CN109390897B - An overhead ground wire based on ground wire tensioning method and ground wire tension insulator - Google Patents
An overhead ground wire based on ground wire tensioning method and ground wire tension insulator Download PDFInfo
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- CN109390897B CN109390897B CN201811516608.4A CN201811516608A CN109390897B CN 109390897 B CN109390897 B CN 109390897B CN 201811516608 A CN201811516608 A CN 201811516608A CN 109390897 B CN109390897 B CN 109390897B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G7/00—Overhead installations of electric lines or cables
- H02G7/22—Arrangements of earthing wires suspended between mastheads
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G7/00—Overhead installations of electric lines or cables
- H02G7/02—Devices for adjusting or maintaining mechanical tension, e.g. take-up device
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G7/00—Overhead installations of electric lines or cables
- H02G7/16—Devices for removing snow or ice from lines or cables
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Abstract
The invention provides an overhead ground wire based on a ground wire tension-open mode and a ground wire tension-resistant insulator, which comprises the following components: ground wire, ground wire strain insulator and ground wire jumper; the ground wire is connected with a circuit tower in an open tension connection mode; the ground wire tension insulator is horizontally connected between the ground wire and the circuit tower; the electrical parameter of the ground wire tension insulator is larger than or equal to the electrical parameter of a wire insulator of a power transmission line where the ground wire tension insulator is positioned; the ground wire jumper is in an electric insulation state or an electric connection state with the ground wire. When the ground wire jumper is in an electric insulation state with the ground wire, the invention can greatly reduce the wire-ground wire discharging tripping times of the overhead transmission line under severe rain, snow, ice and east weather conditions, and the number of broken wires and inverted towers of the ground wire possibly caused by discharging.
Description
Technical Field
The invention relates to the technical field of power transmission, in particular to an overhead ground wire based on a ground wire tension-open mode and a ground wire tension-resistant insulator.
Background
Overhead transmission lines (lines for short) are an important component of the power grid. The severe ice-coating of the wires and the ground wires under the weather conditions of rain, snow and ice can lead to the discharge, disconnection and tower inversion of the wires, even cause large-area power failure of the power grid, and seriously threaten the safe and stable operation of the power grid.
Taking a Jibei power grid in the North China power grid ice disaster in 2015 as an example, combining the North China power grid ice disaster in 2005 with the North China power grid ice disaster in 2008, and analyzing the formation process of the power transmission line ice disaster and the weak links of the line under the rainy, snowy and frozen weather conditions.
(1) Wire-ground discharge: under severe rain, snow and ice conditions, severe ice and snow coverage can be formed on the wires and the ground. The wire and the wire are covered with ice and snow, which can cause the wire to stretch elastically, the wire and/or the wire to deviate along the wire, the wire and/or the wire to break ice and jump, the wire support to damage and deform, the wire to slide along the suspension clamp and the like, wherein one or a combination of the cases can cause the air gap between the wire and the wire to discharge, the number of the discharge related to the wire accounts for 96% of the trip of the Jibei power grid line in the 2015 ice disaster, and the discharge ratio between the wire and the wire can also reach 40-60% in the 2005 ice disaster and the 2008 ice disaster; the rest of the lines are tripped mainly by the discharge of the insulator. The problem of insulator discharge can be easily solved by improving the insulator configuration, but wire-ground wire discharge is a long-standing problem. The following specifically illustrates 5 cases that occur after wire and ground wire ice coating:
① Elastic elongation of ground wire: the ground wire is covered with ice, the tension is increased, elastic elongation is generated, and sag is increased. Since the ground wire is generally mounted above or obliquely above the wire, the wire-to-ground wire spacing decreases as the sag of the ground wire increases, possibly causing discharge.
