CN102709814B - Ring Parallel Gap Lightning Protection Device for Overhead Line Insulator Strings - Google Patents

Abstract

An annular parallel gap lightning protection device for an overhead line insulator string belongs to the technical field of lightning protection devices for overhead lines. The device is a pair of metal electrodes connected in parallel at two ends of an overhead line insulator string, and each metal electrode mainly comprises an annular electrode, a rod-shaped electrode, an L-shaped connecting rod and a metal clamp. The invention has the dual functions of parallel gap and equalizing ring, and the weight is light; the components are standardized, the universality is strong, and the installation is convenient; the distance between the parallel gaps is convenient to adjust, and the lightning protection device can be used for lightning protection of overhead lines with different voltage classes and has strong practicability; wide application range and the like. The invention can be widely applied to the lightning protection of overhead lines with different voltage grades in an electric power system.

Description

Ring Parallel Gap Lightning Protection Device for Overhead Line Insulator Strings

technical field

The invention belongs to the technical field of lightning protection devices for electric power overhead lines, and in particular relates to a supplementary lightning protection device for lightning protection of overhead lines.

Background technique

The lightning tripping fault of overhead lines is a difficult problem affecting the safe power supply of power grids all over the world. Today's lightning accidents still account for a large proportion of all tripping accidents on the line, especially in the southern region. According to the lightning protection operation data of Guangdong power grid lines, there were 650 lightning trips on 110kV and above lines in 2008, accounting for 62.3% of the total line trips; more than 50% of power system accidents in Japan were caused by lightning strikes on transmission lines. Lightning faults often cause line insulation damage, cause blackout accidents, cause direct economic losses to the power sector, and also have adverse effects on residents' lives and industrial and agricultural production. Therefore, enhancing the lightning protection of overhead lines is one of the important measures to ensure the safe and stable operation of the power system.

Since the line lightning tripping rate is an important indicator for assessing the safe operation of the power grid in my country, the current lightning protection measures for overhead lines in my country are mainly based on "blocking" lightning protection, that is, to improve the lightning resistance level of the line as much as possible and reduce lightning strikes. trip rate. Common lightning protection measures include erecting lightning protection wires, reducing tower grounding resistance, strengthening insulation, adding coupling ground wires, and installing line arresters, etc. Judging from decades of operating experience, "blocking" type lightning protection does play a huge role, but there is still a certain lightning trip rate and accident rate on overhead power transmission lines, which are still quite high in some areas, and lightning flashovers have caused a large number of accidents. The insulator is damaged. With the rapid development of my country's power grid in recent years, the grid structure is getting stronger and stronger, and a large number of SF6 switches, computerized relay protection and reclosing devices are widely used, and it is necessary to further develop economical, practical and efficient lightning protection devices for overhead lines. very necessary.

The "drainage" type parallel gap lightning protection device is widely used as a supplementary lightning protection protection measure for overhead lines because of its three functions of lightning discharge, transfer and dredge power frequency arc, and uniform power frequency electric field to enhance overhead power transmission Line lightning protection. The parallel gap lightning protection device of the existing overhead line insulator strings, such as the patent of "Overhead Line Parallel Gap Lightning Protection Device" published on March 23, 2005 with the announcement number CN2687923Y, the disclosed parallel gap lightning protection device, It is a pair of metal electrodes connected in parallel at both ends of the overhead line insulator string (that is, the ground side electrode and the wire side electrode). When used for 110kV overhead lines, the outer end of the wire side electrodes is spherical; when used for 220kV overhead lines, the wire The outer ends of the side electrodes are bifurcated electrodes. The main disadvantages of this device are: ① There are many types of components in the parallel gap lightning protection device, which is not conducive to standardized production; ② The parallel gap lightning protection device only considers the functions of parallel gap lightning discharge and dredging power frequency arc Only suitable for lightning protection of 110kV and 220kV overhead lines.

Contents of the invention

The object of the invention is to provide a ring-shaped parallel gap lightning protection device for overhead line insulator strings in view of the shortcomings of the existing overhead line insulator series-parallel gap lightning protection device. The "drainage" type lightning protection device has the characteristics of simple structure, standardized components, convenient mass production, convenient installation, and is suitable for high-voltage overhead lines.

The technical solution for realizing the purpose of the present invention is: a ring-shaped parallel gap lightning protection device for overhead line insulator strings, which is a pair of metal electrodes connected in parallel at both ends of the insulator strings for overhead lines. It is characterized in that: one metal electrode of the pair of metal electrodes is mainly composed of a ring electrode, a rod-shaped electrode, an "L"-shaped connecting rod and a metal clamp.

