JPH06235740A - Flashover detector for steel tower for transmission line - Google Patents

Abstract

PURPOSE:To allow downsizing and simplification of a current transformer by disposing upper and lower current transformers, each having one selected main post as the primary, between an upper arm of the main post and an overhead earth-wire and between a lower arm of the main post and the earth, respectively. CONSTITUTION:Upper and lower current transformers Cu, Cd, each having a main post T4 selected according to a criterion as the primary, are disposed between an upper arm Au of the main post T4 and an overhead earth-wire G and between a lower arm Ad and the earth. When a flashover fault occurs between a power line L1m and an arm Am, for example, ground fault current Io flows by about 24(36)% through the main post T4(T1) and by 20% through T2 and T3. When a flashover fault occurs on the side of a power line L2, 20% of the current Io flows through the main post T4. Since the currents Iu and Id flow in reverse direction through the main post T4, secondary outputs of the current transformrters Cu, Cd are connected differentially at the primary of an output transformer and the secondary output is set at 24% or 20% of the current Io depending on the sum of both currents Iu, Id, or the power line side L1 or L2 where flashover fault occurred. When the integrated value of the secondary output reaches a preset value, occurrence of flashover is displayed. Downsizing and simplification of current transformer are realized by disposing current transformers each having one main post as the primary thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flashover detection device for detecting a steel tower in which a flashout accident of a transmission line has occurred, and in particular, the present invention has a simple structure and is easy to install and The present invention relates to a flash detection device with high accuracy.

[0002]

2. Description of the Related Art Electric power used not only in all industrial fields but also in many social organizations is greatly affected by power outages, and how to quickly find the location of an accident causing a power outage. Has become a major issue, and there is a strong demand for rapid and reliable detection of flashover accident towers in power transmission lines that transport electric power over long distances.

Conventionally, as a method for detecting a flashing tower, (1) a method for detecting a large lightning current flowing through the tower,
Various methods have been proposed, such as (2) a method of detecting the flashover current by comparing the directions of the flashover currents flowing through the overhead wires on both sides of the tower, and (3) a method of detecting the flashover current by attaching a current transformer to the end of the arm. .
However, these methods have the following drawbacks.

The method (1) operates also by a lightning current or a flash-to-ground fault current that intrudes from a nearby tower or an overhead ground wire other than the tower, so that the tower is not actually flashed. However, it is easy for a malfunction to detect as if a flashover occurred.

In the method (2), since the current transformer must be attached to the overhead ground wire, which is a mechanically weak component, vibration of the overhead ground wire is likely to occur and fatigue failure is likely to occur. Also, if the ground resistance of the tower is low, the flashover current flowing into the overhead ground wire will be small, which complicates the circuit for comparing the current directions and also requires another energy source such as a battery for operating the display. Will be needed. Further, in the case of a power transmission line in which an induced current is constantly flowing through the overhead ground wire, it may be difficult to compare the current directions.

In the method (3), the installation point of the current transformer is extremely close to the power line, and not only the installation work is accompanied by a power failure, but also the failure due to the flashover arc is likely to occur.

In order to solve the above-mentioned problems, one of the inventors of the present invention has previously proposed "a transmission line flash accident tower detection method" of Japanese Patent No. 1449480. This invention, in a steel tower that supports an overhead ground wire at its top, has a primary steel tower between the uppermost arm and the overhead ground wire that suspend the power line and between the lowermost arm and the ground. The upper side and the lower side current transformer which are the sides are provided, and the secondary side of these current transformers are differentially connected to constitute a detection circuit.

At the time of a flashover accident, the flashover current flowing from the accident power line into the steel tower through the armband is shunted toward the overhead ground wire and the ground, but the directions of these currents are opposite.
The current value combined on the secondary side of the upper and lower current transformers becomes a value proportional to the sum of the shunts, that is, the flashover current, and the flashover accident can be detected. On the other hand, if a lightning current from an overhead line or a flashover ground fault current in a nearby tower flows into the tower,
The currents detected by the upper and lower current transformers have the same value, the flowing directions are the same, and the secondary side of the two current transformers is differentially connected, so the output becomes 0. .