② The ground wire and/or the lead wire are offset along the wire:
under the general operating condition, the ground wire tension on two sides of the line tangent tower is equal, and the hardware fitting (and the ground wire insulator) for hanging the ground wire is in a vertical state. When the ground wires on the two sides are unevenly covered with ice and snow or the gaps between the two sides are large although the ice and snow are evenly covered, the ground wires on the two sides generate tension difference, so that the ground wires are deviated to the side with large tension, and the ground wire fittings (and the ground wire insulators) are inclined to the side with large tension. The deflection of the ground wire can lead to the large increase of the ground wire sag at the side with larger tension, the space between the lead and the ground wire is reduced, and the discharge is easy to be caused.
Similar to the ground wire, when the wires at two sides of the tangent tower are unevenly coated with ice and snow or the gaps between the two sides are larger although the wires are evenly coated with ice and snow, the wires at the two sides generate tension difference, the wires are deviated to one side with larger tension, the sag of the wires at the side with smaller tension is greatly reduced, the distance between the wires and the ground wire is reduced, and discharge is easily caused.
③ Ground wire and/or wire deicing skip: when the ice coating of the wire or the ground wire falls off in a large area, ice-removing jump occurs, the distance between the wire and the ground wire is dynamically and greatly changed, and discharge is easily caused.
④ Damage deformation of the ground wire support: when the ground wire is covered with ice and snow, the ground wire support will bear increased vertical load; when the ground wires on both sides of the tangent tower are unevenly coated with ice and snow, the ground wire support will bear horizontal load (i.e., longitudinally unbalanced tension). When the vertical and horizontal loads exceed the bearing capacity of the ground wire support, the support is damaged and deformed and deviates to the side with higher tension. The effect of the deviation of the ground wire support is the same as that of the direct ground wire deviation of ②, so that the ground wire sag of the side with larger tension is greatly increased, the space between the wires and the ground wires is reduced, and discharge is easy to cause.
⑤ The ground wire slides along the suspension clamp: when the ground wires on both sides of the tangent tower are unevenly coated with ice and snow, the suspension clamps suspending the ground wires will bear horizontal load (i.e., longitudinal unbalanced tension). When the horizontal load exceeds the grip of the suspension clamp, the ground wire will slip along the suspension clamp to the side where the tension is greater. The sliding is the same as the direct ground wire shifting effect of ②, so that the ground wire sag at the side with larger tension is greatly increased, the space between the wires and the ground wires is reduced, and the discharge is easily caused.
Summary 1 discharge statistics between wire-ground indicate: the ground wire (including the ground wire bracket, the ground wire connection mode and the like) is a weak point of the line during the ice disaster of the power grid.
(2) Broken ground wire: in the ice disaster of the North China electric network in 2015, the ground wire broken line (including the optical fiber composite overhead ground wire OPGW) occurs on 3 500kV lines and 1 220kV line of the North China electric network, and the ground wire broken line point is also a discharge point of a lead-ground wire. On one hand, under the weather conditions of rain, snow and ice, the tension of the ground wire is greatly increased due to ice and snow covering; on the other hand, the high temperature generated by the discharge between the wire and the ground wire may lower the local mechanical strength of the ground wire discharge point by 50%. But the calculations indicate that: the single mechanical strength reduction factor and the single tension increase factor can not cause broken ground wires; only when two factors act on the ground wire simultaneously, the broken wire condition can be provided.
The statistics of broken ground wire of the small junction 2 show that: the ground wire (including the ground wire bracket, the ground wire connection mode and the like) is a weak point of the line during the ice disaster of the power grid.
(3) And (3) pouring: when the line tower is subjected to a vertical load or a horizontal load (i.e., a longitudinal imbalance tension) that exceeds a design threshold, a tower collapse may result, wherein the longitudinal imbalance tension is a relatively greater threat to the line tower. Under severe rain, snow and ice weather conditions, line inversion generally occurs in a string, wherein a base tangent tower with weak longitudinal unbalanced tension tends to become an inversion starting point, the inversion is transferred to an adjacent tangent tower through tension of wires and ground wires, longitudinal unbalanced tension is generated, and further inversion is performed, and the inversion process forms a chain reaction until a strain tower with large longitudinal unbalanced tension can be born (for example, 319 base inversion of 21 500kV lines in ice disaster of a power grid in 2008).
