CN101202431A - Insulation tower head for overhead lines of distribution network - Google Patents

Abstract

The invention discloses an insulating tower head for overhead lines of a distribution network, and relates to the field of lightning overvoltage protection for overhead lines of a distribution network, wherein the insulating tower head includes insulating pillars for single-circuit or multi-circuit lines on the same pole, and the insulating tower head It also includes cross-arm insulators or cross-arm and pin/post insulators, where the overhead conductor is fixed to one end of the cross-arm insulator, or to the pin/post insulator at the end of the cross-arm, and the lowermost cross-arm insulator The other end or the middle part of the cross arm is fixed to the upper end of the insulating support, and the lower end of the insulating support is fixed to the top of the pole. According to the actual requirements of the system, insulating pillars, composite/porcelain cross-arm insulators, insulating/metal cross-arms and pin-type or post-type insulators can be used in combination to form a variety of structural types of insulation towers, which can greatly improve the insulation level of the line. Effectively prevent accidents such as line tripping, insulator damage, and insulated conductor disconnection caused by lightning-induced overvoltage on overhead lines.

Description

Insulation tower head for overhead lines of distribution network

technical field

The invention relates to the field of lightning overvoltage protection for overhead lines of a distribution network, and more particularly relates to an insulating tower head for an overhead line of a distribution network.

Background technique

The vertical distance between the conductor of the overhead line of the distribution network and the ground is relatively low, and the lightning protection is mainly based on the induction lightning. For overhead bare conductor lines, after the lightning overvoltage causes insulator flashover, the continuous power frequency freewheeling arc will often ablate the glaze layer on the surface of the insulator, which may cause the umbrella group to burst in severe cases; for overhead insulated conductor lines, lightning overvoltage will cause conductor After the insulating layer and the insulator break down and flashover, the arc root of the continuous power frequency freewheeling arc is subjected to the anti-coagulation effect of the insulating layer, and burns at the breakdown point fixed on the insulated wire, and the insulated wire will be burned soon.

At present, the lightning protection measures that have been adopted for the overhead lines of the distribution network mainly include the installation of lightning conductors, protective gaps and lightning arresters. Through the electromagnetic shielding effect, the lightning conductor can reduce the amplitude of the induced overvoltage on the conductor and reduce the number of lightning flashovers on the line, but the effect is not obvious. The protection gap uses special fittings to limit the lightning impact discharge path, and guides the arc root of the power-frequency freewheeling arc to leave the wire and burn on the fittings, and the fittings can withstand a certain energy and times of power-frequency arc burning, so as to effectively protect the insulator or insulated wire from damage. Damaged by lightning. The protection gap improves the probability of successful line reclosing, but the disadvantage is that it does not have the ability to extinguish the arc. The lightning arrester utilizes the non-linear characteristics of metal oxide resistors to absorb lightning energy, suppress power-frequency continuous current arcing, protect insulators or insulated wires from lightning damage, and at the same time prevent lightning tripping of lines. It is an ideal lightning protection measure , the disadvantage is that the cost is high, and regular maintenance is required during operation.

Starting from the perspective of improving the line insulation level, it will be of great practical significance and broad application prospects to develop a protective measure that can withstand the lightning-induced overvoltage of the overhead line and prevent the occurrence of lightning strike accidents on the overhead line of the distribution network.

Contents of the invention

Most of the poles used in the overhead lines of the distribution network are cement poles or metal poles (hereinafter collectively referred to as poles). There are two types of existing tower heads, one is to fix the cross-arm insulator on the top of the pole, and the cross-arm insulator itself The other is to fix the metal cross-arm and vertical pole through the hoop on the top of the pole, and install pin-type/column-type conventional insulators at the ends of the cross-arm and vertical pole to fix the wires. The cross arm, the vertical pole and the insulator integrally constitute the tower head. The insulation of the bare wire to the ground is the insulation of the insulator, and the insulation of the insulated wire to the ground is the insulation of the insulator plus the insulation of the wire insulation layer.

According to one aspect of the present invention, an insulating tower head for overhead lines in distribution networks is provided, including cross-arm insulators for single-circuit or multi-circuit lines on the same pole, wherein the overhead wires are fixed at one end of the cross-arm insulators, and the characteristics are as follows: The insulating tower head also includes an insulating support, wherein the other end of the lowermost cross-arm insulator is fixed to the upper end of the insulating support, and the lower end of the insulating support is fixed to the top of the pole.