Since the above method is highly reliable and the electric energy obtained from the flashover current is large, it is possible to directly operate the display without using an auxiliary power source such as a battery.

[0010]

In the above-proposed invention, the current transformer is large in size because the entire steel tower is on the primary side, and the installation work tends to be large-scale. Further, if the current transformers are separately provided for each of the four main columns in order to reduce the size, the number of the current transformers increases and the detection circuit becomes complicated.

It is an object of the present invention to provide a flash-over power transmission line tower detector capable of reducing the number of current transformers and reducing their size and cost.

[0012]

A plurality of power lines of at least two systems are fixed to corresponding main columns at one end and the other ends are connected to each other at the apexes of upper, middle, and lower arms by means of insulators. Of the transmission line tower in which the overhead ground wire is arranged above the main pillar, and one or two main pillars selected according to the predetermined selection criteria, the upper arm and the overhead ground wire. Upper and lower current transformers having the main pillar as the primary side, respectively, between the lower arm and the ground, and the difference between the sum of the output of the upper current transformer and the sum of the output of the lower current transformer. Is detected, and the flashover accident is determined based on at least one of the value of the difference and the value representing the flashover electrical energy obtained by integrating the value of the difference for the duration of the flashover.

[0013]

[Function] The flashover current at the time of a flashover accident flows from the accident power line to the steel tower through the armband, and then splits toward the aerial ground wire and the ground, but the directions of these split currents are opposite. The difference between the upper and lower current transformers, that is, the value of the combined current becomes a value proportional to the sum of the shunt currents, that is, the flashover current, and the flashover accident is detected. On the other hand, when a lightning current from an overhead line or a flash-to-ground fault current in a nearby tower flows into the tower, the currents detected by the upper and lower current transformers have the same value and the flowing directions are the same. , These difference outputs are 0
Becomes Since one or two main pillars are provided with a current transformer having these as the primary side, the current transformer can be made compact and the installation work can be simplified. In this case, if the flashover accident is detected based on at least one of the difference output value itself and its integrated value, the flashover accident can be detected in consideration of the flashover phenomenon and the degree of damage such as an insulator. Further, since the electric energy obtained from the flashover current through the current transformer is large, the display can be directly operated without using an auxiliary power source such as a battery.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side view of an iron tower portion showing an essential part of the first embodiment of the present invention, and FIG. 2 is a structure of armpieces and reinforcing slant members of the iron tower and the arrangement of current transformers in the first embodiment. And FIG. 3 is a circuit diagram showing an electrical connection example of the upper and lower current transformers in the first embodiment.

The upper parts of the four main columns T1 to T4 constituting the steel tower are connected to each other, and an overhead ground wire G is disposed on the top part thereof. Two adjacent main pillars T1 and T4, and T2 and T3 have upper, middle, and lower arms A, respectively.
One end of u, Am, and Ad is fixed. At the apex where the other ends of the arms are connected to each other, the power line L1u is provided through the insulator S.
, L1m, L1d, etc. are hung.

The structure and shape of the armrests are the same for most of the currently used steel towers. As shown in FIG. 2, the insulator S is located at the apex A0 where the tips of the pair of armrests A1 and A2 are joined.
The power line L1 (L2) of the first (second) system is hung via the wire, and the other end of each arm is fixed to the two adjacent main pillars T1, T4 (and T2, T3), and the arm Inside the triangle formed by A1 and A2, there is provided a bracing member ST for reinforcing the braces, which is connected to one point on the braid A2, approximately the midpoint of A1 and two points near the main column, respectively. Moreover, the shapes of the upper and lower arms are similar to each other. The construction of such towers and braces is well known to those skilled in the art.

One main pillar T4 selected according to the criteria described later is provided between the upper arm Au and the overhead ground wire G and between the lower arm Ad and the ground, respectively.
The upper current transformer Cu and the lower current transformer Cd, whose primary side is C, are attached.

Now, the power line L1 on the side of the main pillars T1 and T4 in FIG.
If there is a flash accident between m and arm Am, the ground fault current I0 due to the flash will flow into the tower main pillar through this arm.