The following emphasis analysis is made on the reason of the falling of the tangent tower as the starting point of the series of falling towers, including: ① The vertical load formed by the ice and snow covered by the wires and the ground wires at the two sides of the line tower exceeds a design threshold value so as to crush the tower; ② The wires or the ground wires at two sides of the line tower are unevenly covered with ice and snow, and the formed longitudinal unbalanced tension exceeds a design threshold value to turn over the tower; ③ The wire or the ground wire on one side of the line tower is broken, and the formed longitudinal unbalanced tension exceeds a design threshold value to reverse the tower. Inverted towers are typically the result of a combination of vertical and horizontal loads (i.e., longitudinal imbalance tension), but longitudinal imbalance tension tends to act to directly trigger the inverted tower, with a relatively greater threat to the line tower.
The relationship of the ground wire (including ground wire discharge, ground wire breakage) to the first base tower is further analyzed as follows: ① As described above, the wire-ground wire discharge trip ratio in ice disaster is high, and the line is easily stopped due to low reclosing success rate in ice disaster. Under severe rain, snow and ice weather conditions, the wire stops transmitting electric energy after the line is stopped, and the resistive heating of the wire is interrupted, so that the icing of the wire is accelerated, the tension of the wire and the mechanical load (including vertical load and horizontal load) borne by a line tower are increased, and the reverse tower is more easily caused, namely, the mechanical load of the line tower can be indirectly increased and the reverse tower is caused when the line is stopped due to ground wire discharge. ② As mentioned above, wire-to-ground wire discharge in ice disasters is a direct contributor to ground wire breakage, which would subject the tower to the impact of a dynamic horizontal load that would tend to directly trigger tower collapse for towers that are already under critical mechanical loads during ice disasters. The analysis report of the Hunan electric network and the like in the ice disaster in 2008 confirms the analysis: ① The tower falling in the ice disaster basically occurs after the line is stopped, and the reasons for the line to stop include that OPGW optical cable and overhead ground wire ice coating sag is reduced … …; ② "recovering 21 running lines with diseases during reconstruction, … …, wire damage 1, ground wire damage 4, optical cable damage 21, … …"; ③ The method has the advantages that a batch of temporary emergency power transmission measures for cutting off the ground wire operation and the like are provided for the line which is damaged and stopped, and the method plays a very positive role in maintaining the operation of a main power grid; ④ Particularly, under the weather conditions of rain, snow and freezing, part of the lines are used as important measures for maintaining the operation of the power grid, wherein the part of the lines directly fall down to the ground line.
Summary 3 reverse tower statistics again indicate: the ground wire (including a ground wire bracket, a ground wire connection mode and the like) is a line weak point during the ice disaster of the power grid, and is a direct reason for one part of tower inversion and an indirect reason for the other part of tower inversion.
In summary, the ground wire (including the ground wire bracket, the ground wire connection mode, etc.) is a weak point of the line during the grid ice disaster. Therefore, how to overcome the weak points in the existing power transmission line to cope with the influence of rain, snow and freezing weather on the safe operation of the power transmission line is a technical problem to be solved currently.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the overhead ground wire based on the ground wire tension-open mode and the ground wire tension-resistant insulator, which greatly reduces the wire-ground wire discharge tripping times of the overhead power transmission line under severe rain, snow, ice and east weather conditions, reduces the number of broken wires and inverted towers of the ground wire possibly caused by discharge, improves the ice resistance of the line, and has the advantages of low investment and high cost performance.