The ring electrode, the rod electrode and the "L"-shaped connecting rod are all carbon steel metal rods with a diameter of 15-20 mm.

The ring electrode is an open ring of a metal rod with an inner diameter of 300-400 mm. Weld one of the "L"-shaped connecting rods on one side of the opening of the ring electrode opening, so that the ring-shaped parallel electrode is fixedly connected to the end of the metal piece at one end of the overhead line insulator string, and the opening The ring-shaped ring electrode is used to uniform the electric field distribution near the metal parts of the overhead line insulator string and prevent the metal parts from generating corona. On the other side of the opening of the ring electrode opening, a rod-shaped electrode is fixed through a metal clamp (that is, a buckle), so as to adjust the distance between the rod-shaped electrode and the ring electrode. The included angle is used to adjust the spacing between the series and parallel gaps of overhead line insulators (that is, the short-circuit distance of lightning discharge), which is used for lightning discharge.

The rod-shaped electrode is a metal rod with a spherical end and a length of 200-400mm. The spherical diameter of one end of the rod-shaped electrode is 40-50mm to withstand the burning of a high-current arc.

The vertical rod length of the "L"-shaped connecting rod is 10mm-50mm, and the horizontal rod length is 300mm-400mm. The end of the vertical rod of the "L"-shaped connecting rod is welded on one side of the opening of the ring electrode, and the end of the horizontal rod of the "L"-shaped connecting rod is passed through a metal clamp (that is, a diamond buckle), The screws and nuts are fixedly connected to the metal piece at one end of the insulator string of the overhead line, and are used for fixing a metal electrode composed of the ring electrode and the rod-shaped electrode to one end of the insulator string of the overhead line.

The pair of metal electrodes are symmetrically connected to the two insulator strings of the overhead line through a horizontal bar of the "L"-shaped connecting bar of the ring electrode, a metal clamp (rhombic buckle), screws and nuts, respectively. The distance between the spherical ends of a pair of rod-shaped electrodes of a pair of metal electrodes is 750mm~3780mm.

After the present invention adopts above-mentioned technical scheme, mainly have following effect:

1) The ring structure of the present invention can well improve the electric field distribution at the end of the insulator string. Compared with the existing rod-shaped parallel gap, the ring-shaped parallel gap structure of the present invention has a better ability to uniform the electric field at the end of the insulator string, prevent corona from the fittings, and effectively protect the insulator string of the line.

2) Each metal electrode in the ring-shaped parallel gap of the present invention is composed of a ring electrode and a rod-shaped electrode, which not only has the function of connecting the lightning discharge point in the parallel gap, but also plays the role of "draining" the arc, and has a uniform insulator string The ability of the electric field at the end also reduces the overall load of the insulator string, which has strong practicability and a wide range of applications;

3) The rod-shaped structure of the present invention adjusts the angle between the rod-shaped electrode and the ring electrode through a metal fixture (that is, a buckle) to adjust the spacing of the parallel gap, and is fixed by the buckle, making the invention easy to install and suitable for Lightning protection for overhead lines with different voltage levels;

4) The component design is standardized, the manufacture is convenient, and the versatility is strong.

The invention can be widely applied to the lightning protection of overhead lines with different voltage levels in the power system.

Description of drawings

Fig. 1 is the structural diagram of the device of this aspect installed in the overhead line insulator string;

Fig. 2 is the top view of ring electrode in Fig. 1;

Fig. 3 is a structural diagram of connecting fittings in Fig. 1;

Fig. 4 is a volt-second characteristic curve of a 220kV overhead line insulator string;

In the figure: a volt-second characteristic curve of 220kV insulator string, b volt-second characteristic curve of insulator string installed with 1744mm circular parallel gap;

Fig. 5 Principle wiring diagram of power frequency arc burning test;

Figure 6 is a voltage distribution diagram of insulator strings for 220kV overhead lines;

In the figure, c is the electric field distribution curve of the insulator string, d is the electric field distribution curve of the insulator string installed with annular parallel gaps, and e is the electric field distribution curve of the insulator string installed with rod-shaped parallel gaps;

Fig. 7 is the electric field distribution diagram of 220kV overhead line insulator string;

In the figure, f is the insulator voltage distribution curve with annular parallel gap installed, and g is the insulator voltage distribution curve with voltage equalizing ring installed

In the figure: 1 insulator string, 2 ring electrode, 3 rod electrode, 4 metal fixture, 5 "L" shaped connecting rod, 6 nut, 7 screw, 8 fuse for simulating arc, 9 insulator string for arc burning test, 10 analog wires, 11 test power supply, 12 knife switch, 13 switch.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention:

Example 1

As shown in Figures 1 to 3, a ring-shaped parallel gap lightning protection device for 110kV overhead line insulator strings is a pair of metal electrodes connected in parallel at both ends of the insulator string 1 of the overhead line. It is characterized in that: one metal electrode in the pair of metal electrodes is mainly composed of a ring electrode 2, a rod-shaped electrode 3, an "L"-shaped connecting rod 5 and a metal clamp 4 and the like.