As can be easily understood from the figure, the armor A
Since the electrical impedance of the armrest from the vertex A0 connecting A1 and A2 to the main pillar at the bottom is smaller on the main pillar T1 side than on the main pillar T2 side in FIG. Flows more toward the main pillar T1 than toward the main pillar T4 than from the arm tip.
The ground fault current flows from the main pillars T4 and T1 to the main pillars T4 and T1.
In addition to shunting in the direction of the overhead ground line and in the direction of the ground, it also flows into the main pillars T3, T2 on the opposite side, and from there, further splits in the direction of the overhead ground line and the ground.

As is apparent, the current flowing through the main pillars T4, T1 near the flashed power line L1 is the main pillar T3 on the opposite side.
It is larger than the current flowing through T4. The ratio between the main pillars of the sum of the ground fault currents that shunt each main pillar upward and downward is determined by the length, cross-sectional area, and structure of the steel tower main pillars, arms, auxiliary members, but in most steel towers The similar structures and shapes described above are almost the same. The concrete values are roughly as follows according to the experimental consideration by the present inventors.
The present invention focuses on such a fact. On the flashover power line side, the main pillar on the side where the impedance is small as seen from the apex A0 of the armband pair T1 ... Approx. 36% On the flashover power line side, the impedance seen from the apex A0 of the braid pair is large. Main pillar on the side T4 ...... about 24% Main pillar on the non-flashover power line side T2, T3 ...... about 20% each As shown in FIGS. 1 and 2, the upper and lower current transformers Cu, Cd on the main pillar T4. If a flashover occurs on the power line L1 side, about 24% of the ground fault current is shunted, and if a flashover occurs on the opposite power line L2 side, 20% of the ground fault current is shunted. Since both are almost the same, it is easy to detect. In addition, since the ground fault current is generally very large, from several thousand amps to tens of thousands amps, the output of the current transformer attached only to the main pole T4 is also large, and the display can be operated directly without using external energy such as a battery. It can be done.

For this reason, in this embodiment, the secondary side outputs of the upper and lower current transformers Cu and Cd are differentially connected on the primary side of the transformer T as shown in FIG. Electrical energy store E (eg current, charge integrator) on the secondary side of T
Is connected, the stored energy is discriminated by the detector D, and the display I is driven when the stored energy exceeds a set value.

When a flashover occurs in the steel tower, the main pillar T
Current Iu flowing upward in 4 and current Id flowing downward in 4
Since the direction is opposite to, the sum of both currents, that is, 20 to 24% of the ground fault current is output to the secondary side of the output transformer T, that is, depending on which side of the power lines L1 and L2 has a flashover. It This output (current) is integrated, and when the integrated value reaches a preset value, the display I is energized to display and warn the occurrence of a flashover.

As described above, since the ground fault current is very large, the current supplied to the energy storage E is also sufficiently large, and the auxiliary power supply for operating the display I, the energy storage E and the detector D is provided. Is generally unnecessary, but it is of course possible to prepare an auxiliary power source as needed. Further, the flash detection may be detected based on the magnitude of the output itself instead of the integrated value of the output (current).

On the other hand, when electric shock or flashover occurs in the overhead ground wire or a nearby steel tower, even if the ground fault current propagating through the overhead ground wire G flows into the main pillar T4 from the top of the steel tower, Since the currents passing through the lower current transformers Cu and Cd have the same direction and substantially the same magnitude, the secondary side output of the output transformer T, which is the difference between the two currents, becomes almost zero.

In this way, the flashover tower can be detected without fail by the configuration shown in FIGS.

The ground-fault current of the transmission line depends on the neutral point ground resistance of the transformer connected to it, and the ground-fault current at the time of a flash fault decreases as the ground resistance increases. In this case, it may not be possible to drive the display I without the auxiliary power supply.

FIGS. 4 and 5 are schematic diagrams and an electric circuit showing a second embodiment of the present invention capable of increasing the ratio of the ground fault current used for detecting the ground fault and driving the display I. As shown in FIG. It is a figure. In this embodiment, as is clear from FIG. 4, among the four main pillars supporting the power lines of two systems on both sides, the main one on the side where the impedance is small as seen from the apex of the arm pair on the power line side. On columns T1 and T3,
A pair of upper and lower current transformers C1u, C1 similar to that described above.
d, C3u and C3d are provided.