In order to achieve the above object, the present invention provides an overhead ground wire based on a ground wire open strain mode and a ground wire strain insulator, the overhead ground wire comprising: ground wire, ground wire strain insulator and ground wire jumper;
The ground wire is connected with a circuit tower in an open tension connection mode;
The ground wire tension insulator is horizontally connected between the ground wire and the circuit tower; the electrical parameters of the ground wire tension insulator are greater than or equal to those of a wire insulator of a transmission line where the ground wire tension insulator is positioned;
the ground wire jumper wire is in an electric insulation state or an electric connection state with the ground wire.
In an embodiment, when the ground wire jumper is in an electrical insulation state with the ground wire, the insulation strength between the ground wire jumper and the ground wire is greater than or equal to the insulation strength of the ground wire tension insulator, and the anti-icing operation mode is used.
In an embodiment, the lightning protection device is used for lightning protection operation when the ground wire jumper is in an electrical connection state with the ground wire.
In one embodiment, the connection mode of the ground wire jumper and the circuit tower includes: the ground wire jumper is connected directly with the line tower or with a conventional ground wire insulator connected in parallel with the discharge gap of the ground wire.
In one embodiment, the ground wire tension insulator includes: rod-shaped suspension composite insulator, disc-shaped suspension porcelain insulator, disc-shaped suspension glass insulator and rod-shaped suspension porcelain insulator.
In an embodiment, the connection mode of the ground wire tension insulator includes: a single insulator type and a multiple insulator type.
In one embodiment, the circuit tower includes: a tangent tower and a strain tower.
In one embodiment, the circuit tower is at least two-base circuit tower.
The application provides an overhead ground wire based on a ground wire tension-open mode and a ground wire tension-resistant insulator, which comprises the following components: ground wire, ground wire strain insulator and ground wire jumper; the ground wire is connected with a circuit tower in an open tension connection mode; the ground wire tension insulator is horizontally connected between the ground wire and the circuit tower; the electrical parameter of the ground wire tension insulator is larger than or equal to the electrical parameter of a wire insulator of a power transmission line where the ground wire tension insulator is positioned; the ground wire jumper is in an electric insulation state or an electric connection state with the ground wire. When the ground wire jumper is in an electric insulation state with the ground wire, the application can greatly reduce the wire-ground wire discharging tripping times of the overhead transmission line under severe rain, snow, ice and east weather conditions, and the number of broken wires and inverted towers of the ground wire possibly caused by discharging.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an overhead ground wire directly electrically connected to a line tower with a ground wire jumper in a lightning protection mode of operation of the present invention;
FIG. 2 is a schematic diagram of an overhead ground wire directly electrically connected to a line tower with a ground wire jumper in an anti-icing mode of operation in accordance with an embodiment of the present invention;
FIG. 3 is a schematic diagram of an overhead ground wire in which a ground wire jumper is directly and electrically connected to a tower during a lightning protection operation mode according to an embodiment of the present invention, and further the ground wire jumper is connected to the tower by a parallel groove clamp to enhance the electrical connection performance between the ground wire jumper and the tower;
FIG. 4 is a schematic diagram of an overhead ground wire in which a ground wire jumper is directly electrically connected to a tower during an anti-icing mode of operation and further the ground wire jumper is connected to the tower with a parallel groove clamp to enhance the electrical connection between the ground wire jumper and the tower;
FIG. 5 is a schematic view of a conventional ground insulator in parallel with the discharge gap for connecting a ground jumper to an overhead ground wire of a line tower in a lightning protection mode of operation in accordance with an embodiment of the present invention;
FIG. 6 is a schematic diagram of an overhead ground wire with a conventional ground wire insulator in parallel with the discharge gap for connecting a ground wire jumper to a line tower in an anti-icing mode of operation in accordance with an embodiment of the present invention;
FIG. 7 is a schematic view of an overhead ground wire for two adjacent towers in an anti-icing mode of operation according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of an overhead ground wire for two adjacent strain towers in an anti-icing mode of operation in accordance with an embodiment of the present invention;
fig. 9 is a schematic structural view of overhead ground wires for adjacent ones of a foundation tangent tower and a foundation strain tower in an anti-icing mode of operation in accordance with an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms "first," "second," … …, and the like, as used herein, do not denote a particular order or sequence, nor are they intended to be limiting of the invention, but rather are merely used to distinguish one element or operation from another in the same technical terms.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
As used herein, "and/or" includes any or all combinations of such things.
