JP2612066B2 - Transmission line road snow forecasting method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting snow accretion on a transmission line, and particularly to early determination of the quality of snow that is falling at that time, and thereby, to overload the transmission line. The present invention relates to a snowfall forecasting method in which it is determined whether or not snow is generated so that necessary measures can be taken in advance.

[Background Art] It is well known by annual reports and the like that if heavy snowfall occurs on a transmission line, there is a risk that the transmission line may be broken or, in the worst case, a tower may collapse.

However, heavy snowfall does not necessarily mean heavy snowfall. Depending on the snow quality, no matter how much heavy snow there is, the transmission line hardly accumulates, and the snow quality of the snow, such as the heavy snowfall, is limited. That is, dry snow having a low water content and a small specific gravity falls for a long time without stopping even if it adheres to the power transmission line, and does not progress to a large snowfall. However, when wet snow having a high water content and a large specific gravity adheres to the electric wire, a water film is formed between the surface of the electric wire and the snow-covered mass, and this water film prevents the snow from falling from the electric wire. In this way,
The snow falls on the electric wire without falling, starts rotating by its own weight, and develops into a large cylindrical snow state around the electric wire as it is, resulting in the heavy snowfall, which leads to disconnection or collapse of the steel tower.

In addition to the above-mentioned snowfall on electric wires, wet snow easily adheres to steel towers, and after it adheres, other snow damage problems such as freezing, falling into large snow chunks, and damaging structures below are also seen. Have been.

The occurrence of the above-mentioned wet snow greatly depends on the weather conditions, and there is no such wet snow under severe cold. Although it occurs in weather conditions where the outside air temperature is relatively warm above zero degrees Celsius and where the humid atmosphere is easy to blow into, such weather conditions are not always dangerous to the transmission line. Under such climatic conditions, it is a more special case that the wet snow forms the large snow covered snow. That is why major snow accidents on transmission lines are likely to concentrate in relatively limited areas.

Even if it is possible to predict the presence of snow from weather conditions, it is actually impossible to predict whether the snow is dangerous for the transmission line.

For this reason, proposals have been made to detect when a situation in which snowfall poses a danger to the power transmission line and to issue an alarm.

For example, there is a method of monitoring the tension of the electric wire and issuing an alarm when the tension exceeds a certain value, or a method of arranging a light emitting element and a light receiving element and optically detecting snowfall.

[Problem to be Solved by the Invention] In the method of warning the danger by monitoring the tension of the electric wire, an alarm is not issued unless the tension is increased to a certain level or more, and the alarm is issued. Sometimes the snow is already accumulating and it is too late to respond, and from the viewpoint of taking sufficient measures, little effect can be expected.

Further, in the case of the above-mentioned optical snowfall detection sensor, it is possible to judge whether it is snowfall or rainfall or to start snowfall, but it is not possible to judge whether snow quality is harmful to the transmission line.

In addition, there are sensors devised to be able to detect the temperature and also to detect the possibility of the wet snow,
When the outside temperature is higher than the freezing point, there are many malfunctions such as determining that snowfall is rain, and the reliability is low in practical use.

For this reason, at the moment, if it is likely to become wet snow due to weather conditions etc., we will place guards appropriately,
The fact is that they rely on human resources to watch out for emergency situations, and the locations of such human resources are limited, so they do not always function well and contain problems that are troublesome. That is the reality.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art, and to automatically determine whether or not snowfall is harmful to a power transmission line without manual operation, and to determine whether or not the site is a remote place. It is an object of the present invention to provide a new snowfall forecasting method in which the used equipment can be freely installed regardless of the above.

Means for Solving the Problems According to the present invention, a transmitting and receiving device for millimeter wave radio waves and a receiving device are arranged at a predetermined interval in or near a power transmission tower, and a radio wave transmitted from the transmitting device exists halfway. The difference in the amount of attenuation attenuated by the snow quality of the snow is received and sensed by a receiving device, and the result received by the receiving device is transmitted to a remote monitoring place using a communication means.

[Operation] There is a large difference in the amount of moisture contained between dry snow and wet snow, and the dielectric constant of wet snow containing a large amount of moisture contained in snow becomes very large. Therefore, if millimeter waves that are easily attenuated due to the presence of such a dielectric material are transmitted and received in a snowfall space, it is easy to determine from the extent of the attenuation whether dry snow or wet snow that can adversely affect the transmission line. be able to.

[Example] Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is an explanatory diagram showing a concrete example of a snow accretion forecasting apparatus according to the present invention in which a transmitter 1 and a receiver 3 are installed on main legs 10a, 10a, which are tower members.

A millimeter wave or a quasi-millimeter wave is transmitted from the transmitter 1 via the transmission antenna 2 and received by the receiver 3 via the reception antenna 4.

