JPH0755020B2 - Overhead power transmission line - Google Patents

Description

TECHNICAL FIELD The present invention relates to an overhead power transmission line for preventing snow accretion and galloping of the overhead power transmission line.

[Prior Art] When snow adheres to an overhead power transmission line, it rotates while sliding around the circumference of the wire and snows on the bottom surface of the wire. When such snowing and rotation are repeated many times, the snow accretion gradually becomes uneven. If the snow is developed into a large tubular shape as it develops, the heavy weight may cause breakage of the transmission line or accidental collapse of the support tower.To prevent this, the twist of the weight is suspended. A preventive device is attached to the transmission line to prevent the transmission line from twisting and prevent snow accretion from developing into a huge cylinder.
This snow-covered power transmission line vibrates when subjected to wind and causes so-called galloping, which causes the electric wires to fatigue, so it is necessary to prevent this galloping from occurring.

For this reason, a damper for preventing galloping of 3 loops or less, which is particularly susceptible to galloping damage, is used. This damper has a configuration in which an electric wire gripping portion is provided between an upper shaft portion and a lower shaft portion of a straight shaft, A weight is attached to the tip and the tip of the lower shaft, the center of gravity is located below the wire gripping part, and the twisting rotation frequency of the wire is a non-integer multiple of less than 3 times the fundamental frequency of vertical vibration. Then, by mounting this damper at asymmetric positions in the radial direction with respect to the electric wire on which the snow-difficulty ring is mounted at regular intervals, only three or less loops of various loop galloping are prevented. There is known a method for preventing wire twisting / rotation and galloping of a snow-difficulty electric wire disclosed in JP-A-51-149595.

[Problems to be Solved by the Invention] In the method for preventing wire twisting rotation and galloping of a snow-adhesive wire of the above-mentioned patent application, the basic frequency of the twisting frequency and the vertical frequency of the galloping wire of 3 loops or less are Even if the dampers are attached to the asymmetrical positions of the spanned wires, the twisting rotation frequency of the wires is set to a non-integer multiple of less than 3 times the fundamental frequency of the vertical vibration. However, there is a problem in that, even if the galloping can be suppressed to a certain extent and the vibration region II shown in FIG.

An object of the present invention is to solve the above-mentioned problems and to provide an overhead power transmission line capable of completely preventing all galloping of various loop numbers in spans and preventing snowfall. To do.

[Means for Solving Problems] In order to solve the above problems, the overhead power transmission line of the present invention is
In an overhead power transmission line equipped with an anti-twist device in which a weight hangs down from the wire attachment part, use the same number of anti-twist devices as the upper and lower vibration loops of the wire in the span, and use the anti-twist device at each antinode position of each vertical vibration loop. Each of them is equipped with the above-mentioned twist preventive device so that the electric wire twisting cycle TR generated in the overhead power transmission line becomes TR <0.5TV with respect to the vertical vibration cycle TV.

[Operation] Using the same number n of twist-preventing loops as the number of vertical vibration loops of the electric wire in the span, by attaching the twist-preventing devices to the antinodes of each of the n vertical vibration loops, It is possible to prevent not only galloping of the number of loops of 3 or less as in the method of preventing wire twist rotation and galloping of the snow adhering wire, but also all galloping of various loop numbers in the span.

Further, by making the wire twisting cycle TR of the n vertical vibration loops in the span smaller than 0.5 times the vertical vibration cycle TV, the wire twisting rotation prevention and galloping prevention method of the above-mentioned conventional snow adhering wire is prevented. Remarkably, twisting vibrations that match the vertical vibrations of all loop numbers do not occur, and all galloping of various loop numbers can be completely prevented.

In addition, since the twist preventive device is attached to the electric wire, a large amount of snow does not occur.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an overhead power transmission line, 2 and 3 are steel towers, 4a, 4b, 4c are twist preventive devices attached to the power transmission line, and the twist preventive device is a clamp 5 as shown in FIG. Weights 7 are provided at both ends of the rod 6 fixed to the. The clamp 5 is attached to the power transmission line to prevent the transmission line from being twisted.

When the overhead power transmission line 1 receives wind, low-frequency, large-amplitude galloping vibration occurs in the span, but the period in which the galloping vibration wire twists and the period in which it vertically vibrates always match. In this way, the twisting cycle and the vertical vibration cycle coincide with each other, and the lift force from the wind causes the galloping vibration to greatly develop.

The twisting cycle and the vertical vibration cycle are: TR is the electric wire twisting cycle that occurs in the overhead power transmission line, and TV is the vertical vibration cycle that occurs in the overhead power transmission line. And the vertical oscillation period TV is Is. However Id: twisting preventer moment of inertia (kg · m ²⁾ Ic: moment of inertia of the overhead power transmission line (kg · m ²⁾ Kd: twisting preventer of restoring moment (kg · m / rad) Kc : spring constant of the wire (Kg ・ m / rad) g: Gravitational acceleration (m / sec) S: Span length (m) n: Number of vibration loops in the overhead transmission line W: Weight per unit length of wire (kg / m) T : Tension (kg) applied to the overhead power transmission line.

As described above, the development of galloping vibration is due to the coincidence between the twist cycle and the vertical vibration cycle. Therefore, in the present invention, the electric wire twisting period TR and the vertical vibration period TV are made different from each other, and in particular, TR <0.5TV is set, and the twist preventive device 4 is configured to satisfy this condition.

