CN201243186Y - Parallel connection clearance device for V-shaped insulator string of high-tension overhead line - Google Patents

Abstract

The utility model provides a parallel gap device for a V-shaped insulator string of a high-voltage overhead line, which is located between insulators connected in series, and the shape of the parallel gap device is an arc angle shape. The thermal stability of the parallel gap device is good.

Description

Parallel gap device for V-shaped insulator strings for high-voltage overhead lines

technical field

The utility model relates to the field of electric power, in particular to a V-shaped insulator string and a parallel gap device for high-voltage overhead lines.

Background technique

Lightning protection and anti-pollution of overhead power transmission lines has always been a subject of research by electric power workers. In recent years, lightning faults and pollution faults are still one of the main factors affecting the safe operation of lines. Power frequency freewheeling after lightning flashover or pollution flashover will damage the insulators, causing zero-value insulators or even insulators falling out of series and power outages, which will bring difficulties to line operation and maintenance.

The existing lightning protection measures for overhead power transmission lines include: erecting lightning protection lines, reducing the grounding resistance of towers, strengthening insulation, adding coupling ground wires, and installing line arresters, etc. Its core idea is to improve the lightning resistance level of the line as much as possible and reduce the lightning trip rate. These lightning protection measures can be summarized as "blocking" lightning protection methods. For the actual situation of the weak grid structure and poor performance of my country's early power grid, it is appropriate to only use the "blocking" method for lightning protection. In recent years, my country's power grid has developed rapidly, and the grid structure has become stronger and stronger; and with technological progress, a large number of SF6 circuit breakers have been used in substations, relay protection has been computerized, and reclosing devices have been widely used. "Type" lightning protection method is not comprehensive enough.

The core idea of the "drainage type" lightning protection method of "parallel gap lightning protection of insulators" is to allow the line to have a certain lightning strike tripping rate. The gap device is connected in series and parallel with the insulator, and the lightning energy is released by the gap discharge to guide the power frequency arc. Although there is a lightning flashover, the reclosing can be successful without permanent failure.

The lightning protection principle of the parallel gap is as follows: connect a pair of metal electrodes in parallel at both ends of the insulator string (also known as arc striking angle/arc striking angle) to form a protective gap. Usually, the distance of the protective gap is less than the string length of the insulator string. When the overhead line is struck by lightning, a high lightning overvoltage is generated on the insulator string, but because the lightning impulse discharge voltage of the protection gap is lower than the discharge voltage of the insulator string, the protection gap discharges first. Under the action of electromotive force and thermal stress, the continuous power frequency arc is led to the end of the arc angle through the discharge channel formed by the parallel gap, and fixed at the end of the arc angle to burn, thereby protecting the insulator from arc burning.

The parallel gap lightning protection device should have three functions: guiding lightning discharge, transferring and dredging power frequency arc, and uniform power frequency electric field, which has a lot to do with the shape and size of the arc angle that makes up the parallel gap. For example, the parallel gaps in Japan often short-circuit the original insulator strings, and the Z/Z0 is mostly in the range of 75 to 85%. According to calculations, if the gap of Z/Z0 is 75%, it will cause lightning tripping of the line The rate is more than 30% higher than the regulation value, which is not applicable to my country's transmission lines.

Fig. 1 shows the outline structure (type I string) of a parallel gap lightning protection device for 110kV overhead lines in the prior art.

The "parallel gap lightning protection device for overhead lines" is mainly aimed at single strings of insulators (Type I strings). It is mainly composed of upper and lower electrodes. The electrode material is Q235 carbon steel, and the diameter of the steel rod is between 13 and 19mm. The upper electrode is connected to the ball joint ring on the ground side of the insulator series. In order to avoid the relative movement between the upper electrode and the ball joint ring, the cross section of the middle part of the ball joint ring is designed as a rhombus, and the connection end of the upper electrode is also designed as a corresponding shape, as shown in Figure 2 and Figure 3. The end of the upper electrode away from the insulator string is slightly upturned, which is called needle shape. The shape of the end of the lower electrode varies with the voltage level. The 110kV lower electrode is designed to be spherical. The end of the 220kV lower electrode is divided into two forks, called PS type.