The ring electrode 2, the rod-shaped electrode 3 and the "L"-shaped connecting rod 5 are all carbon steel metal rods with a diameter of 15mm.

The ring electrode 2 is an open ring of a metal rod with an inner diameter of 300 mm. Weld one of the "L"-shaped connecting rods 5 on one end face of the opening of the ring electrode 2 opening, so that the ring-shaped parallel electrode is fixedly connected to the end of the metal piece at one end of the overhead line insulator string The ring electrode 2 with an open circular ring is used to evenly distribute the electric field near the metal parts of the overhead transmission line insulator string 1 and prevent the metal parts from generating corona. On the other end face of the opening of the ring electrode 2 in the open ring shape, a rod-shaped electrode is fixed through a metal clamp (that is, a buckle), so as to adjust the rod-shaped electrode 3 and the ring electrode 2 The angle between them is used to adjust the distance between the parallel gaps of the insulator strings 1 of the overhead line (that is, the short-circuit distance of lightning discharge), which is used for lightning discharge.

The rod-shaped electrode 3 is a metal rod with a spherical length of 200 mm at one end, and a spherical diameter at one end of the rod-shaped electrode 3 is 40 mm to withstand the burning of a high-current arc.

The vertical rod length of the "L" shaped connecting rod 5 is 10mm, and the horizontal rod length is 300mm. The vertical rod end of the "L"-shaped connecting rod 5 is welded on one end face of the opening of the ring electrode 2, and the horizontal rod end of the "L"-shaped connecting rod is passed through the metal clamp 4 (that is, a diamond clamp) Buckle) and screws and nuts are fixed on the metal piece at one end of the overhead transmission line insulator string 1, so as to fix a metal electrode composed of the ring electrode 2 and the rod electrode 3 to the insulator of the overhead line at one end of string 1.

The pair of metal electrodes are symmetrically connected to the insulator string of the overhead transmission line through a horizontal bar of the "L"-shaped connecting bar of the ring electrode 2, a metal clamp 4 (rhombic buckle) and screws and nuts. At both ends of 1, the distance between the spherical ends of a pair of rod-shaped electrodes 3 of a pair of metal electrodes is 750mm.

Example 2

A ring-shaped parallel gap lightning protection device for 220kV overhead line insulator strings, same as embodiment 1, wherein:

The ring electrode 2, the rod electrode 3 and the connecting rod 5 are all carbon steel metal rods with a diameter of 18 mm. The ring electrode 2 is a metal rod with an inner diameter of 350 mm. The length of the electrode 3 is 300mm, the spherical diameter of the rod-shaped electrode 3 is 45mm, the vertical rod length of the "L"-shaped connecting rod 5 is 30mm, and the horizontal rod length is 350mm.

The distance between the spherical ends of the rod-shaped electrodes 3 in the parallel gap is 1744mm.

Example 3

A ring-shaped parallel gap lightning protection device for 220kV overhead line insulator strings, same as embodiment 1, wherein:

The ring electrode 2, the rod electrode 3 and the connecting rod 5 are all carbon steel metal rods with a diameter of 20 mm. The ring electrode 2 is a metal rod with an inner diameter of 400 mm. The length of the electrode 3 is 400mm, the spherical diameter of the rod-shaped electrode 3 is 50mm, the vertical rod length of the "L"-shaped connecting rod 5 is 50mm, and the horizontal rod length is 400mm.

The distance between the spherical ends of the rod-shaped electrodes 3 in the parallel gap is 3780mm.

test results

With the overhead line annular parallel gap lightning protection device of embodiment 2, carry out following test:

1) 50% lightning impulse discharge test

This test is to check whether the lightning impulse discharge occurs between the ends of the parallel gap after the ring-shaped parallel gap is installed at both ends of the insulator string, and whether the power frequency arc path can be effectively located.

Through the test observation, the lightning wave flashover path is basically positioned at the end of the parallel gap test product, and there is a good linear relationship between the gap distance and the discharge voltage value; the lightning trip rate obtained through the calculation of the test data meets the engineering requirements.

2) Lightning impulse volt-second characteristic test

The purpose is to study the influence of the steepness change of the lightning shock wave on the flashover voltage and discharge time of the annular parallel gap. According to the principle of insulation coordination between the insulator string and the annular parallel gap, it can be seen from the lightning impulse characteristic test that the parallel gap has a good protective effect on the insulator string, as shown in Figure 4.