The twisting period TR and the vertical vibration period TV are determined by the conditions determined by the overhead power transmission line and the conditions determined by the twist preventive attached to the overhead power transmission line.The spring constant Kc of the wire, which is the condition already determined by the overhead power transmission line, 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, and the gravitational acceleration g is also known. Can be set to be 0.5 times or less of the vertical vibration period TV, the conditions Id and Kd of the anti-twist device in the above equation can be appropriately selected. That is, the moment of inertia Id and the restoring moment Kd of the anti-twist device can be determined by selecting the weight of the weight 7 of the anti-twist device 4 and the distance from the center of gravity position to the center position of the power transmission line.

The number of upper and lower vibration loops of the galloping vibration of the electric wire 1 occurring in the span between the steel towers 2 and 3 varies depending on the situation.
Assuming that the number is n, the same number n of twisting preventive devices as the number of vertical vibrating loops are used for the electric wire 1 within the span, and each twist preventive device is connected to the antinodes of the n upward and downward vibrating loops of galloping vibration. Attach to each position.

For example, an overhead power transmission line has an ACSR of 160 mm and a spring constant Kc of 0.35 k.
g · m / rad, unit length weight W is 0.7328 kg / m, span length S is 200
m, the erection tension T is 1500 kg, and if five twist prevention devices are attached, the number of loops n of vibration generated in the overhead power transmission line becomes 5, and at this time, the vertical vibration period TV is calculated by the above equation. Becomes

Therefore, the wire twist cycle TR, that is, the above equation The inertia moment Id of the anti-twist device and the restoring moment Kd of the anti-twist device are set so that the TR value of is smaller than TR <0.5TV, that is, 0.5 × 0.564 = 0.28sec for the vertical oscillation period TV value of 0.564sec. Set, so that the weight 7 of the anti-twist device 4
The weight and the distance from the center of gravity to the center of the transmission line may be set.

By setting the wire twisting cycle TR to be 0.5 times or less of the vertical vibration cycle TV as described above, the vibration amplitude of the wire between the spans is significantly reduced as shown in FIG. The vertical axis A in the figure is the vibration amplitude of the span wire, the horizontal axis is the ratio of the wire twist cycle TR to the vertical vibration cycle TV, and the curve B is the value of the vibration amplitude at various ratios of TR / TV. Show. In the region II above the dotted line where TR is greater than 0.5TV as shown by the curve B, the vibration amplitude A increases sharply, but in the region I below the dotted line where TR <0.5TV, the vibration amplitude A
Becomes extremely small. Region II is a vibration region, while region I is a vibration isolation region.

As mentioned above, by selecting TR / TV in the vibration isolation area I smaller than 0.5, the galloping vibration amplitude of the wire between spans becomes much smaller than before, and n twist preventive devices are used. By mounting the upper and lower vibration loops at the antinodes respectively, not only galloping of three or less loops as in the conventional case, but all galloping of various loop numbers in the span are prevented.

The twist preventive device can be modified into an appropriate structure capable of preventing the vibration of the overhead power transmission line, instead of the structure shown in FIG.

[Effects of the Invention] As described above, according to the present invention, as many twist preventives as the number of vertical vibration loops of a spanned electric wire are used to attach the anti-vibration loops to the antinodes of the vertical vibration loops, and the wire twisting cycle By setting TR to TR <0.5TV with respect to the vertical oscillation period TV, it is possible to prevent not only galloping with three or less loops as in the past, but also all galloping with various loops in the span. . In addition, a large amount of snow is prevented by installing a twist preventive device for the overhead power transmission line.

[Brief description of drawings]

FIG. 1 is a drawing showing an overhead power transmission line of one embodiment of the present invention,
Fig. 2 is a drawing showing the twist prevention device, and Fig. 3 is a wire twist cycle T.
FIG. 6 is a curve diagram showing the relationship between the ratio of R, the vertical vibration period TV, and the vibration amplitude of the overhead power transmission line. 1: Overhead transmission line 4: Anti-twist device 5: Wire mounting part 7: Weight

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Tachisaki 3-7-1, Ichibancho, Sendai City, Miyagi Prefecture Tohoku Electric Power Co., Inc. (72) Inventor Masanori Oishi 500 Kiyotaki Town, Nikko City, Tochigi Prefecture Furukawa Electric Co., Ltd. Inside the Nikko Denki Copper Works (72) Inventor Takao Iketani 500 Kiyotaki Town, Nikko City, Tochigi Prefecture Furukawa Electric Co., Ltd. Inside the Nikko Denki Copper Works (72) Inventor Koji Akasaka 500 Kiyotaki Town, Nikko City, Tochigi Prefecture Furukawa Electric Co., Ltd. Stock company Nikko Denki Copper Works (56) References JP-A-51-14959 (JP, A)

Claims (1)

[Claims] 1. In an overhead power transmission line equipped with a twist preventer in which a weight hangs down from an electric wire attachment portion, the same number of twist preventers as the number of vertical vibration loops are attached to the antinodes of the vertical vibration loops, respectively. An overhead transmission line characterized in that the electric wire twisting cycle TR that occurs in the transmission line is set to TR <0.5TV with respect to the vertical oscillation cycle TV.