According to another aspect of the present invention, there is provided an insulating tower head for overhead lines in distribution networks, including cross arms for single-circuit or multi-circuit lines on the same pole, conventional insulators and vertical poles, wherein the overhead wires are fixed on conventional insulators, and The feature is that the insulating tower head also includes an insulating support, the lower end of the stand and the middle of the lowermost cross arm are both fixed to the upper end of the insulating support, and the lower end of the insulating support is fixed to the top of the pole.

The present invention starts from the perspective of improving the insulation level of the line, and additionally installs insulating pillars on the upper end of the pole. The upper end of the insulating pillars is installed with cross-arm insulators in different ways, or insulating/metal cross-arms, vertical poles, insulating pillars and cross-arm insulators, Combining cross arm, vertical arm and insulator, an insulating tower head for overhead lines of distribution network is proposed, which can greatly improve the line insulation level.

The simulation research shows that the maximum lightning-induced overvoltage amplitude generated on the overhead lines of the distribution network generally does not exceed 400-500kV. The use of insulating tower heads can make the lines withstand the maximum lightning-induced overvoltage and prevent the overhead lines from being overvoltage due to lightning induction. Accidents such as line tripping, insulator damage, and insulated wire disconnection caused by voltage action.

Innovation point of the present invention:

(1) The present invention sets up insulating pillars on poles and towers, which are used in combination with cross-arm insulators or insulating/metal cross-arms, and conventional insulators to greatly improve the line insulation level, effectively withstand the lightning-induced overvoltage that occurs on the line, and then greatly improve Line lightning resistance level. It effectively prevents the occurrence of accidents such as line tripping, insulator damage, and insulated wire disconnection caused by lightning-induced overvoltage, so that induced lightning protection is no longer the main problem of lightning protection for distribution networks.

(2) The structure of the present invention is simple, easy to install, and the cost is slightly higher than that of the existing tower head. Compared with the use of lightning conductors, protection gaps and arresters, the cost is equivalent, but the protection effect is better, and the operation does not require maintenance.

Description of drawings

Fig. 1 a is the structure schematic diagram of the insulation tower head of the distribution network 6kV, 10kV and 20kV single-circuit line according to the insulating support of the present invention plus composite/porcelain cross-arm insulator type;

Fig. 1 b is the structure schematic diagram of the insulation tower head of the distribution network 6kV, 10kV and 20kV single-circuit lines according to the insulation support of the present invention plus insulation/metal cross-arm type;

Fig. 2a-2c is three kinds of connection modes of insulation tower head and electric pole according to the present invention;

Fig. 3 a is the structure schematic diagram of the insulating tower head of the 6kV, 10kV and 20kV double-circuit lines with the same pole of the typical insulating post plus composite/porcelain cross-arm insulator type of the present invention;

Fig. 3 b is the structure schematic diagram of the insulating tower head of the 6kV, 10kV and 20kV double-circuit lines with the same pole of the typical insulating support plus insulating/metal cross-arm type of the present invention;

Fig. 4 is the structural representation of the insulation tower head of 6kV, 10kV and 20kV same pole three-circuit line of the present invention; And

Fig. 5 is a structural schematic diagram of the insulating tower head for 6kV, 10kV and 20kV six-circuit lines on the same pole of the present invention.

Detailed ways

The specific implementation of the insulating tower head for the overhead line of the distribution network of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the same or similar reference numerals represent the same or similar components.

First of all, take the insulating tower head for 6kV, 10kV and 20kV single circuit lines as an example to make a specific description. The schematic diagrams of the structures are shown in Figures 1a and 1b. The tower head is divided into two types, namely, composite/porcelain cross-arm insulator type and insulating/metal cross-arm type.

Figure 1a shows the insulation tower head for distribution network 6kV, 10kV and 20kV single-circuit lines in the form of insulating pillars plus composite/porcelain cross-arm insulators, which mainly includes insulating pillars 3 and composite/porcelain cross-arm insulators 2, and umbrella groups are used. The composite/porcelain cross-arm insulator 2 is used as a cross-arm and a vertical pole, and the overhead conductor 1 is directly fixed on one end of the composite/porcelain cross-arm insulator 2, and the other end of the composite/porcelain cross-arm insulator 2 is fixed to the insulating support through a flange 3, and the lower end of the insulating support 3 is fixed to the pole top (not shown).

