JPS63274319A - Overhead power transmission line - Google Patents

Abstract

PURPOSE:To prevent galloping by bringing the wire twist cycle of an overhead power transmission line, to which a torsion preventive appliance is mounted, to one half or less of the cycle of vertical vibrations. CONSTITUTION:When an overhead power transmission line 1 receives wind, the vibrations of low frequency and large amplitude, galloping vibrations, are generated, and the cycle of twist of the power transmission line and the cycle of vertical vibrations coincide with each other at all times in this case. Consequently, the cycle of twist and the vertical cycle conform, and lift is received from wind, thus largely developing galloping vibrations. As a result, the wire twist cycle and the vertical cycle are made to differ, and a torsion preventive appliance 4 is constituted so that the twist cycle is brought particularly to one half or less of the vertical cycle, thus completely preventing the generation of galloping. Since the loop number of vibrations generated in the overhead power transmission line 1 between steel towers 2, 3 is made the same as the number of the torsion preventive appliances 4 set up to the overhead power transmission line 1 in most cases, the loop number of vibrations between the span can be determined by the number of the torsion preventive appliances fitted to the line 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overhead power transmission line that prevents snow accretion and gear roping in an overhead transmission TM.

[Prior art] When snow adheres to an overhead power transmission line, it slides around the circumference of the wire, rotates, and lands on the lower surface of the wire, and as this snow accretion and rotation occurs many times, the snow gradually becomes uneven in thickness. If this snow builds up into a large cylindrical shape, the heavy weight could cause the transmission line to break or the support tower to collapse.To prevent this, the twisted weight was suspended. Preventers are installed on power lines to prevent them from twisting @ to prevent snow from forming into giant cylinders.
When this snow-covered power transmission line is exposed to wind, it vibrates and causes so-called gear lopping, which fatigues the wire, so it is necessary to prevent this gear lopping from occurring.

For this reason, the applicant first proposed a method to reduce gear roping and prevent snow accretion by preventing the twisting period of the wire from being equal to the up-and-down period in an overhead power transmission line equipped with a twist preventer. He filed an application for an invention in which the twisting period was greater than the up-and-down period.

[Problems to be solved by the invention] Although the above-mentioned invention can be effective to some extent, the results of various subsequent experiments show that it is only a matter of simply making the twisting period and the vertical period different. It turned out that although gear ropping can be suppressed to some extent, it cannot be completely prevented.

Therefore, the present invention provides a technology that can completely prevent the occurrence of gear lopping on overhead power transmission lines and also prevent snow accumulation.

[Means for Solving the Torsion Point] In order to solve the above-mentioned problems, the present invention provides an overhead power transmission line equipped with a torsion preventer from which a weight hangs. The electric wire twisting period T'R is set so that TR<0.5 TV with respect to the vertical period TV.

[Function] As mentioned above, the wire twisting period TR is set to 0.5 of the vertical period TV.
By making it smaller than twice as much, torsional vibrations that match vertical vibrations are less likely to occur, and as a result, gear lopping will not occur, and since the anti-twist device is installed, large amounts of snow will not accumulate.

[Examples] Examples of the present invention will be described below with reference to the drawings. In Figure 1, 1 is an overhead power transmission line, 2 and 3 are steel towers, 4a, 4b
, 4c is a twist preventer attached to this power transmission line, and this twist preventer has a weight 7 provided at both ends of a rod 6 fixed to the clamp 5 as shown in the second figure. Attach to power transmission lines to prevent twisting of the transmission lines.

When this overhead power transmission line is exposed to wind, low-frequency, large-amplitude vibrations, or gearropping vibrations occur, and the frequency at which the transmission line twists and the frequency at which it vibrates up and down always match. When the rotating period and the vertical period match and receive lift from the wind, gear roping vibration develops significantly.

The twisting period and the up-and-down period are as follows: TR is the twisting period that occurs on the overhead power transmission line, and TV is the up-and-down period that occurs on the overhead power transmission line.
Then, the twisting period] ゛R is, and the vertical period ′I''V
It is. However, Id: Moment of inertia of the twist preventer (-・d) IC = Moment of inertia of the overhead power transmission line (kg-rrr) d: Restoration moment of the twist preventer (kg-nF/rad) C: Spring constant of the wire (kg-m/rad) g: Gravitational acceleration (m/Sec) S: Span length (m) n: Number of loops of vibration occurring in overhead power transmission lines W: Weight per unit length of electric wire (kg/m) 1゛: Tension (bet) added to overhead power transmission lines.

As mentioned above, the development of gearropping vibration is caused by the coincidence of the twisting period and the vertical period. Therefore, in the present invention, the wire twisting period 1'R and the vertical period 1゛v are made different, especially when Tll < 0.5 TV, and the twist preventer 4 is configured to satisfy this condition, thereby completely preventing the occurrence of gear lopping.