Then, as shown in FIG. 5, the upper current transformer C1
u, C3u, and the lower current transformers C3d, C3d are connected in unison (in-phase) with each other, the respective currents are added, and the respective sum currents are differentially connected in the primary side of the transformer T.
In FIG. 5, the same symbols as those in FIG. 3 represent the same or equivalent parts. In addition, current transformers C3u, C3d and C1u
And C1d may be connected differentially and the sum of their differential outputs may be taken, or the secondary side of each current transformer may be directly connected to the primary side of the transformer T in consideration of the polarity. Good things are self-evident.

In FIG. 4, if a flashover occurs between one of the power lines L1 or L2 and the armature A, the ground fault current flows through each main pillar at the above-mentioned rate, so that which side of the power lines L1 and L2 is connected. Even if a flashover occurs, the ratio of the sum of the ground fault currents flowing into the main pillars T1 and T3 to the ground fault current is (36 + 2).
0)% are equal to each other.

Therefore, according to the embodiment shown in FIG. 4, even if a ground fault occurs on either side of the power line, a ground fault current having substantially the same magnitude can be captured, and a large proportion of the ground fault current is obtained as compared with the case of FIG. Since the junction current can be used, the detection level can be easily set, and the energy accumulator E such as the current integrator and the display I can be operated without an auxiliary power source.

On the other hand, when a lightning strike or a flashover occurs in the overhead line itself or another tower, the same current flows from the top to the ground in this tower, and this is the same in the pair of upper and lower current transformers. As detected, no secondary output of the transformer T is produced. Therefore, it is possible to reliably detect the flashover in the steel tower.

Further, as shown by the dotted line in FIG. 4, the main pillar T on the side where the impedance is large as seen from the apex of the pair of arms.
There may be a pair of upper and lower current transformers at 2 and T4. In this configuration, when a flashover occurs in either of the power lines L1 and L2, the ratio of the sum of the ground fault currents flowing into the main columns T2 and T4 to the ground fault current is (20 + 20)%.
Although it is somewhat smaller than the 56% of the second embodiment, it is sufficiently larger than the first embodiment of FIGS. 2 and 3, and both are equal to each other. The same effect can be expected. Even in the configuration of FIG. 5, it is natural that an auxiliary power source can be used if necessary.

A concrete example of the energy storage E, the detector D and the display I suitable for the present invention is shown in FIG. The secondary side output of the transformer T is rectified and then supplied to the integrating circuit In.
When the output of the integrating capacitor Ic exceeds the set value, the voltage relay Re is activated to drive the indicator (display, alarm) I to notify the occurrence of the flashover.

Of the flashover accidents, the one that is particularly serious is the damage to the insulator that suspends the power line.
Since the damage accident depends on the time integration of the flash current that flows when the insulator is touched, that is, the magnitude of the electric energy, the flash current is integrated by time in addition to the flash current value as in the present invention. It is rational to obtain a value proportional to energy and use this value together with the determination element, and the reliability of detection is also improved. Not only that, a surge of lightning or surge generated when the system is opened or closed may enter the power transmission line, and an abnormal voltage is likely to occur on the secondary side of the current transformer. According to the above, since they are smoothed by the energy storage device E, damage or malfunction of the device can be prevented.

[0036]

EFFECTS OF THE INVENTION Since it is sufficient to provide current transformers on the upper and lower parts of one or two main columns, the current transformer is remarkably different from the conventional technique using the current transformer having the entire tower as the primary side. The size is simplified and the installation work becomes easier. In addition, the output level detected by the current transformer pair is practically the same regardless of which side of the two transmission lines suspended in the steel tower causes a flashover, and the current changes during a flashover in another tower. The output of the instrument pair is 0
Therefore, it is easy to set the detection reference value for flashover occurrence.
Detection will be reliable. If the occurrence of a flashover is judged based on at least one of the output of the current transformer pair and the value representative of the flashover energy obtained by integrating that output for the duration of the flashover, the extent of the accident is taken into consideration. It is possible to reliably detect a flashover accident.

