JP2002075060A - Overhead transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control corona discharge occurring from a tip of a water drop adhered on a conductive surface in rain. SOLUTION: The ultra water repellency is provided on the surface of a conductor by forming ultra-water-repellent film for example. By so doing, a water drop contacted on a conductor in rain is immediately repelled, and dispersed or slipped without staying on the smooth surface of the conductor so as to protect formation of a water drop projection on the surface of the conductor. This protection prevents the occurrence of the state in which the electric field becomes high at the tip of a projection on the surface of a conductor even in an electro-mechanical state, which allows protecting the occurrence of corona discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an overhead power transmission line. More specifically, the present invention relates to a state of a conductor surface of a transmission line for suppressing corona discharge generated from water droplets attached to a conductor surface of an overhead transmission line.

[0002]

2. Description of the Related Art When rainfall causes corona discharge in overhead transmission lines, noise due to corona discharge reaches the audible range, and audible corona noise problems and TV / radio reception failure due to radio noise occur in private houses along the road. There is. This phenomenon frequently occurs in a newly installed water-repellent overhead power transmission line (having water repellency due to the adhesion of oil during the manufacturing process). Generally, the surface of the conductor of an overhead power transmission line, especially an overhead power transmission line having an ultra-high voltage or higher, is formed smoothly. However, during rainfall, water droplets adhere to the surface of the conductor and form projections made of water droplets. Since the electric field is high at the tip of the protrusion on the conductor surface in the state of being charged, corona discharge is likely to occur.

[0003] Conventionally, overhead transmission lines having an ultra-high voltage or higher are multi-conductor systems (wires are arranged in parallel at intervals of several tens of cm, as shown in FIG. In general, the higher the voltage class of the transmission line, the more the number of wires increases), and the electric field strength around the conductor is reduced to suppress corona discharge.

[0004]

However, even if the electric field is reduced as a multi-conductor system, the corona discharge itself due to the adhesion of water droplets cannot be eliminated. The number of conductors must be increased from the number of conductors determined by the capacitance. In addition, the increase in the number of elementary conductors in the multi-conductor system is accompanied by the enlargement of transmission towers and the scale of construction. This leads to an increase in overhead transmission line construction costs.

[0005] It is an object of the present invention to provide an overhead power transmission line that suppresses corona discharge generated from the tip of attached water drops on a conductor surface during rainfall.

[0006]

As a result of various experiments and studies conducted by the present inventors to attain the object, the noise of corona discharge mainly generated from the tip of a water drop hanging on an electric wire shows aging indicating hydrophilicity. The new wires exhibiting water repellency remain higher than the wires (aged wires) due to the oil remaining in the manufacturing process, while the wires exhibiting super water repellency are much lower than the aged wires. Revealed.

[0007] The overhead transmission line of the present invention is based on such findings, and the conductor surface is made to have a super-water-repellent surface. Therefore, even if the conductor surface is wet with rain, water droplets are instantaneously scattered or slid down to prevent them from adhering as water droplets, so that corona discharge can be suppressed.

According to a second aspect of the present invention, the super-water-repellent surface of the overhead transmission line according to the first aspect is formed of a super-water-repellent film formed by applying a super-water-repellent material to the surface of a conductor. It is composed. In this case, a super-water-repellent surface can be easily realized only by applying a super-water-repellent material.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings.

The overhead transmission line of the present invention is configured so that the surface of the conductor 1 has super-water repellency. The super-water-repellent surface is formed, for example, by applying a super-water-repellent material to the surface of a conductor to form the super-water-repellent film 2. still,
In the present invention, the composition and structure of the conductor 1 itself are as follows.
As long as the super-water repellency of the conductor surface is not affected, there is no special composition or structure.

Here, the term super water repellency is an idiomatic term, and although not clearly defined, it generally refers to a property in which the degree of water repellency is extremely high.
It refers to a wetting phenomenon of 0 ° or more. However, the super-water repellency referred to in the present specification is not limited to the case where the contact angle θ is strictly 150 ° or more, and the water droplets 3 in contact with the conductor 1 are immediately flipped to form water droplet projections on the conductor surface. It includes all those having a water-repellent function to the extent that they can be prevented from being formed.

The surface of such a super-water-repellent conductor is coated with, for example, triacylglyceride (contact angle: 160 °), coated with alkyl ketene dimer (contact angle: 174 °), and fluorinated silane coupling is applied to the anodized surface. Anodizing method (contact angle: 167 °) treated with an agent, electrodeposition coating method using an anionic acrylic resin paint to which low-molecular PTFE (polytetrafluoroethylene) particles are added (contact angle: 171 °), polymer PTFE
Electrodeposition coating method using a cationic epoxy resin coating to which (polytetrafluoroethylene) particles are added (contact angle 15
5 °), PFA (perfluoroalkoxy fluororesin)
An electrodeposition coating method using a cationic epoxy resin paint to which particles are added (contact angle: 162 °), a chemical adsorption method in which a fluorinated surfactant is adsorbed on a plasma-etched surface (contact angle: 150 °), TFEO (tetrafluoroethylene) Oligomer) It is formed by a dispersion composite plating method (contact angle 180 °) by nickel plating to which particles are added. By these super water repellent treatment methods, a film 2 of a material having super water repellency is uniformly formed on the conductor surface. The super-water-repellent treatment method and the materials used are described above as a preferred example, but are not particularly limited thereto.

