JPH02159594A - Simulating method of snow coating on overhead transmission line - Google Patents

Abstract

PURPOSE:To enable accurate simulation of the process of formation of a snow tube or drop of snow in simulated manner by a method wherein the state of snow coating on an overhead transmission line being rotated by the snow coating is simulated by using a short wire sample. CONSTITUTION:A wire sample 1 is much shorter than a span length of a transmission line to be simulated. Even when the same snow coating as at the central position of a span, for instance, is given to the sample 1, therefore, only a much smaller rotational angle than an actual one is given to the sample 1 by the moment alone given by said snow coating. However, a torque by the moment is detected by a torque sensor 3, a rotational angle to the same torque as the above at a prescribed position of a prescribed transmission line, which is stored beforehand in a memory 10, is accessed by CPU 7, the value thereof is used as the number of pulses, and a pulse motor 4 is rotated to said rotational angle. The wire sample rotated thereby is put in the same state of rotation as with the one caused when the same amount of snow with that sticking to the sample is given to the prescribed position of the prescribed actual transmission line.

Description

[Detailed Description of the Invention] [Industrial Field of Application] When snow adheres to the side of an overhead power transmission line, the electric wire rotates due to the moment, and further snow accumulates there.

This invention relates to a method for simulating snow accretion on overhead power lines that are rotated due to snow accumulation using a wire sample that is much shorter than an overhead power line with a long span. be.

[Prior Art] There are various forms of snow damage to overhead power transmission lines, and the most important one is snow accretion on electric lines due to wet snow under strong winds, and the main problems are the snow load and the gears of electric lines. Lopping vibration.

The accumulation of snow becomes the largest when it forms a snow pile around the electric wires, and the process of the snow pile developing is as follows:
One is when wet snow adheres to the side of an electric wire during strong winds, the moment causes the electric wire to rotate, and the snow buildup and rotation are repeated, causing it to develop into a pipe of snow. Generally, the cable is inclined like a catenary near the support point (steel tower), and if snow falls on the side of this part, the snow will rotate downward along the twists of the outermost wire layer of the wire. It is thought that there are cases where snow can form due to repeated movement, snow accretion, and rotational movement.

However, these phenomena occur infrequently, and it is extremely inefficient to wait for them to elucidate the phenomenon and research countermeasures. Therefore, we have developed a simulation method that uses natural snowfall to blow snow onto electrical wire samples. is being developed.

[Problems to be Solved by the Invention] In order to observe a laboratory comparative snowfall situation using the above-mentioned natural snowfall, a manual test was carried out to simulate the rotation of the power line caused by f-lightning to the side of the above-mentioned power transmission line. Attempts have been made to observe snow accumulation by twisting power lines, but the actual spans of power transmission lines are as long as several 100 lines, and even if the span is evenly covered with snow, The rotation angle differs depending on the position of the wire, and since the electric wire has a catenary, the relationship between torque and rotation angle is not linear. Therefore, with the above method, even if it is possible to capture the situation in a part of the span, it is difficult to know exactly which part of the span it is, and the snow situation in other parts is different from that. Therefore, it was difficult to estimate what the situation was in each part.

[Means for Solving the Problems] This invention improves the conventional method, which is difficult to accurately grasp the actual situation as described above, even though it is a simulation method.
This method provides a simulation method that can accurately determine the snow accretion situation at which position in the span of the line, and calculates the torque and rotation angle at each position in the span according to the span length of the overhead power transmission line. A computer stores in advance the relationship between Artificial snow deposition is performed while giving the electric wire sample a rotation angle relative to the torque at a predetermined position.

[Effect] When simulated snow is deposited on a simulated electric wire sample, the rotation angle given to the wire sample by the torque applied by the snow accretion is uniform in the length direction of the actual overhead power transmission line. When snow accretes, for example, in the center of the span, the rotation angle is considerably smaller than the rotation angle caused by the same torque as described above. However, in this invention, snow accretion is carried out while always applying this actual rotation angle to the wire sample. The rotation of the wire sample caused by snow is always given the rotation angle that would occur if the same snow had fallen at a predetermined position in a predetermined span length of an actual overhead power transmission line.

[Example] A simulation method of the present invention will be described with reference to FIG. FIG. 1 shows an apparatus including a computer circuit for carrying out the method of the present invention, where l is a simulating wire sample;
An example of its structure is shown in FIG. 2 and will be described later. 2 is a support frame that supports both ends of the electric wire sample l in a freely rotatable manner;
3 and 4 are on the axis of the wire sample 1, and 1
A torque sensor and a pulse motor are sequentially connected to the wire sample 1 on the opposite side of the wire sample 1 to the support frame 2, and 5 is the wire sample 1 and the torque sensor 32.
The connector 6 is a connecting body between the torque sensor 3 and the pulse motor 4. 7 is CPU, s is A/D converter, 9 is I1
The CPU 7 is connected to the torque sensor 3 via the A/D converter 8 and to the pulse motor 4 via the I10 port 9 through the I10 port. 10 is a memory set in the CPU 7, and this is a numerical value plotting the torque-rotation angle curve at a certain position in the span of the overhead power transmission line actually installed as shown in FIGS. 3 and 4, which will be described later. is memorized.

