JPH0541267A - Lightning stroke energy suppressing structure in power transmission line - Google Patents

Abstract

PURPOSE:To realize a compact size and a light weight of a lightning insulator by suppressing the direct invasion of a lightning surge current to a power transmission line, a connecting metal fitting at the voltage applying side to connect the supporting insulator and the wire of the power transmission line, and the like, so as to reduce the generating probability of an earthing accident to flashover the surface of supporting insulator from the wire and to flow to a support arm, and reducing the processing responsibility of a built-in resistance element in the lightning insulator when the lightning insulator is applied. CONSTITUTION:Power transmission lines 8 are held to the supporting arms 2 of an iron tower main body 1 through supporting insulators 5. While lightning insulators 22 are held to the supporting arms 2, an aerial earth line 9 is held to the tower top of the iron tower main body 1, and an aerial earth line 14 is held to the side of the above power transmission line 8 to the supporting arm 2 of the iron tower main body 1 through a supporting conductor 10, positioning lower than the above aerial earth line 9, and making the insulating interval L in the air with the transmission line 8 more than a standard insulating interval.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the intrusion of a lightning surge current into a transmission line and a coupling metal fitting on the side of power supply supporting the transmission line when a lightning strike occurs in the transmission line, and supports from the support insulator to the tower side. The present invention relates to a structure for suppressing lightning energy in a transmission line, which can reduce the probability of occurrence of a ground fault accident due to lightning surge flashover, and can reduce the size and weight of a lightning protection insulator when it is attached.

[0002]

2. Description of the Related Art Generally, in a support insulator device for a tower that supports a power transmission line, a support arm that is horizontally supported on a side portion of a tower body is provided with a support insulator composed of a suspension insulator series via an upper connecting fitting on the ground side. A power transmission line is supported by a lower end portion of the support insulator that is hung and is connected via a lower coupling metal fitting on the power application side and an electric wire clamp. Further, an overhead ground wire for supporting a communication function and for reducing a lightning surge current entering the tower is supported at the top of the tower body.

Further, there are the following five types of modes in which a lightning surge current enters a power transmission line during a lightning stroke. (1) When entering the middle of the overhead ground wire from above the tower, and then entering the top of the tower body.

(2) In the case of directly entering the tower top of the tower body from above the tower. (3) When entering the tip of the support arm from the side of the tower. (4) When entering the middle part of the power transmission line from the side of the steel tower and then entering the lower connecting fitting on the power distribution side.

(5) In the case of directly intruding into the lower connecting fitting on the side of the electricity application from the side of the steel tower. In recent years, in order to prevent a temporary power failure accident due to a follow current after a lightning strike in a transmission line, a tower has a voltage-current characteristic with a condition for suppressing a follow current based on an operating voltage following a lightning surge current. There is a lightning arrestor with a built-in non-linear resistance element. The lightning insulator supports a discharge electrode on the ground side which faces the discharge electrode supported on the lower connecting metal fitting on the power-supply side with a predetermined air discharge gap.

[0006]

In the above transmission line, in the case of (1) the overhead ground wire intrusion form due to the intrusion form of the lightning surge current, the upstream side with the lightning strike point of the overhead ground line as a boundary is provided. Since the lightning surge current, which is shunted to the downstream side and halved, enters the tower top of the tower main body, the current discharged to the ground through the tower main body is further reduced, so it is possible to flash over the surface of the supporting insulator. Therefore, there is no problem because the probability of occurrence of a ground fault due to a continuous current based on the operating voltage following the lightning surge current is extremely low.

Further, in the case of directly entering the tower top of the steel tower body of (2), since the lightning surge current flowing in the steel tower is increased as compared with (1), an accident of flashover on the surface of the supporting insulator in that case. The probability of increases. However, since there is a split lightning surge current that is discharged from the tower body to the ground, this is not a serious problem.

However, in the case of (3) entering the tip of the support arm, since the support insulator is present in the vicinity, flashover from the support insulator to the power transmission line side is carried out as compared with the above-mentioned tower top entry form (2). Then the probability of a ground fault accident increases.