According to the overhead transmission line whose surface is super-water-repellent as described above, when the snow melts on the conductor surface during rainfall or snowfall, the water droplets 3 contacting the conductor 1 are repelled and immediately scattered or dispersed. It is possible to always prevent water droplet projections from being formed on the conductor surface by sliding down. Therefore, even in the power application state, it is possible to suppress the occurrence of corona discharge by preventing a situation in which the electric field is increased at the tip of the protrusion on the conductor surface.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, a titanium oxide photocatalyst can be applied at the time of the super-hydrophobic treatment. In this case, the superhydrophilicity, strong oxidative decomposition power, and antifouling property of the titanium oxide photocatalyst prevent the surface of the superhydrophobic material from being stained, and can extend the life.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have found that the noise of corona discharge mainly generated from the tip of a water drop hanging on an electric wire is higher in a new electric wire having water repellency than in an aging electric wire showing hydrophilicity because oil remaining during manufacturing remains. The following tests and experiments revealed that, although higher, the electric wire exhibiting super water repellency is much lower than the aged electric wire.

(1) Results of water injection test and observation of attached water drops on test wires It has been experimentally and empirically revealed that the corona noise level of transmission lines used for many years is lower than that of newly installed transmission lines. I have. This is because a newly-installed conductor (hereinafter, referred to as a new electric wire 1a) contains oil at the time of manufacture, and its surface has water repellency. On the other hand, aging (aging)
It is considered that the conductor (hereinafter, referred to as the aging electric wire 1b) which has advanced is hydrophilic, and the adhesion state of the water droplet 3 is different from that of the new electric wire 1a.

Therefore, a new electric wire 1a which contains lubricating oil as before and exhibits water repellency, and an aging electric wire 1b which has been sufficiently washed with a neutral detergent to remove oil and washed with tap water to exhibit hydrophilicity.
And a super water-repellent paint to which fluororesin fine particles are added (trade name: HIREC110 manufactured by NTT Advanced Technology Corporation)
0) is uniformly applied to the surface to produce a super-water-repellent electric wire 1c having a super-water-repellent surface, and each electric wire 1 formed when water is injected.
The shapes of the attached water droplets 3 of a, 1b, and 1c were observed. In addition, as a wire material, 810 mm ² of steel core aluminum stranded wire (ACSR) used for an ultra-high voltage transmission line was used. Further, water injection into the electric wire 1 was performed using a sprayer, so that the water droplet 3 was poured down as uniformly as possible into the electric wire, and observation of the water droplet 3 was started after sufficient water injection was performed.

(1.1) New Electric Wire FIG. 2 shows the attached water droplets 3 when water is injected into the new electric wire 1a.
The water droplet 3 that has fallen on the upper part of the electric wire flows through the groove of the electric wire 1a and is held at the lower part of the electric wire. At this time, the oil attached to the surface of the electric wire 1a exhibits water repellency, and forms a water droplet 3 having a small radius of curvature. As a result of measuring the cross section of the electric wire 1a to which the water droplet is attached, the radius of curvature of the tip of the water droplet 3 is approximately 0.22 cm (the diameter dw is approximately 0.44c).
m).

(1.2) Aging wire FIG. 3 shows the water droplets 3 attached to the aging wire 1b. Since the metal surface shows hydrophilicity, the radius of curvature of the water droplet 3 held at the lower part of the aging electric wire 1b is increased. As a result of measuring the cross section of the electric wire 1b to which the water droplet 3 adhered, the radius of curvature of the tip of the water droplet 3 was about 0.755 cm (the diameter dw was about 1.51 cm). Incidentally, the aging electric wire 1b was sufficiently dried before the water injection test.

(1.3) Super-water-repellent electric wire As shown in FIG.
Scattered as if flipped. The electric wire 1c does not contain water,
Water droplet 3 that rides on the groove of electric wire 1c like fine water droplet 3
Exists. However, the water drops 3 dropped due to slight vibration, and were not held on the electric wire 1c.

(2) Water injection test The corona characteristics of the new electric wire 1a, the aging electric wire 1b, and the super water-repellent electric wire 1c which were actually charged were confirmed.