The shortcoming of above-mentioned technical scheme is as follows:

(1) The parallel gap applicable to the "V" shaped insulator string is not considered

A large number of tests and theoretical calculations of the "parallel gap lightning protection device for overhead lines" are aimed at a single string of insulators (Type I) with parallel gaps. "V" shaped insulator series with parallel gap needs to be re-tested. The V-shaped insulator string is shown in Figure 4.

(2) The thermal stability requirements of the insulator parallel gap at power frequency freewheeling are not considered

With the continuous development of the urban network, the short-circuit current of the 220kV system is getting larger and larger, and the calculated value of the three-phase short-circuit current has exceeded 50kA; while the short-circuit current of the 110kV system has also reached more than 30kA, and the relay protection of some 110kV lines The disconnection time is longer. This puts forward a higher thermal stability performance requirement for the insulator parallel gap in the continuous flow of the lightning operation frequency.

Contents of the invention

The utility model aims to provide a parallel gap device for V-shaped insulator strings of high-voltage overhead lines, which can solve the above thermal stability problem.

In the embodiment of the present utility model, it is provided that the utility model provides a parallel gap device for a V-shaped insulator string of a high-voltage overhead line, which is located between insulators connected in series, and the shape of the parallel gap device is arc striking Angular shape.

Preferably, the high-voltage overhead line is 220kV, the V-shaped insulator string is 2×16 insulators, and the geometric dimensions of the arcing angle are: Z ₀ =146×16mm; Z=146×14mm; X _C =490mm; X _P = 570 mm; Y _C =219 mm; Y _P =73 mm; Z/Z ₀ =0.875.

Preferably, the high-voltage overhead line is 110kV, the V-shaped insulator string is 2×9 insulators, and the geometric dimensions of the arcing angle are: Z ₀ =146×9mm; Z=146×7.5mm; X _C =400mm; X _P =450 mm; Y _C =146 mm; Y _P =73 mm; Z/Z ₀ =0.833.

Preferably, the upward arcing angle of the arcing angle profile is a pin-shaped end upturned.

Preferably, the high-voltage overhead line is 110kV, and the end of the lower striking arc angle is spherical.

Preferably, the diameter of the spherical shape is 30-50 mm.

Preferably, the high-voltage overhead line is 220kV, and the end of the lower striking arc angle of the striking arc angle shape is an ellipse with a notch.

Preferably, the notched ellipse begins to bifurcate at 1/3 of the total length of the lower arc angle, the angle between the two bifurcations is less than or equal to 45°, and a gap of 25-35 mm is left at the end.

The thermal stability of the parallel gap device is good.

Description of drawings

The drawings described here are used to provide a further understanding of the utility model and constitute a part of the application. The schematic embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute improper limitations to the utility model. In the attached picture:

Fig. 1 shows the outline structure (I-type string) of the 110kV overhead line parallel gap lightning protection device in the prior art;

Figure 2 shows the appearance of the arcing angle on the insulator parallel gap in Figure 1;

Fig. 3 shows the external view of the ball hanging ring in Fig. 1;

Figure 4 shows an assembly diagram of a V-shaped insulator string;

Fig. 5 shows the appearance diagram of the arcing angle on the series-parallel gap of the V-shaped insulator according to the embodiment of the present invention;

Fig. 6 shows the appearance diagram of the arc angle under the series-parallel gap of the V-shaped insulator of the 110kV line according to the embodiment of the present invention;

Fig. 7 shows the appearance diagram of the arc angle under the series-parallel gap of the V-shaped insulator of the 220kV line according to the embodiment of the present invention;

Fig. 8 shows a V-type insulator series parallel gap ball joint hanging plate according to an embodiment of the present invention;

Fig. 9 shows a parallel gap bowl hanging plate for V-shaped insulator strings according to an embodiment of the present invention.

Detailed ways

The utility model will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Fig. 5 shows an outline diagram of an arc striking angle on a series-parallel gap of a V-shaped insulator according to an embodiment of the present invention, and the appearance of the parallel gap device is an arc striking angle outline.

