JPH0514498B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power transmission tower equipped with a lightning arrester for preventing lightning accidents on power transmission lines.

[Conventional technology]

Power transmission lines are generally equipped with overhead ground wires to prevent direct lightning strikes. However, when the lightning current increases, the potential of the steel tower, which is normally the installed potential, increases, and this voltage becomes higher than the grid voltage of the power transmission line, causing a so-called reverse flash fault. Also, depending on the state of thunderclouds, overhead ground wires may not necessarily be able to protect power lines from lightning strikes, and the lines may be directly hit. When these phenomena occur, flash shorts occur between the insulator equipment supporting the power transmission line and the arc horn installed in parallel. As a result, the grid enters a ground fault state, and ground fault current flows. Generally speaking, for such lightning accidents, a method is adopted in which the ground fault current is temporarily cut off using a circuit breaker installed in the system, and after the lightning fault has been removed, the ground fault current is turned on again.
In the case of modern power transmission lines that require high-voltage, large-capacity power transmission, the limit of power transmission capacity depends on the transient stability of the system at the time of power failure and reconnection. In order to improve transient stability, it is necessary to prevent lightning accidents from occurring, and methods of installing lightning arresters on power transmission lines have been considered. As shown in Fig. 4, this installation method involves installing a power transmission tower 1, a power transmission line 2a,
A lightning arrester 4 is installed in parallel with the insulator device 3 between the insulators 2b and 2c. In a two-circuit transmission line that performs three-phase reclosing, in order to protect one line, the upper phase 2a, middle phase 2b, and lower phase 2 on one line are always connected as shown in this figure.
It is considered to be installed at c. 5 is an arc horn, and 6 is an overhead ground wire.

[Problem that the invention seeks to solve]

As described above, conventional lightning arresters for power transmission lines are installed on each line regardless of the vertical direction, so as shown in Figures 3, 4, and 4, lightning arresters are not installed in phases where lightning arresters are not installed. There are problems in that the fault limit current is low and ground faults are more likely to occur, and the current tends to concentrate on a particular lightning arrester, increasing the energy that the lightning arrester handles and reducing its lifespan. Ta.

This invention was made to solve the above-mentioned problems, and aims to provide a power transmission tower equipped with a lightning arrester in an economical and effective way to reduce lightning accidents.

[Means for solving problems]

In the power transmission tower according to the present invention, lightning arresters are sequentially installed from the upper part of the power transmission tower to the phases.

[Effect]

In this invention, since the lightning arrester is unevenly installed in the upper phase of the transmission tower, its protective function is expanded, the flash fault limit current of the phase where the lightning arrester is not installed increases, and the lightning arrester current is increased. Imbalance is also alleviated.

〔Example〕

FIG. 1 is a diagram showing the arrangement of a lightning arrester on a steel tower according to an embodiment of the present invention. Lightning arrester 4 is 2
The upper side of the line tower 1, that is, the upper phases 2a and 21 of both lines
It is installed between the transmission line of the middle phase 2b of the single circuit and the tower 1. An arc horn 5 is provided between the power transmission lines 21b, 21c, 2c and the steel tower 1 at positions where the lightning arrester 4 is not installed.

The effect of reducing lightning accidents on power transmission lines equipped with the lightning arrester of the present invention will be explained below.

Figure 2 shows the results of calculating the arc horn flash fault limit current for each lightning arrester installation position when multiple lightning arresters are installed on a 500kv2 line tower. This high arc horn flash fault limit current means that the arc horn will not flash even at large lightning currents, making it difficult for ground faults to occur. This figure compares the influence of the installation position for 1 to 4 lightning arresters, but in all cases, the arc horn flash limit current will be higher if the lightning arresters are installed all together at the top of the tower.
For example, when three lightning arresters are installed, compared to the arc horn flash limit current when no lightning arrester is installed, if lightning arresters are installed on the upper, middle, and lower phases of one circuit, the arc horn flash limit current is approximately Although it is 1.5 times higher, if lightning arresters are installed on the upper phase of both circuits and the middle phase of one circuit, the arc horn flash limit current will be approximately 2.
It will be twice as high. The arcing horn flash fault limit current of a 500 kV power transmission line is generally about 110 kA, but if the horns are unevenly installed on the upper side of the tower as described above, this limit current becomes 220 kA. According to the statistics of lightning current, the frequency of occurrence of lightning current exceeding this value is about 0.1% of the cumulative frequency. This means that the occurrence of ground faults can be suppressed.

In addition, the phase order of each circuit of a two-line power transmission line is that when on one circuit side, the upper phase is A, the middle phase is B, and the lower phase is C, on the other line side, the upper phase is C, the middle phase is B, and the lower phase is A. The lightning arrester arrangement described above means that even if the arc horn flashes due to extremely large lightning strikes or direct lightning strikes, each of the A, B, and C phases is protected by a lightning arrester. This is convenient for power transportation.

Figure 3 shows the calculation of the lightning arrester current due to the installation of the lightning arrester. In this figure, taking the case where the number of lightning arresters installed is 3 as an example, if three layers of lightning arresters are installed on one circuit line side, the current in the lightning arrester will be approximately the same as the lightning current.
However, if a lightning arrester is installed on the upper side of the tower, that is, on the upper phase of both circuits and the middle phase of one circuit, the current flowing through the lightning arrester will be about 10% of the lightning current, reducing the energy processed by the lightning arrester. There is an effect that can be done. The same applies to other numbers of installed units.

〔Effect of the invention〕

As described below, according to the present invention, since the lightning arresters are arranged sequentially from the upper side of the tower, lightning accidents can be significantly reduced with a small number of lightning arresters.

[Brief explanation of drawings]

Figure 1 is a diagram showing the installation of a lightning arrester according to an embodiment of the present invention, Figure 2 is a diagram showing the number of installed lightning arresters and the ratio of the arc horn flash fault limit current to that without a lightning arrester, and Figure 3 is the number of installed lightning arresters. FIG. 4 is an explanatory diagram showing the relationship between lightning current and lightning current, and FIG. 4 is a layout diagram of a conventional lightning arrester. In the figure, 1 is a power transmission tower, 2a, 2b, 2
c, 21a, 21b, and 21c are power lines, and 4 is a lightning arrester. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a power transmission tower, which has a tower main body, a multi-circuit, multi-phase power transmission line installed on the tower main body, and a lightning arrester installed between some phases of the power transmission line and the tower main body, the lightning arrester A power transmission tower, characterized in that: is unevenly installed in an upper phase of the tower main body.