Technical term interpretation:
overhead conductor: the device for transmitting electric energy in overhead transmission lines is simply called a wire.
Overhead ground wire: the device for preventing lightning from directly striking the lead in the overhead transmission line is generally arranged above or obliquely above the lead, and is called a ground wire for short and a lightning conductor for short.
Tension tower: the tower type overhead transmission line has strong capability of bearing horizontal load and vertical load.
Straight line tower: a tower type overhead transmission line has stronger capability of bearing vertical load, but weaker capability of bearing horizontal load.
Wire insulator: an insulator for connecting conductors of an overhead transmission line to a line tower and capable of withstanding voltage and mechanical forces between the conductors and the line tower that meet design requirements.
Aiming at the defects in the prior art, the invention provides an overhead ground wire (hereinafter referred to as overhead ground wire) based on a ground wire tension-open mode and a ground wire tension-resistant insulator, the structure schematic diagram of which is shown in figure 1, the overhead ground wire comprises: ground wire 1, ground wire strain insulator 2 and ground wire jumper 3.
The ground line 1 is connected to the line tower 4 in an open tension connection (also referred to as a horizontal connection).
The ground wire tension insulator 2 is horizontally connected between the ground wire 1 and the circuit tower 4. The electrical parameter of the ground wire tension insulator 2 is larger than or equal to the electrical parameter of the wire insulator 5 of the transmission line where the ground wire tension insulator 2 is positioned. The electrical parameter is specifically an electrical parameter other than the atmospheric overvoltage, which is not limited by the present application.
The ground wire jumper is in an electrically insulating state (i.e., a state without electrical connection) or an electrically connecting state (i.e., a state with electrical connection) with the ground wire.
In one embodiment, as shown in fig. 1, the lightning protection operation mode is used when the ground jumper 3 is in an electrical connection state with the ground 1. The lightning protection operation mode is suitable for meteorological conditions which cannot cause ice disaster of the power grid, and the overhead ground wire in the lightning protection operation mode has a conventional lightning protection function.
In one embodiment, as shown in fig. 2, when the ground wire jumper 3 and the ground wire 1 are in an electrically insulating state, the insulating strength between the ground wire jumper 3 and the ground wire 1 is equal to or greater than the insulating strength of the ground wire tension insulator, and the anti-icing operation mode is used. The overhead ground wire in the anti-icing operation mode is suitable for rain, snow and freezing weather conditions possibly causing ice disaster of the power grid, and the anti-icing operation mode can avoid wire and ground wire between wires and ground wires caused by ice and snow covering of the wires and the ground wires and ground wire broken wires and tower falling possibly caused by the discharge.
In one embodiment, the manner in which the ground jumper 3 is connected to the line tower 4 includes: the ground jumper 3 is connected directly to the line tower 4 or the ground jumper 3 is connected to the line tower 4 with a conventional ground insulator 8 connected in parallel with the discharge gap 7 of the ground.
In specific implementation, as shown in fig. 3, the ground wire jumper 3 is directly connected to the line tower 4 (including the tangent tower and/or the strain tower), and meanwhile, the parallel groove clamp 6 is used to connect the ground wire jumper 3 to the line tower 4 to further ensure good electrical connection performance, and at this time, the overhead ground wire is in a lightning protection operation mode.