In the case of (4) after entering the middle portion of the power transmission line and then entering the lower connecting metal fitting on the power-supply side, the lightning point of the power transmission line serves as a boundary to divide the current into the upstream side and the downstream side and halve it. Since the generated lightning surge current penetrates into the coupling metal fitting on the power-supply side, the probability of occurrence of a ground fault accident that causes a flashover from the support insulator to the support arm side increases as in (3) intrusion form.

Further, in the case of (5) intruding directly into the lower connecting metal fitting on the power-supply side or into a nearby transmission line, most of the lightning surge current will act on the supporting insulator, so that the supporting insulator will support it. The probability of flashover to the arm side and causing a ground fault is further increased compared to the intrusion form of (4).

By the way, when the lightning protection insulator is applied to the transmission line, the largest possible lightning surge current in the intrusion form of (5) among the intrusion forms of (1) to (5) described above is discharged in the air. The capacitance of the resistance element is set so that the resistance element is caused to flow to the support arm of the steel tower through the gap and the resistance element of the lightning protection insulator, and is discharged to the ground, and the subsequent current generated thereafter can be suppressed. That is, it has been necessary to use a lightning arrester provided with a resistance element having a large radial dimension capable of withstanding the largest lightning surge current. In other words, it is necessary to use a lightning protection insulator which does not cause conduction breakdown of the resistance element even when the maximum expected lightning surge current flows. The length of the resistance element is set to a predetermined length according to the voltage class of the applied transmission line.

On the other hand, the lightning surge current changes depending on the weather conditions, and a practical resistance element can be dimensioned for a normal lightning surge current. There are no problems in application to electric lines. However, when the lightning surge current is very large,
Even if the conventional design standard is used, it is difficult to use a practical size. Then, when a large lightning surge current intrudes into the vicinity of the connecting metal fitting of the support insulator on the power-charging side in the form of (5), the lightning surge current becomes the largest and it becomes very difficult to cope with it.

The present invention has been proposed to deal with the cases (3), (4) and (5) of the above-mentioned intrusion forms, and its purpose is to provide a power transmission line, a power transmission line and a support insulator. When a lightning surge current attempts to enter the power-supply-side connecting metal fittings or into the support arm, the lightning surge current is captured by an overhead grounding wire and split, and the split lightning surge current is discharged to the support arm. It is possible to reduce the probability of a lightning surge current flashing over from the support insulator to the support arm, resulting in a ground fault, and when a lightning protection insulator is attached, the responsibility of the resistance element built into the insulator against the lightning surge current. It is intended to provide a lightning strike energy suppressing structure in a power transmission line, which can reduce the size of the lightning protection insulator and reduce the size thereof.

[0014]

In order to achieve the above object, the present invention supports a power transmission line between a plurality of steel towers through supporting insulators, and supports an overhead ground wire at the top of the steel tower, An overhead grounding wire is located laterally of the power transmission line below the overhead grounding wire through a supporting conductor with respect to the tower, and an air insulation distance with the power transmission wire is equal to or greater than a standard insulation distance. Has taken the means of supporting.

[0015]

According to the present invention, by taking the above-mentioned means, a lightning surge current comes into the air from the side of a steel tower at the time of a lightning strike, and the power transmission line, the power transmission line and a supporting insulator, the vicinity of a coupling member on a power-supply side, or a support arm. Before the lightning surge current invades, it is captured by the overhead grounding wire located on the side of the tower and is shunted to the upstream side and the downstream side by the overhead grounding wire, and the split lightning surge current is connected to the overhead grounding wire. The shunt current is divided into the support conductor, and the attenuated lightning surge current flows from the support conductor to the support arm of the tower, and is discharged from the tower body to the ground. Therefore, the probability of a lightning surge current flashing over from the support arm to the grounding side connecting fitting, the surface of the supporting insulator, and the power applying side connecting fitting to cause a ground fault is reduced.

Further, when the lightning protection insulator is mounted on the support arm of the steel tower, the surge current flowing through the resistance element built in the lightning protection insulator is reduced, so the energy duty of the resistance element is reduced accordingly. The size and weight can be reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, support arms 2 are horizontally supported on the right and left sides of the tower main body 1 at three positions on one side for three-phase two-circuit, three stages on one side. As shown in FIG. 2, a supporting insulator 5 having a plurality of suspending insulators 4 connected in series through a connecting metal fitting 3 on the ground side is suspended from these supporting arms 2. A power transmission line 8 is supported on the lower end of the support insulator 5 via a coupling metal fitting 6 on the charging side and an electric wire clamp 7.