Although the present invention has been described with respect to the case where two power lines are supported by one steel tower, in principle, the present invention is also applicable to the case where two or more power lines are supported.

[Brief description of drawings]

FIG. 1 is a side view of a steel tower part showing a main part of a first embodiment of the present invention.

FIG. 2 is a plan view showing the structures of armrests and reinforcing diagonal members of the steel tower and the current transformer arrangement of the first embodiment.

FIG. 3 is a diagram showing an example of electrical connection between the upper and lower current transformers in the first embodiment.

FIG. 4 is a plan view of an arm member and a reinforcing diagonal member of a steel tower showing a current transformer arrangement state in a second embodiment of the present invention.

FIG. 5 is a diagram showing an example of electrical connection between the upper and lower current transformers in the second embodiment.

FIG. 6 is a circuit diagram showing a specific configuration example of an electric energy storage device and a detector suitable for the present invention.

[Explanation of symbols]

A, Ad, Am, Au ... Armband Cu ... Upper current transformer Cd
… Lower current transformer D… Detector E… Electric energy storage
I ... Indicator L1, L2 ... Power line S ... Insulator

Claims (6)

[Claims] 1. A plurality of main pillars each having an upper part coupled to each other, a plurality of armrests fixed to the main pillars, and supporting a plurality of power lines of at least first and second systems, respectively, and the main body. At least two sets of upper, middle, and lower arms are fixed to two main pillar groups adjacent to each other, each of which is composed of an overhead ground wire arranged above the pillars. A flashover detection device for a transmission line tower in which upper, middle, and lower power lines of the at least first and second systems are respectively hung at an apex whose other ends are coupled to each other via an insulator, An upper current transformer, which is provided between the upper arm and the overhead ground wire of one main pillar having the larger electrical impedance of the arm as seen, and has the one main pillar as the primary side. And provided between the lower arm and the ground of the one main pillar,
A lower current transformer having the one main pillar as a primary side, a current synthesizing means for differentially synthesizing output currents of the upper and lower current transformers, and an output of the current synthesizing means exceeding a set value. And a flashing detector for a power transmission line tower, which includes a detection unit that generates a signal indicating that a flashover has occurred in the power line tower. 2. A plurality of main pillars each having an upper part coupled to each other, a plurality of armrests fixed to the main pillars, and supporting at least a plurality of power lines of the first and second systems, respectively, and the main pillar. At least two sets of upper, middle, and lower arms are fixed to two main pillar groups adjacent to each other, each of which is composed of an overhead ground wire arranged above the pillars. A flashover detection device for a transmission line tower in which upper, middle, and lower power lines of the at least first and second systems are respectively hung via an insulator at vertices whose other ends are coupled to each other, and each system is provided. One main pillar selected from the two main pillars to which each side arm is fixed is provided between the upper arm and the overhead ground wire, and each selected main pillar is connected to the primary side. Select from the upper current transformer for each system and each system side Of said each one of the main pillars that were,
A lower current transformer for each system, which is provided between the lower arm and the ground, and has each of the selected main columns as the primary side, and the sum of all secondary side currents of the upper current transformer and the lower side A current synthesizing means for differentially synthesizing the sum of all the secondary side currents of the current transformer, and a signal indicating the occurrence of a flashover in the transmission line tower when the output of the current synthesizing means exceeds a set value. And a flashing detection device for a transmission line tower. 3. The main pillar on which each current transformer is installed is the main pillar having a larger armimpedance when viewed from the apex where the armarms are connected on each system side. A flashover detection device for a transmission line tower. 4. The main pillar on which each current transformer is installed is a main pillar having a smaller armimpedance when viewed from the apex where the armarms are connected on each system side. A flashover detection device for a transmission line tower. 5. The flashover detection device for a transmission line tower according to claim 1, wherein the current synthesizing means integrates and outputs the synthesized current. 6. A response means responsive to at least one of a value of the combined current and an integrated value of the combined current representing flashover electric energy, and energized when these values reach a preset value. The flashover detection device for a transmission line tower according to claim 5, which is a relay.