JPH0543986B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] 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 is a method for simulating snow accretion on overhead power lines that rotate due to snow accumulation using wire samples that are much shorter than overhead power lines with long spans. It is related to.

[Conventional technology]

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

The accumulation of snow becomes the largest when it forms a snow pile around the electric wires, and one of the processes by which this snow pile develops is when wet snow adheres to the sides of the electric wires during strong winds, and the moment In one case, the electric wire rotates and snow accumulates on it and rotates repeatedly, causing it to develop into a pipe of snow.The other is that the electric wire generally slopes like a catenary near the support point (steel tower). When snow accretes on the side of this part, the accreted snow rotates downward along the twists of the outermost stranded wire layer of the wire, and then the snow accretes there and rotates repeatedly. It is thought that there may be cases where snow falls.

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

[Problem to be Solved by the Invention] In order to observe snow accretion conditions in a laboratory using the natural snowfall described above, electric wires were manually moved to simulate the rotation of the electric wires due to snow accretion on the sides of the power transmission lines described above. Attempts have been made to observe snow accretion by twisting the cable, but the actual span length of power transmission lines is several hundred meters long.
Even if snow is uniformly deposited on the span, the rotation angle differs depending on the position of the span, 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. Since it will be different, what is the situation of each part?
It was difficult to estimate.

[Means to solve the problem]

Although this invention is a simulation method, it is an improvement over the conventional method in which it is difficult to accurately grasp the actual situation as described above. This method provides a simulation method that can be used to grasp the above-mentioned overhead power transmission line by storing the relationship between torque and rotation angle at each position in the span in advance in a computer according to the span length of the overhead power transmission line. The torque generated by artificially depositing snow on a wire sample to be simulated is detected, and the rotation angle corresponding to the torque at a predetermined position of a predetermined span length, which is the same as this torque and stored in the computer, is applied to the wire sample, and the artificial snow is deposited on the wire sample. It is something that does snow.

[Effect]

When simulated snow is deposited on a simulated wire sample, the rotation angle given to the wire sample by the torque applied by the snow deposit is similar to that of an actual overhead power transmission line, which is uniformly deposited in the length direction. If it snows,
For example, it is much smaller than the rotation angle caused by the same torque as above in the center of the span, but in this invention, snow is deposited while always applying this actual rotation angle to the wire sample, so snow accretion The rotation of the generated wire sample 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〕

The simulation method of the present invention will be explained with reference to FIG. FIG. 1 shows an apparatus including a computer circuit for carrying out the method of the present invention, in which numeral 1 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 wire sample 1 in a freely rotatable manner; 3 and 4 are on the axis of the wire sample 1; 1 is a torque sensor and a pulse motor connected in sequence; 5 is a connector between the electric wire sample 1 and the torque sensor 3; and 6 is a connection between the torque sensor 3 and the pulse motor 4. 7 is CPU, 8
is the A/D converter, 9 is the I/O port, and CPU7
are connected to the torque sensor 3 via the A/D converter 8 and to the pulse motor 4 via the I/O port 9, respectively. 10 is the memory set in the CPU 7, which is shown in Figures 3 and 4 below.
It stores numerical values plotting the torque-rotation angle curve at a certain position in the span of the overhead power transmission line actually installed in the figure.

FIG. 2 shows an example of the structure of the electric wire sample 1 used to carry out the method of the present invention.
2 is an aluminum pipe, and 22 is a twisted wire layer made of aluminum wires twisted around the outer periphery 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 that on a line where ACSR (steel core aluminum stranded wire) with a cross-sectional area of 240 mm ² is installed as an overhead power transmission line, the snow that adheres to the side of the power line is the same as the length of the power line between the spans. Figure 3 shows the torque-rotation angle curve at a certain position along the length of the transmission line, assuming that the snowfall intensity is also uniform along the length of the transmission line. If a certain position in the direction is the center position of each span length, then FIG. A case is shown in which the positions in the length direction are positions P ₁ , P ₂ , P ₃ and P ₄ for each span length. The horizontal axis is the torque applied to the power transmission line (g cm/m), and the vertical axis is the rotation angle (degrees) given to the power transmission line by the torque. Curve A in each figure is the span length S = 400 m, Curve B has a span length S = 300 m, curve C has a span length S = 250 m, and curve D has a span length S
= 200m.

Fig. 3 shows representative curves at the center position of each span, and Fig. 4 shows representative curves at positions P ₁ to _{P 4} , but this is done by equating the span length to an appropriate number. For example, it is preferable to equally divide into unit lengths and obtain a torque-rotation angle curve in advance for each position therein.

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 as snow accumulates thereon, causing the wire sample 1 to rotate around its axis. The moment at this time is measured by the torque sensor 3. The value is passed through the A/D converter
Sent to CPU7. 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, and the torque value from the torque sensor 3 is stored in advance.
When input to the CPU 7, the rotation angle for the torque at the position of the predetermined span length to be simulated is called, which is the same as the torque value, and this is
The pulses are transmitted to the pulse motor 4 through the O port 9, 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 1 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 1 is much shorter than the span length of the transmission line to be simulated, and for example, the electric wire sample 1 has the same snow accretion as the snow accretion at the center of the span. Even if the moment is applied, the electric wire sample 1 will only be given a rotation angle that is much smaller than the actual rotation angle, but the torque due to the moment is detected by the torque sensor 3 and stored in the memory 10 in advance. The CPU 7 calls 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 situation is the same as the rotation that occurs when the same amount of snow is 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, and the snow will gradually accumulate, and it will be difficult to see how it develops into pipe snow. It is possible to simulate fairly accurately in the laboratory, such as how the snow will fall and what conditions will occur before the accumulated snow will fall.

[Brief explanation of drawings]

Fig. 1 is a side view of a device including a computer circuit for explaining the snow accretion simulating method of the present invention;
The figure is a cross-sectional view showing an example of the structure of a wire sample simulating a power transmission line, and Figures 3 and 4 are torque-rotation angle curves at a certain position in the length direction of a power transmission line with various span lengths to be simulated. be. 1; Electric wire sample, 2; Support frame, 3; Torque sensor, 4; Pulse motor, 7; CPU, 8; A/
D converter, 9; I/O port, 10; memory, 1
1: Counterweight for preventing twisting, 21: Aluminum pipe, 22: Twisted aluminum wire layer, S: Span length, curves A, B, C, D: Torque-rotation angle at a certain position at various span lengths Curves, P ₁ to P ₄ ; torque-rotation angle measurement points.

Claims (1)

[Claims] 1 The relationship between the torque and rotation angle at each position in the span of the overhead power transmission line is stored in advance in a computer,
The torque generated by artificially depositing snow on a wire sample simulating the above-mentioned overhead power transmission line is detected, and the rotation angle corresponding to the torque at a predetermined position of a predetermined span length, which is the same as this torque and stored in the above-mentioned computer, is applied to the above-mentioned wire sample. A method for simulating snow accretion on an overhead power transmission line, characterized by performing artificial snow accretion while applying snow.