As shown in fig. 4, the ground wire jumper 3 is directly connected to the line tower 4 (including the tangent tower and/or the strain tower), and meanwhile, the parallel groove clamp 6 is used for connecting the ground wire jumper 3 to the line tower 4 to further ensure good electrical connection performance, and the overhead ground wire is in an anti-icing operation mode.
As shown in fig. 5, the ground jumper 3 is connected to the line tower 4 (including the tangent tower and/or the strain tower) with a conventional ground insulator 8 connected in parallel with the discharge gap 7, and the overhead ground wire is in a lightning-protection mode of operation at this time.
As shown in fig. 6, the ground jumper 3 is connected to the line tower 4 (including the tangent tower and/or the strain tower) with a conventional ground insulator 8 connected in parallel with the discharge gap 7, and the overhead ground wire is in an anti-icing mode of operation at this time.
In one embodiment, the ground wire tension insulator 2 includes: the invention is not limited to a rod-shaped suspension composite insulator, a disc-shaped suspension porcelain insulator, a disc-shaped suspension glass insulator and a rod-shaped suspension porcelain insulator.
In one embodiment, the connection manner of the ground wire tension insulator 2 includes: a single insulator type and a multiple insulator type.
Specifically, the single-connection insulator mode is to use only one insulator or one insulator string in a rod-shaped suspension composite insulator, a disc-shaped suspension porcelain insulator or a disc-shaped suspension glass insulator as the ground wire tension insulator 2.
The multi-insulator mode is usually that a plurality of insulators of the same type or a plurality of insulator strings of the same type are connected in parallel to be used as the ground wire tension insulator 2.
In one embodiment, the wiring tower 4 includes: a tangent tower 10 and a strain tower 11.
In one embodiment, the wiring tower 4 is at least a two-base wiring tower.
In particular, the application range of the overhead ground wire is two adjacent line towers or a continuous multi-line tower. The line towers 4 may be linear towers and/or strain towers, or the line towers 4 may be of the same type or different types, which is not limited by the present invention.
Fig. 7 is a schematic structural view of the overhead ground wire of the present invention applied to two adjacent towers and in an anti-icing mode. The ground jumper 3 is directly electrically connected to the line tower 10. At this time, the ground wire jumper 3 is detached from the connection fitting (such as a drainage plate of a ground wire strain clamp, etc.) of the ground wire 1 and is fixed on the line tower 10, namely, the ground wire 1 and the ground wire jumper 3 are electrically insulated, and the insulation strength (including the ground wire strain insulator and the air gap) between the ground wire 1 and the line tower 10 can bear line phase voltage and operation overvoltage because the electrical parameter (excluding the atmospheric overvoltage parameter) of the ground wire strain insulator 2 is greater than or equal to the electrical parameter of the conductor insulator 5 of the overhead transmission line. In this operation mode, the wire 9-ground wire 1 cannot be discharged due to the elastic elongation of the ground wire 1 caused by the ice coating of the wire 9 and the ground wire 1, the deviation of the ground wire 1 and/or the wire 9 along the wire, the separation between the wire 9 and the ground wire 1 caused by the ice removing jump of the wire 1 and/or the wire 9, and accordingly the subsequent wire breakage and tower inversion of the ground wire caused by the discharge are avoided.
The overhead ground wire changes the suspension connection mode of the ground wire 1 of the tangent tower 10 into the open tension connection mode (also called horizontal connection mode), so that the mechanical strength of the tangent tower 10 is improved only aiming at the increase of the mechanical load from the ground wire 1, the influence on the engineering cost is limited, and the overhead ground wire has comprehensive popularization and application values. At present, the measure for improving the whole ice-resistant grade of the circuit tower 4 needs to improve the mechanical strength of the tangent tower aiming at the increase of the mechanical load from the ground wire 1 and the lead wire 9, has great influence on engineering cost, is difficult to comprehensively popularize and apply, and can not solve the problem of lead wire-ground wire discharge tripping during ice disaster although the ice-resistant grade of the circuit tower is improved.