In the test, indoor power supply equipment was used as shown in FIG. About 8 from the water injection nozzle
Water is discharged at a rate of 5 mm / h, and the water falls almost uniformly on the test wire 1. Test wire 1 is 50cm at the bottom of wire and zero potential surface
It was overhead line to keep the distance.

[0023] The noise level is determined by the 10
Because the noise of the 0 Hz component was at a high level,
Noise level of A characteristic up to about kHz is measured with a precision sound level meter (R
ION Corporation NA-61).

FIG. 6 shows that the Gmax (gradient of the maximum conductor surface potential, which is the maximum electric field value) of the electric wire surface during drying is 16 kV / cm.
The results of the corona noise measurement under the condition where the power was applied so that The test wire 1 is a new wire 1a and an aging wire 1 which have been subjected to the same surface treatment as the wire 1 shown in the above (1).
b, Super-water-repellent electric wire 1c, the corona noise level was measured at the time of drying, at the time of pouring water, and after stopping pouring water.

Since the outer shape of the wire 1 subjected to each treatment does not change, the electric field distribution and the amount of corona discharge generated on the test wire surface during drying do not change. Careful attention was paid so that the noise level at the time of drying of the overhead wire of the test wire 1 did not vary depending on the installation state of the test equipment. The noise level during drying includes noise and background noise generated from power application equipment in addition to the test wire 1,
Later comparisons were made based on the noise levels including these.

The noise level at the time of water injection includes the sound of water injection, but the noise level is highest for the new electric wire 1a and lowest for the super water-repellent electric wire 1c. In the super water-repellent electric wire 1c, it was visually confirmed that corona discharge was slightly generated at the contact portion with the water droplet 3 at the upper part of the electric wire, but no corona discharge was generated at the lower part of the electric wire. The new electric wire 1a and the aging electric wire 1b were violent from the attached water drops 3 at the lower part of the electric wire, and corona discharge was constantly generated. Focusing on the change in the noise level after the stop of the water injection, the amount of drop of the water droplet 3 attached to the new electric wire 1a is small, and therefore, the reduction amount of the noise level with the passage of time is small. After the water injection is stopped, water droplets 3
Therefore, the noise level immediately after the stop of water injection decreases to near the noise level during drying.

In the above test, since the length of the test wire was short and a measurement system for removing noise generated from the test equipment was used, the amount of noise and corona hum generated at the actual scale could not be measured. This is considered to indicate that the water wire 1c is an effective countermeasure against corona noise. From this, it was proved that the application of the super water-repellent electric wire was effective as a measure for reducing the number of elementary conductors of the multi-conductor system and as a measure against corona noise during rainfall. At the same time, since the super-water-repellent electric wire does not adhere to water droplets and slides down without icing or snow, it can be used as a measure against icing and snow without maintenance.

[0028]

As is apparent from the above description, according to the overhead transmission line according to the first aspect, since the conductor surface has a super water repellent function, even if the conductor surface is wet with rain, water droplets are instantaneously formed. Prevents water droplets from scattering or sliding down to the bottom of the conductor, and prevents water droplets from forming on the surface of the conductor even when power is being applied, preventing the electric field from increasing at the tip and preventing corona discharge. can do.

Therefore, radio wave noise and corona noise caused by corona discharge can be reduced. Also,
Even when the multiconductor method is adopted, an overhead power transmission line that ignores corona noise can be designed, and the number of conductors can be reduced to the number of elementary conductors determined by the power transmission capacity. The reduction in the number of elementary conductors in the multi-conductor system prevents transmission line towers in ultra-ultra-high-voltage transmission from becoming huge and large-scale construction, and enables overhead transmission line construction costs to be reduced. That is, the electrical environment design of the transmission line, which has been designed in consideration of the occurrence of corona discharge, is changed, the size of the transmission line can be reduced, the construction period can be shortened, and the cost can be reduced.

According to the overhead transmission line of the second aspect, since the super-water-repellent material is applied to the conductor surface to form the super-water-repellent film, it can be continuously and uniformly applied in the electric wire manufacturing process. A super water-repellent surface can be easily formed.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an overhead transmission line showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a new electric wire and water drops.

FIG. 3 is a cross-sectional view showing an aging electric wire and water drops.

FIG. 4 is a sectional view showing a super-water-repellent electric wire injected with water.

FIG. 5 is a diagram schematically showing a configuration of a water injection charge test apparatus.

FIG. 6 is a graph showing an example of a corona noise measurement result.

FIG. 7 is a diagram showing an example of arrangement of elementary conductors in a conventional multiconductor system.

[Explanation of symbols]

 1 electric wire (conductor) 2 super water repellent film 3 water drop

Claims (2)

[Claims] 1. An overhead power transmission line, wherein the surface of the conductor is a super water-repellent surface. 2. The overhead transmission line according to claim 1, wherein the super-water-repellent surface is formed by applying a super-water-repellent material to a surface of a conductor to form a super-water-repellent film. .