An overhead ground wire 9 for capturing lightning, which also has a communication function, is supported at the top of the tower main body 1. A support conductor 10 having a steel frame truss structure is cantilevered in a horizontal direction and in a direction orthogonal to the track on each of the support arms 2. An overhead ground wire 14 is supported on the tip of the support conductor 10 by clamp fittings 11 and 12 and a tightening bolt 13 so as to be oriented in the line direction. Further, the overhead ground wire 14 is positioned below the overhead ground wire 9 on the side of the power transmission line 8, and the air insulation distance L from the power transmission wire 8 is a standard insulation distance, that is, the support insulator 5. When the aerial insulation distance of is Z (mm), it is installed so as to satisfy the following equation.

[0019]

[Equation 1] L> 1.115Z + 21 Then, from the side of the steel tower with respect to the power transmission line 8, the power transmission line 8 and the vicinity of the power-supply-side connecting metal fitting 6 of the support insulator 5, or the support arm 2 by the overhead ground wire 14. When a lightning surge current tries to directly invade, it is captured and shunted, the current flowing through the support arm 2 is attenuated, and the probability of a ground fault accident by flashing over the creeping surface of the support insulator 5 is reduced. I am trying to do it.

On the other hand, a mounting adapter 21 is supported on the support arm 2 as shown in FIG. 2, and a lightning protection insulator 22 is suspended and fixed to the adapter 21. This lightning protection insulator 22
Incorporates a resistance element 23 whose main component is zinc oxide having a non-linear voltage-current characteristic. Further, the resistance element 23 is housed in a pressure-proof insulating cylinder (not shown), and the metal fittings 24 and 25 on the ground side and the charging side are fitted to both ends of the insulating cylinder. An insulating jacket 26 made of rubber or the like is molded on the outer peripheral portion of the pressure-proof insulating cylinder. Further, a grounding-side discharge electrode 28, which faces the power-discharging-side discharge electrode 27 supported by the power-charging-side connecting metal fitting 6 with a predetermined air discharge gap G, is supported by the power-charging-side electrode fitting 25. ing.

Next, the operation of the transmission line lightning arrester device configured as described above will be described. Now, in FIG. 1, when a lightning surge current flies from the side of the tower toward the power transmission line 8 during a lightning stroke, the overhead ground wire 14 is located outside the power transmission line 8, the support arm 2 and the connecting fitting 6. Therefore, it is captured by the overhead ground wire 14 before the lightning strikes the power transmission line 8 or the like. This lightning surge current is shunted to the upstream side and the downstream side in half at the lightning strike point of the overhead ground wire 14, and further shunted at the connection point of the support conductor 10 and the ground wire 14 to the support conductor 10. Flowing. The lightning surge current flows from the support conductor 10 to the support arm 2, and a part of the lightning surge current is split up and down in the tower main body 1, and the split lightning surge current that flows upward flows to the overhead ground wire 9. , The shunt current flowing downward is discharged to the ground.

On the other hand, the lightning surge current, which is shunted at the connection point between the support arm 2 and the lightning protection insulator 22 and attenuated to about one sixth of the first surge current, also reduces the probability itself of flowing through the lightning protection insulator 22. Therefore, the number of times of operation of the lightning arrester can be reduced. In the case of a large-scale lightning strike,
The continuous current flowing through the resistance element 23 of the lightning protection insulator 22 and the air insulation gap G to the power transmission line 8 and thereafter generated is the resistance element 2
The restoration of the resistance value of No. 3 and the air insulation gap G suppress and shut off, thereby preventing a ground fault.

Further, the shunt surge current flowing through the lightning protection insulator 22 is attenuated to about one sixth of the first lightning surge current as described above, so that the surge current from the lightning protection insulator 22 and the discharge electrode 28 on the ground side is reduced. The surge current flowing through the middle discharge gap G to the discharge electrode 27 on the charging side also becomes small,
The lightning surge current flowing to the resistance element 23 built in the lightning protection insulator 22 is reduced, and the surge current processing duty of the resistance element 23 is reduced accordingly. As a result, it is not necessary to design the resistance element 23 in consideration of the case where a large amount of lightning energy directly enters the coupling fitting 6, and the energization cross-sectional area of the resistance element 23 is reduced to reduce the size and weight of the element. The lightning insulator 22 can be manufactured at a reduced cost by implementing the manufacturing process easily.