Fig. 8 is a schematic structural view of the overhead ground wire of the present invention applied to two adjacent strain towers and in an anti-icing mode. The ground jumper 3 is directly electrically connected to the line tower 11. The discharge between the lead and the ground wire cannot be caused due to the reduced spacing between the lead 9 and the ground wire 1 caused by the ice coating of the lead 9 and the ground wire 1, and accordingly, the ground wire breakage and the tower falling possibly caused by the discharge are avoided.
The overhead ground wire does not change the ground wire opening tension connection mode (also called horizontal connection mode) of the tension tower 11, so that the mechanical strength of the tension tower 11 is not required to be improved basically, and only the electric parameters (excluding the atmospheric overvoltage parameters) of the ground wire tension insulator 2 of the tension tower 11 are required to be more than or equal to the electric parameters of the wire insulator 5 of the overhead transmission line where the tension tower 11 is positioned, so that the influence on the construction cost is negligible, and the method has comprehensive popularization and application values.
Fig. 9 is a schematic structural view of the overhead ground wire structure of the present invention applied to an adjacent foundation tangent tower and foundation strain tower in an anti-icing operation mode. The ground jumper 3 is directly electrically connected to the line towers 10 and 11. The discharge between the lead and the ground wire cannot be caused due to the reduced spacing between the lead 9 and the ground wire 1 caused by the ice coating of the lead 9 and the ground wire 1, and accordingly, the ground wire breakage and the tower falling possibly caused by the discharge are avoided.
The invention provides an overhead ground wire based on a ground wire tension-open mode and a ground wire tension-resistant insulator, which comprises the following components: ground wire, ground wire strain insulator and ground wire jumper; the ground wire is connected with a circuit tower in an open tension connection mode; the ground wire tension insulator is horizontally connected between the ground wire and the circuit tower; the electrical parameters of the ground wire tension insulator are more than or equal to those of the wire insulator of the power transmission line where the ground wire tension insulator is located (excluding the atmospheric overvoltage parameter); the ground wire jumper is in an electric insulation state or an electric connection state with the ground wire.
The overhead ground wire of the present invention includes: an anti-icing operation mode and a lightning protection operation mode. The anti-icing operation mode is suitable for rain, snow and freezing weather conditions possibly causing grid ice disaster, and the ground wire jumper and the ground wire in the anti-icing operation mode are in an electric insulation state (namely a state without electric connection), so that discharge between a wire and the ground wire caused by ice and snow covered on the wire and the ground wire, and wire breakage and tower falling of the ground wire possibly caused by the discharge can be avoided. The lightning protection operation mode is suitable for other meteorological conditions, and the ground wire jumper and the ground wire in the lightning protection operation mode are in an electric connection state, so that the lightning protection device has a conventional lightning protection function. The invention is an anti-icing measure of overhead transmission line (short line) with good effect and less investment, and can achieve the effect of half effort in the anti-icing work of the power grid.
Meanwhile, the invention has the following advantages:
1. Compared with the prior measures for improving the whole ice resistance of the circuit body, the invention greatly reduces engineering investment.
The invention connects the ground wire to the circuit tower in an open tension connection mode through the ground wire tension insulator, and the circuit tower comprises a tangent tower and a tension tower.
① The strain tower is a circuit tower for supporting and fixing wires, and has strong capacity of bearing horizontal load and vertical load. For the strain tower, the original open strain connection mode of the ground wire is not changed, so that the structure, the size, the mechanical strength and the manufacturing cost of the existing strain tower are less in change.