By the way, the twisting period] ゛R and the vertical period TV are determined by the conditions determined by the overhead power transmission line and the conditions determined by the twist preventer attached to it, but the spring constant of the electric wire, which is a condition already determined by the overhead power transmission line. Kc, the span length S, the unit length weight W of the electric wire, the tension T of the overhead power transmission line, and the moment of inertia Ic of the overhead power transmission line are known,
Since the gravitational acceleration g is also known, in order to set the wire twisting period 1゛R to be less than 0.5 times the vertical period TV as described above, the condition 1d of the twist preventer in the above-mentioned formula 0 is set.
, Kd may be appropriately selected.

That is, the moment of inertia Id of the twist preventer and the restoring moment d can be determined by selecting the weight of the weight 7 of the twist preventer 4 and the distance from its center of gravity to the center of the power transmission line.

In addition, the number n of vibration loops occurring in the overhead power transmission line between the steel towers 2 and 3 is almost always the same as the number of twist preventers 4 installed on the overhead power transmission line. For example, when one twist preventer is installed, One loose vibration occurs with this torsion preventer as the antinode of the vibration, and if N torsion preventers are installed, N loops of vibration will occur, so the number of vibration loops in this span is n. It can be determined by the number of anti-twist devices installed there.

For example, the overhead power transmission line is AC3R160tsa, the spring constant Kc is 0.35m, n+/rad, the single-position JIW is 0.7328kg/m, the span length S is 200m, the erection tension 1 is 1500 kg, and the steel towers 2 on both sides are .3
The distance between each arm and the nearest twist preventer 4a, 4c is 33 m, and each twist preventer 4a between them is 33 m.
, 4b, 4c with a spacing of 67 m and three twist preventers are installed, the number of vibration loops n occurring in the overhead power transmission line is 3.
In this case, the vertical period 'rv is given by the above equation 0.

Therefore, the wire twisting period Tll, that is, the TR value of the above formula 0 is TR<0.
5TV That is, the moment of inertia Id of the twist preventer and the restoring moment Kd of the twist preventer are set so that they are smaller than 0.5x O, 94 = 0.47 SEC, and the weight of the twist preventer 4 is set accordingly. What is necessary is to set the weight of the weight 7 and the distance from its center of gravity to the center position of the power transmission line.

In addition, instead of having the twist preventer configured as shown in the second diagram,
It can be modified into an appropriate configuration that can prevent vibrations of the overhead power transmission line, and the number of twist preventers installed on the overhead power transmission line can be adjusted to an appropriate number depending on the situation. be.

The present invention prevents the occurrence of gearropping in this way, and if the wire twisting period '1'R is set to be 0.5 or less of the vertical period TV, the vibration amplitude of the overhead power transmission line can be significantly reduced. As shown in the third diagram, the size becomes smaller.

The vertical axis A in the figure represents the vibration amplitude of the overhead power transmission line, the tower axis represents the ratio of the wire twisting period '1' R and the vertical period TV, and the curve B represents the vibration amplitude at various ratios of TR/TV. shows the value of As shown in curve B, in the region ■ above the dotted line where TR is greater than 0.5'I''V, the vibration amplitude A increases rapidly, but in the region ■ below the dotted line where TR<0.5 TV, the vibration amplitude increases. A is extremely small, and while this area ■ is a vibration area, the fill area ■ can be said to be an anti-vibration area, and thus TR/TV is selected as an anti-vibration area I, which is smaller than 0.5. By doing so, gearloping is prevented.

[Effects of the Invention] As mentioned above, the present invention provides a method for adjusting the wire twisting period 'I' R of an overhead power transmission line equipped with a twist preventer with respect to the vertical period 'rv.
By setting TR<0.5 TV, it is possible to prevent the occurrence of gear lopping, and by installing a twist preventer on the overhead power transmission line, it is also possible to prevent large amounts of snow from accumulating. It is.

[Brief explanation of drawings]

FIG. 1 is a drawing showing an overhead power transmission line according to an embodiment of the present invention;
Figure 2 is a diagram showing the twist preventer, Figure 3 is the wire twisting cycle]
It is a curve diagram showing the relationship between the ratio of the upper and lower periods of 'R1'rv and the vibration amplitude of the overhead power transmission line. 1: Overhead transmission line 4: Anti-twist device 5; 1! Line installation part 7: M weight patent applicant: Tohoku Electric Power Co., Ltd. Haka 1 person

Claims (1)

[Scope of Claims] In an overhead power transmission line equipped with a twist preventer in which a weight hangs from a wire attachment part, the wire twisting period TR that occurs in the overhead power transmission line is set such that TR<0.5 TV with respect to the vertical period TV. An overhead power transmission line characterized by: