the same. Figures 5 and 6 are diagrams showing the results of wind tunnel experiments regarding them.

The test wire was the same 240mILA used in the experiment shown in Figure 4.
A CSR2 conductor was wound with preformed wires having a wire diameter of 4 mm and a pitch of 250 mm in the S direction and the Z direction under the conditions shown in FIGS. 2 and 3, respectively. In Nos. 5 and 6, what is indicated as S-S is the case where adjacent electric wires 1 and 1'' are both wound in the same S direction as shown in Fig. 2, and indicated as S-Z. As shown in FIG. 3, adjacent electric wires 1 and 1'' are wound in opposite directions, one in the S direction and the other in the Z direction. Figure 5 shows the results of a wind tunnel experiment at a wind speed of 20 m/s.

In the case of S-S, the untreated heater P'' in Fig. 4 is approximately 7
The noise level decreased from 5 dB to about 68 dB, and although the noise reduction effect can be seen to some extent, in the case of S-Z, this decreased to 58 dB, and the wind noise level decreased by 10 dB all at once. The difference is obvious at first glance.
We don't know much about the cause of this, other than the results of wind tunnel experiments. I think this is because the different external shapes of adjacent wires increase the disturbance effect of the air and fluid, further hindering the periodization of the frequency J. In other words, the direction of the wind blowing in the direction of the arrow in Fig. 3 is disturbed by the strands 3 wound in the S direction of the electric wire 1, but in the next electric wire 1'', the direction of the fluid is disturbed by the strands 3'' wound in the Z direction. The fluid is now disturbed in the opposite direction, and it is thought that the degree of disturbance of the air fluid will be significant.If the disturbance of the air fluid is severe, the periodicization of air vibration will be further hindered. Figure 6 shows the results of a wind tunnel experiment at a wind speed of 15 m/s, and it can be seen that the behavior is similar to that at 20 m/s.

Similar experiments were repeated with different wire diameters and strand diameters, but it became clear that the results remained the same. As described above, according to the method according to the present invention, wind noise from multi-conductor power transmission lines can be more significantly reduced. The significance of this sleep is enormous.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a low-noise electric wire, Figures 2 and 3 are explanatory plan views showing the winding direction of a wire wound around a double conductor, and Figures 4 to 6
The figure is a diagram showing the results of wind tunnel experiments. 1, ]″: electric wire, 2, 3, 3″: bare wire.

Claims (1)

[Claims] 1. In a semiconductor power transmission line consisting of multiple electric wires arranged in parallel, spiral strands are placed around the outer periphery of each wire so that the winding direction of the strands is opposite between adjacent wires in the direction in which the wind blows. A method for preventing wind noise from winding semiconductor power lines.