FIG. 2 shows an example of the structure of the electric wire sample 1 used to carry out the method of the present invention, in which 21 is an aluminum pipe, and 22 is a twisted wire layer made of aluminum wire twisted around the outer circumference of the pipe. Although it is most desirable that this is the same structure as the actual overhead power transmission line to be simulated, it is not necessary to do so, as long as the shape, material, outer diameter, etc. of at least the outermost layer are the same.

Figures 3 and 4 show an overhead power transmission line with a cross-sectional area of 240 mm.
Assume that on a railway line with AS' AC5R (steel core aluminum stranded wire) overhead lines, the lightning that attaches to the side of the transmission line is uniform along the length of the transmission line in the span, and the intensity of snowfall is also uniform. The torque-rotation angle curve at a certain position along the length of the transmission line when , 4th
The figure shows a power transmission line in which a counterweight 11 for preventing twisting is attached to each span length shown linearly in the upper left, and a certain position in the above length direction is a position P for each span length. The cases where t , P z , P s and P are shown. The horizontal axis is the torque applied to the transmission line (
The vertical axis is the rotation angle (degrees) given to the power transmission line by the torque, and the curve A in each figure is the span length S = 4.
00m, curve B is for the span length $-300m, curve C is for the span length S-250 layer, and the curve is for the span length S=200m.

Figure 3 representatively shows the curve at the center position of each span, and Figure 4 representatively shows the curves at positions P1 to P, which are calculated by dividing the span length into an appropriate number of equal parts. For example, it is preferable to equally divide the length into unit lengths and obtain a torque-rotation angle curve in advance for each position within the unit length.

In FIG. 2, snow is now applied to the sides of the wire sample 1 uniformly along its length. A moment is applied to the wire sample 1 according to the snow accumulation thereon, and the wire sample 1 rotates around its axis. The moment at this time is measured by the torque sensor 3. The value is sent to the CPU 7 through the A/D converter. A memory 10 containing plotted values of torque-rotation angle curves for various span lengths shown in FIGS. 3 and 4 is preset in the CPU 7.
When the torque value from the torque sensor 3 is input to the CPU 7, the rotation angle for the torque at the position of a predetermined span length to be simulated, which is the same as the torque value, is called, and this is transmitted through the I10 boat 9. Pulse motor 4
is transmitted in the form of pulses, and the pulse motor 4 is rotated to a rotation angle corresponding to the number of pulses. Along with the rotation, the torque sensor 3 and the electric wire sample l also rotate. In this way, electric wire sample 1 is given the same rotation angle that would occur if the same snow that had landed on it was at a predetermined position in a predetermined span length of the transmission line, and furthermore, The successive snowfall is as if the same situation as the snowfall situation at the predetermined position of the above-mentioned predetermined power transmission line has been created.

[Effect of the invention] According to the snow accretion simulating method of the present invention, the electric wire sample l is
A wire sample l that is much shorter than the span length of the transmission line to be simulated, and has the same snow accretion as snow accretion at the center of the span, for example.
However, the torque sensor 3 detects the torque due to the q moment and stores it in the memory 10 in advance. The CPU 7 calls up the rotation angle for the same torque as above at a predetermined position of a predetermined power transmission line, and uses that value as the number of pulses to rotate the pulse motor 4 to that rotation angle. The electric wire sample undergoes the same rotation that would occur if the same amount of snow as the amount of snow deposited thereon was applied to a predetermined position of an actual power transmission line.

Therefore, even if snow continues to accumulate on this line, the same rotational situation as the actual power transmission line will be obtained accordingly, and the snow will gradually accumulate, and how it will turn into pipe snow. It is possible to simulate quite accurately in the laboratory the conditions in which accumulated snow sometimes falls.

[Brief explanation of the drawing]

FIG. 1 is a side view of a device including a computer circuit for explaining the snow accretion simulating method of the present invention, FIG. The figure shows torque-rotation angle curves at certain positions along the length of power transmission lines with various span lengths to be simulated. 1; Electric wire sample, 2: Support frame, 3; Torque sensor,
4; pulse motor, 7; CPU, 8. A/D converter, 9
; I10 port, 10; Memory, 11; Counterweight for preventing twisting, 21; Aluminum pipe, 22; Twisted aluminum wire layer, S: Span length, curve A% B, C, D, at various span lengths Torque-rotation angle curve at a certain position, PI~P
, ; Torque-rotation angle measurement point.

Claims (1)

[Claims] The relationship between torque and rotation angle at each position in the span of an overhead power transmission line is stored in advance in a computer, and the torque generated by artificially depositing snow on a wire sample simulating the above-mentioned overhead power transmission line is detected. A method for simulating snow accretion on an overhead power transmission line, characterized in that artificial snow accretion is performed while giving the electric wire sample a rotation angle corresponding to the torque at a predetermined position of a predetermined span length stored in the computer.