If there is no snowfall, there will be almost no attenuation of radio waves in the transmission and reception.

If there is snowfall, radio waves are attenuated by the presence of snow because it is a dielectric. As described above, the amount of attenuation of a radio wave due to a dielectric substance existing in the middle is greater as the frequency of the radio wave is higher. Therefore, in the present invention, millimeter waves having the highest frequency are used as radio waves for transmission and reception, and the sensitivity of attenuation is made as large as possible.

In this case, if snow has occurred on the antenna 2 or 4,
The influence on the transmission / reception sensitivity itself increases, and correct detection cannot be performed. In the present invention, as a preferred embodiment, as shown in FIG. 2, a heating element 5 is built in the antenna 2 or 4 to prevent the antenna from snowing.

However, as shown in FIG. 3, if the snow cover 30 is provided above the antenna 2 or 4 to prevent the snow 30 from directly falling on the antenna, it is not necessary to incorporate the heating element 5 therein.

If there is snowfall in the space between the transmitter 1 and the receiver 3 configured as described above and during which millimeter waves are transmitted and received,
The received wave is attenuated as compared with the case where there is no snowfall.
The amount of attenuation changes depending on the magnitude of the dielectric constant of snow in that case.

Water is a substance having a large dielectric constant (dielectric constant at 0 ° C. is about 88—a scientific chronological table). Dry snow with a low water content has a low dielectric constant due to low water content. On the other hand, wet snow containing a large amount of water in which the ice of snowflakes has melted has a very large dielectric constant. In addition, it is observed that the amount of attenuation of radio waves due to wet snow is even greater than the amount of attenuation due to rain, and it is 2 to 14 times that of normal temperature rain, due to the slow falling speed of snow. Therefore, there is a marked difference in the attenuation of radio waves depending on whether the snow falling in the space between the transmitter and the receiver is dry snow or wet snow.

If the degree of attenuation due to the electrical properties is determined in advance by an experiment, it is possible to accurately and early determine the snow quality of the snow that is starting to fall at that time only by detecting the amount of attenuation.

If the snow quality of the snow that started falling early is known, it can be determined early whether the transmission line will be adversely affected.
As a result, it is possible to take immediate measures and minimize snow damage.

The change in the amount of attenuation detected by the receiver 3 is provided in various places, for example, through a public line if there is a public line, or by using a radio signal when there is no public line. It is sufficient to notify a management department such as a construction office.

On the other hand, in recent years, the optical file combined overhead ground line (hereinafter referred to as OPGW) has been extended over a wide area on major trunk lines.

FIG. 4 is an explanatory diagram showing an embodiment in which the above-mentioned notification is made using the OPGW 11.

The underline 11a is pulled down from the OPGW 11 along the steel tower 10, and this is connected to the receiver 3 via the repeater 12, and the result received by the receiver 3 is transmitted via the OPGW 11 and the alarm device of the construction office 20 is transmitted. The configuration is such that an alarm can be issued by 21. With this configuration, without preparing a special transmission path,
This device can be easily installed.

According to the above embodiment, since the equipment required for snow forecasting is installed in the steel tower, there is no need to secure a special land,
There is a special advantage in that the output of the radio wave may be weak, so there is no possibility of interference with the neighborhood. However, it does not necessarily have to be installed inside a steel tower,
There is no harm in selecting an appropriate place as needed.

[Effects of the Invention] As described above, according to the present invention, it is possible to automatically and automatically determine harmful snow on a power transmission line at an early stage, and it is possible to quickly implement a countermeasure against snow damage at an early stage. And prevent serious accidents such as the collapse of steel towers,
Snow damage on the transmission line can be minimized.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the method according to the present invention.
FIG. 3 is a cross-sectional view showing an embodiment of the configuration of the antenna, and FIG.
FIG. 4 is an explanatory view showing an example in which a snow cover is provided, and FIG.
FIG. 3 is an explanatory diagram showing a transmission system using OPGW. 1: Transmitter, 3: Receiver, 2,4: Antenna, 5: Heating element, 6: Snow cover, 10: Tower, 10a: Tower main leg, 11: OPGW.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-190094 (JP, A) JP-A-50-62083 (JP, A) JP-A-49-111686 (JP, A) JP-A-61-1986 18840 (JP, A) Actually open 58-27,760 (JP, U) JP-B 41-8040 (JP, B1)

Claims (1)

(57) [Claims] 1. An apparatus for transmitting and receiving millimeter-wave radio waves at or near a transmission line tower at a predetermined interval, and the radio waves transmitted from the transmission apparatus are attenuated by the snow quality of the snow present in the middle. A method for predicting snow accumulation on a transmission line, wherein a difference in attenuation is received and sensed by a receiving device, and a result received by the receiving device is transmitted to a monitoring place separated by using communication means.