② The tangent tower is also a line tower for supporting and fixing wires, and has strong capability of bearing vertical load, but weak capability of bearing horizontal load. For the tangent tower, the original suspension connection mode of the ground wire is changed into an open tension connection mode, and the mechanical load born by the tangent tower and derived from the ground wire is increased, so that the mechanical strength of the conventional tangent tower, particularly the mechanical strength of a ground wire bracket, is correspondingly improved, and the manufacturing cost of the tangent tower is correspondingly improved; however, compared with the anti-icing measures which are widely used at present and improve the overall mechanical strength of the tangent tower, the tangent tower of the present measure needs to consider the increase of the mechanical load from the ground wire and the increase of the mechanical load from the lead wire, and the mechanical load from the lead wire is a main factor influencing the mechanical strength and the manufacturing cost of the tangent tower, so the increase of the manufacturing cost and the engineering cost of the iron tower of the present invention is obviously lower than that of the present measure.
③ In the lightning protection operation mode, the ground wire jumper is electrically connected with the ground wire through the hardware fitting (such as the drainage plate of the ground wire strain clamp), and as shown in fig. 1, 3 and 5, the ground wire jumper has no insulation distance requirement with the line tower and has no insulation distance requirement with the ground wire strain insulator, namely the invention does not need to greatly improve the tower head size of the existing line tower and does not need to obviously increase the engineering cost.
2. Compared with the existing anti-icing measures such as 'directly falling down the ground wire to run' and the like of some power grids during ice disaster, the anti-icing running mode only relates to the disassembly and assembly of the ground wire jumper; the assembly and disassembly of the ground wire jumper can be combined with the power grid ice disaster early warning system, namely, the assembly and disassembly of the ground wire jumper and the conversion of the operation mode can be carried out only when the early warning system issues very few severe weather conditions of the ice and rain disasters. Thus, the workload during line operation is greatly reduced.
3. The invention effectively avoids the problem that the existing AC/DC ice melting technology is difficult to be used for the overhead ground wire.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (6)
1. An overhead ground wire based on ground wire open strain mode and ground wire strain insulator, characterized in that includes: ground wire, ground wire strain insulator and ground wire jumper;
The ground wire is connected with a circuit tower in an open tension connection mode;
The ground wire tension insulator is horizontally connected between the ground wire and the circuit tower; the electrical parameters of the ground wire tension insulator are greater than or equal to those of a wire insulator of a transmission line where the ground wire tension insulator is positioned;
the ground wire jumper is in an electric insulation state or an electric connection state with the ground wire;
when the ground wire jumper is in an electric insulation state with the ground wire, the insulation strength between the ground wire jumper and the ground wire is larger than or equal to the insulation strength of the ground wire tension insulator, and the anti-icing operation mode is adopted;
When the ground wire jumper is in an electrical connection state with the ground wire, the lightning protection device is used for a lightning protection operation mode.
2. The overhead ground wire based on the ground wire open tension mode and the ground wire tension insulator according to claim 1, wherein the connection mode of the ground wire jumper wire and the line tower comprises: the ground wire jumper is connected directly with the line tower or with a conventional ground wire insulator connected in parallel with the discharge gap of the ground wire.
3. The overhead ground wire based on the ground wire open tension mode and the ground wire tension insulator according to claim 1, wherein the ground wire tension insulator comprises: rod-shaped suspension composite insulator, disc-shaped suspension porcelain insulator, disc-shaped suspension glass insulator and rod-shaped suspension porcelain insulator.
4. The overhead ground wire based on the ground wire open tension mode and the ground wire tension insulator according to claim 3, wherein the connection mode of the ground wire tension insulator comprises: a single insulator type and a multiple insulator type.
5. The overhead ground wire based on the ground wire open tension mode and the ground wire tension insulator according to claim 1, wherein the line tower comprises: a tangent tower and a strain tower.
6. The overhead ground wire based on the ground wire open tension mode and the ground wire tension insulator according to claim 1 or 5, wherein the line tower is at least a two-base line tower.
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| CN201811516608.4A CN109390897B (en) | 2018-12-12 | 2018-12-12 | An overhead ground wire based on ground wire tensioning method and ground wire tension insulator |
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| CN109390897B true CN109390897B (en) | 2024-05-31 |
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