Figure 1b is an insulating tower head for 6kV, 10kV and 20kV single-circuit lines of the distribution network in the form of insulating pillars plus insulating/metal crossarms, which mainly includes insulating pillars 3, insulating/metal crossarms 4, insulating/metal vertical poles 6 and Conventional insulators 5. The overhead wire 1 is directly fixed on one end of the conventional insulator 5, and the other end of the conventional insulator 5 is respectively fixed to the two ends of the insulating/metal cross-arm 4 and the upper end of the insulating/metal vertical pole 6, and the upper end of the insulating/metal vertical pole 6 Both the lower end and the middle part of the insulating/metal cross-arm 4 are fixed to the upper end of the insulating support 3, and the lower end of the insulating support 3 is fixed to the pole top (not shown in the figure).

Wherein the insulating pillar 3 can be a porcelain pillar or a composite material pillar.

Among them, high-strength, corrosion-resistant, aging-resistant composite insulating materials or metal materials can be used as cross arms and vertical arms, and conventional insulators are installed at the ends to fix the wires.

In order to avoid the breakdown and flashover of wire phases caused by partial direct lightning strikes, a three-phase unbalanced insulation method can be adopted, that is, under the premise that the three-phase-to-ground insulation can effectively withstand lightning-induced overvoltage, the insulation level of the phase-to-ground in the setting is lower than that of the side phases .

In addition, according to the present invention, there are three ways to connect the insulating tower head and the pole, namely, a. metal flange and hoop type; b. cylindrical metal flange type; See Figures 2a-2c.

Figure 2a is the metal flange and hoop type, which is directly fastened to the top of the pole 8 through the metal flange and hoop 7; Figure 2b is the cylindrical metal flange type, using cylindrical metal flange 9, flange 9 One end of the pole and the insulating support 3 are pressure-injected into one body, and the end of the pole 8 penetrates into the other end of the cylindrical flange 9 and is sealed with an adhesive material; The lower end of the utility model is designed as an indented cylindrical cavity, and the electric pole 8 is directly inserted and poured into one body.

The specific structure of the insulating tower head for single-circuit lines according to the present invention has been described above. The design idea and method of insulating tower heads for multi-circuit lines on the same pole are the same as those for single-circuit lines, and both use insulating pillars plus composite/porcelain cross-arm insulators. , or insulating post plus insulating/metal cross arm, vertical pole and conventional insulator type, can be used in combination according to the actual situation to determine the realization type.

Considering that the multi-circuit line on the same pole is subjected to wind load and the weight of the wire is large, the structure of a single insulating support may be difficult to meet the force requirements, and the parallel structure of multiple insulating supports can be flexibly adopted, and the insulating support is fixed by the upper and lower metal flanges. One. In actual application, the wind load and wire weight should be calculated according to the number of circuit loops, and sufficient margin should be left to select the radial diameter of the insulating support and the number of parallel connections. The recommended number of parallel connections is within the range of 1 to 9.

The typical structural diagrams of insulating tower heads for multi-circuit lines on the same pole are shown in Figure 3, Figure 4 and Figure 5, where Figure 3a shows the 6kV, 10kV and 20kV double-circuit lines on the same pole in the form of insulating pillars plus composite/porcelain cross-arm insulators Figure 3b shows insulating tower heads for 6kV, 10kV and 20kV double-circuit lines on the same pole in the form of insulating pillars plus insulating/metal cross-arms, and Figure 4 and Figure 5 respectively show 6kV, 10kV and 20kV Insulating tower heads for three-circuit lines on poles and insulating tower heads for six-circuit lines on the same pole.

Referring to Fig. 3a, in the insulating tower head for double circuit lines on the same pole of the type of insulating post plus composite/porcelain cross-arm insulator, the bottom composite/porcelain cross-arm insulator 2 is fixed to the upper end of the insulating post 3. Referring to Fig. 3b, in the insulating tower head for double-circuit lines on the same pole in the type of insulating support plus insulating/metal cross-arm, the lower end of the insulating/metal vertical pole 6 and the middle part of the lowermost insulating/metal cross-arm 4 are fixed to The upper end of the insulating support 3.