Further, when the lightning protection insulator 22 is mounted, insulation coordination is taken so that the lightning surge current is preferentially processed on the side of the lightning protection insulator 22, but when this lightning protection insulator 22 is omitted. The lightning surge current is the first
As described above, the current is greatly attenuated. Therefore, as compared with the case where the lightning surge current directly enters the connecting metal fitting 6 on the power-supply side, the surface of the support insulator 5 is flashed over and the transmission line It is possible to drastically reduce the probability of a flow to the 8 side and a ground fault.

Next, another example of the present invention will be described with reference to FIGS. Another example shown in FIG. 3 is embodied in a crow hat type steel tower. In this another example, the overhead ground wire 9 on the tower top side
Are supported in parallel. Further, the supporting structure of the supporting conductor 10 and the overhead grounding wire 14 and the function and effect are the same as those in the above-mentioned embodiment.

In another example shown in FIG. 4, a covered lead wire 31 is connected to the overhead ground wire 14, and the lead wire 31 is led to the tower main body 1 side for connection. In this another example, the lightning surge current captured by the overhead ground wire 14 is first guided to the tower main body 1 through the overhead ground wire 14 and the lead wire 31 and is thus shunted vertically. At this time, since the surge current does not flow in the support arm 2, the surge voltage with respect to the ground is reduced, and the probability of occurrence of a ground fault accident when flashing over the creeping surface of the support insulator 5 and flowing to the electric wire side. It can be suppressed significantly. Moreover, the number of operations of the lightning protection insulator 22 can be further reduced, and the duty of the lightning protection insulator 22 can be reduced.

The present invention is not limited to the above embodiment, but may be embodied as follows. (1) In the above-described embodiment, the support conductor 10 that supports the overhead ground wire 14 is supported horizontally, but it should be supported in a forwardly-upward or forward-downwardly inclined state according to the use situation.

(2) Application to a tension-type transmission line other than the suspension-type transmission line. (3) The supporting insulator 5 itself should be configured as a power transmission line having a lightning protection function. (4) Support conductor 10 only on the important one line side of the two lines
Also, provide an overhead ground wire 14.

(5) As the lead wire 31, use is made of a plate-like or pipe-like one having a small impedance against surge current.

[0030]

As described in detail above, according to the present invention, it is possible to prevent a lightning surge current from directly intruding into a power transmission line, a metal-coupling side metal fitting for connecting a support insulator of the power transmission line and an electric wire, or a support arm. It is possible to suppress the occurrence of a ground fault accident that flows over the surface of the support insulator from the electric wire and flows to the support arm by flashover, or in the opposite direction.In addition, if a lightning insulator is applied, Has the effect of reducing the burden of processing the lightning surge current of the resistance element built into the lightning protection insulator, and making it possible to reduce the size and weight of the lightning protection insulator.

[Brief description of drawings]

FIG. 1 is a front view showing an entire transmission line support insulator device embodying a structure for suppressing lightning strike energy in a transmission line according to the present invention.

FIG. 2 is an enlarged perspective view of a support insulator device.

FIG. 3 is a front view showing another example of the present invention.

FIG. 4 is a schematic front view showing another example of the present invention.

[Explanation of symbols]

1 steel tower body, 2 support arms, 3 grounding side connecting metal fittings, 5 supporting insulators, 6 power distribution side connecting metal fittings, 8 power transmission lines,
9 overhead ground wire, 10 support conductors, 14 overhead ground wire,
22 Lightning arrester.

Claims (1)

[Claims] 1. A power transmission line is supported between a plurality of steel towers via a support insulator, an overhead grounding wire is supported on the tower top of the steel tower, and the side of the power transmission line is supported by a supporting conductor with respect to the steel tower. A structure for suppressing lightning energy in a transmission line, wherein the overhead grounding line is supported so as to be located below the overhead grounding line and the air insulation distance from the transmission line is equal to or greater than the standard insulation distance. ..