3) Operation shock flashover characteristic test

This test is to test the influence of the insulator strings on the overall insulation level of the line after the installation of the parallel gap. The overall insulation level meets the requirements of line insulation. The maximum operating impulse overvoltage of the 220kV line is 620kV. According to the test results, it can be seen that the annular parallel gap samples in this paper all meet the requirements of line insulation.

4) Test of arcing characteristics of power frequency arc

This test is to verify whether the arc root of the power frequency freewheeling arc after a lightning flashover can drift to the end of the parallel gap far away from the insulator string to burn, that is, the arc guiding and arc striking ability of the parallel gap and the ability to protect the insulator string from burns Effect.

See Figure 5 for the layout of the power frequency arc burning characteristic test. The short-circuit current of the low-current arcing test is 1kA, and the duration is 0.5s; due to the limitation of equipment, the amplitude of the short-circuit current of the high-current arcing test is 17.75kA, and the duration is 0.2s.

The process of the test arc movement was recorded with a high-speed camera at the test site. The results show that the arc root moves away from the insulator string at a faster speed after the parallel gap is installed, which can effectively protect the insulator string from power frequency arc burning.

5) Voltage distribution and electric field calculation of overhead lines with parallel gaps

In order to study the influence of annular parallel gaps on the voltage and electric field distribution of overhead line insulator strings, highlight the superiority of annular parallel gaps compared to bar-shaped parallel gaps, and demonstrate the feasibility of replacing grading rings with annular parallel gaps, this paper is for the installation of various fittings The insulator strings are carefully calculated.

The electric field distribution diagrams of 220kV line insulator strings installed with three different protective fittings are shown in Figure 6 and Figure 7. The maximum value of the axial electric field of the insulator with annular gap is 3.006kV/cm, which is smaller than that of the insulator with equalizing ring. The maximum electric field is 3.264kV/cm. According to the test results, it can be seen that the pressure equalization performance of the annular parallel gap even exceeds the pressure equalization effect of the general pressure equalizing ring, and greatly exceeds the pressure equalization performance of the rod parallel gap, indicating that the annular parallel gap not only has good lightning protection performance, but also It has the function of uniform and shielding electric field, and can even replace the function of the voltage equalizing ring for the insulator string.

According to the test analysis, the present invention realizes the three functions of lightning discharge, transfer and dredge power frequency arc, and uniform power frequency electric field, and realizes the voltage equalization effect on the power frequency electric field of insulator strings; it has good lightning protection protection for overhead lines and is Meet the insulation requirements of the line.

Claims (1)

1. the annular parallel connection gaps lightning protection device of an overhead transmission line insulator string; it is the two ends pair of metal electrodes in parallel of the insulator string (1) at overhead transmission line; described each metal electrode is mainly by an annular electrode (2); a clavate electrode (3); " L " shape connects rod (5) and metal fixture (4) composition; the material that described annular electrode (2) and clavate electrode (3) and " L " shape connect rod (5) is the carbon steel metal bar; described metal fixture (4); be the two ends of rhombus buckle and screw and the nut insulator string (1) that is fixed on overhead transmission line symmetrically, it is characterized in that:

The diameter that described annular electrode (2) and clavate electrode (3) and " L " shape connect rod (5) is 15 ~ 20mm;

Described annular electrode (2) is the metal bar opening annulus of internal diameter 300 ~ 400mm, on annular electrode (2) opening part one side end face of open circles annular, weld one described " L " shape and connect rod (5), on the opposite side end face of annular electrode (2) opening part of open circles annular, pass through metal fixture, be buckle, an affixed described clavate electrode (3);

Described clavate electrode (3) is that end length spherical in shape is the metal bar of 200 ~ 400mm, and the spherical diameter of described clavate electrode (3) one ends is 40 ~ 50mm;

The long 10mm ~ 50mm of being of vertical bars, horizon bar length that described " L " shape connects rod (5) are 300mm ~ 400mm, the vertical bars termination that described " L " shape connects rod (5) is welded on the side end face of described annular electrode (2) opening part, described " L " shape connects the horizon bar termination of rod (5) by metal fixture (4), be the rhombus buckle, screw and nut are fixed on the metalwork of insulator string one end of overhead transmission line;

Described pair of metal electrodes, " L " shape by a described annular electrode (2) connects the horizon bar of rod (5) and the two ends of the insulator string (1) that metal fixture (4) is fixed in overhead transmission line respectively, and the spacing of a pair of clavate electrode (3) spheric end of described pair of metal electrodes is 750mm ~ 3780mm.

Images