Figure 4 and Figure 5 respectively show the insulating tower head for the three-circuit line on the same pole and the insulating tower head for the six-circuit line on the same pole, and the parallel structure of a plurality of insulating pillars 3 is used, that is, the insulating pillar group 10 .

Since existing tower head structures for lines such as double-circuit, three-circuit and six-circuit on the same pole are well known in the art, it is not specifically described in the present invention. In addition, the parameters of the insulating tower head include mechanical performance parameters and geometric parameters. The mechanical performance parameters refer to the insulating pillars, cross-arm insulators, cross-arms, and vertical poles, which should be able to withstand the combined effect of the wind load torsion of the conductor and the self-weight pressure of the conductor without damage. The geometric parameters refer to the insulating pillars, cross-arm insulators, crossarms, and vertical poles. The total ground-to-ground insulation distance after the combination of conventional insulators and conventional insulators should meet the requirements for withstanding lightning-induced overvoltage of the line under the premise of meeting the power frequency voltage requirements of the system. The existing tower head design method and technical conditions are determined.

Although the present invention has been specifically described above, those skilled in the art may also modify some of the above specific structures or conceive other equivalent processes to realize the present invention. Therefore, the present invention is not specifically limited to the specific process of the above-mentioned embodiment. For example, although only 6kV, 10kV and 20kV voltage levels of the distribution network are described in the description, of course, the present invention can be applied to tower heads of other power distribution system voltage levels , as long as the insulating support is added to the bottom of the common tower head structure, so that the insulation height of the wire to the ground is increased, a similar technical effect can be produced; and for example, although only double-circuit, three-circuit and For the six-circuit circuit, of course, other multi-circuit circuits on the same pole can also be conceived by those skilled in the art.

Although the present invention has been described, the above description is for the purpose of illustration only, and the present invention is not limited to the above specific description in conjunction with the accompanying drawings. Those skilled in the art can make various changes without departing from the spirit of the present invention, and the protection scope of the present invention is defined by the appended claims.

Claims (10)

1. An insulating tower head for an overhead line of a distribution network, comprising a cross-arm insulator (2) for single-circuit or multiple-circuit lines on the same pole, wherein the overhead wire (1) is fixed on one end of the cross-arm insulator (2), and its Features: The insulating tower head also includes an insulating support (3), wherein the other end of the lowermost cross-arm insulator (2) is fixed to the upper end of the insulating support (3), and the lower end of the insulating support (3) is fixed to the pole (8) top. 2. The insulating tower head according to claim 1, wherein the cross-arm insulator (2) is a composite/porcelain cross-arm insulator. 3. An insulating tower head for overhead lines in a distribution network, comprising a crossarm (4), a conventional insulator (5) and a vertical pole (6) for single-circuit or multiple-circuit lines on the same pole, wherein the overhead wire (1) is fixed on On the conventional insulator (5), it is characterized in that: The insulating tower head also includes an insulating support (3), the lower end of the vertical pole (6) and the middle part of the lowermost cross arm (4) are all fixed to the upper end of the insulating support (3), and the insulating support ( 3) The lower end is fixed to the top of the pole (8). 4. The insulating tower head according to claim 3, wherein the cross arm (4) is a composite insulation/metal cross arm, and the vertical pole (6) is a composite insulation/metal vertical pole. 5. The insulating tower head according to claim 1 or 3, wherein a parallel structure of insulating pillars (3) is used. 6. The insulation tower head according to claim 5, wherein the number of parallel connections of the insulation pillars (3) ranges from 1 to 9. 7. The insulating tower head according to claim 1 or 3, wherein the insulating support (3) is fastened to the pole (8) through a flange and a hoop (7). 8. The insulating tower head according to claim 1 or 3, wherein the insulating support (3) is integrated with one end of the flange (9), and the pole (8) penetrates into the flange (9) inside of the other end and sealed with bonding material. 9. The insulating tower head according to claim 1 or 3, wherein the lower end of the insulating pillar (3) is designed as a recessed cavity, and the pole (8) is directly inserted and poured into one body. 10. The insulating tower head according to claim 1 or 3, wherein the insulating support (3) adopts porcelain support or composite material support.

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