The arc angle shape design of the parallel gap is smooth, without small angle bending, which ensures the speed of the arc during the moving process. The arc angle is connected in series and parallel with the V-shaped insulator, so that the lightning discharges along the gap, guides the power frequency arc, and protects the insulator from burns. It is a powerful supplement to the traditional lightning protection measures for transmission lines. The V-shaped parallel gap arcing angle designed in this embodiment draws out the power frequency arc within the allowable short-circuit time, which can significantly reduce the insulator damage of the line due to lightning strike or pollution flashover.

Preferably, the high-voltage overhead line is 220kV, the V-shaped insulator string is 2×16 insulators, and the geometric dimensions of the arcing angle are: Z ₀ =146×16mm; Z=146×14mm; X _C =490mm; X _P = 570 mm; Y _C =219 mm; Y _P =73 mm; Z/Z ₀ =0.875.

Preferably, the high-voltage overhead line is 110kV, the V-shaped insulator string is 2×9 insulators, and the geometric dimensions of the arcing angle are: Z ₀ =146×9mm; Z=146×7.5mm; X _C =400mm; X _P =450 mm; Y _C =146 mm; Y _P =73 mm; Z/Z ₀ =0.833.

The following table is a list of the geometric dimensions of the arcing angle of the parallel gap

insulator string Z ₀ /mm Z/mm X _C /mm X _P /mm Y _C /mm Y _P /mm Z/Z ₀ 220kV V-string 146×16 146×14 490 570 219 73 0.875 110kV V-string 146×9 146×7.5 400 450 146 73 0.833

There is no obvious difference in lightning discharge voltage (U _50% value) and discharge path for gaps with different arc angle shapes.

Preferably, the upward arcing angle of the arcing angle profile is a pin-shaped end upturned.

The upper arc angles are all upturned with needle-shaped ends. This design makes the Z value of the parallel gap not change due to the ablation of the upper arc angle ends.

The end of the lower arc angle of the parallel gap of 110kV insulators can be spherical to increase its ability to resist arc ablation. The diameter of the ball can be 30-50mm. Fig. 6 shows the appearance of arcing angle under the series-parallel gap of V-type insulators for 110kV line according to the embodiment of the present invention. Fig. 8 shows a parallel gap ball stud hanging plate for V-shaped insulator strings according to an embodiment of the present invention.

The lower striking arc angle of the parallel gap of 220kV insulators can be designed as an ellipse with a gap (starting to bifurcate at 1/3 of the total length of the lower striking arc angle, the angle between the two bifurcations is less than or equal to 45 degrees, and 25~ 35mm gap), the gap can prevent the arc transfer speed from being too slow. Fig. 7 shows the appearance of arcing angle at the lower gap between series and parallel connection of V-type insulators for 220kV line according to the embodiment of the present invention. Fig. 9 shows a parallel gap bowl hanging plate for V-shaped insulator strings according to an embodiment of the present invention.

These two kinds of gaps can be used for 220kV 2×16 piece insulator hanging V-type string, and 110kV 2×9 piece insulator hanging V-type string. The parallel gap device is composed of upper and lower arc angles. One end of the upper striking arc angle is connected with the ball joint hanging ring on the grounding side of the insulator series. The lower striking arc angle is connected with the bowl head on the wire side of the insulator string. The arcing angle of the V-shaped series-parallel gap device is placed symmetrically along the wire.

Figures 5 to 9 show the schematic diagrams of the arcing angles of the parallel gaps used for series V-type insulators of 110kV and 220kV overhead lines. In the design of parallel gap connection fittings (ball head, bowl head), standard parts should be used as much as possible in principle, and some fittings should be specially designed according to needs. Fig. 8 and Fig. 9 are V-shaped insulator strings with parallel gap ball end hanging plate and bowl end hanging plate.

In practice, in order to ensure that the series parallel gaps of V-type insulators of 110kV and 220kV overhead lines can protect the insulators during lightning flashover or pollution flashover, lightning impulse (U _50% ) and volt-second characteristic tests and power frequency large Current arcing characteristic test. The applicant has carried out lightning impulse (U _50% ) and volt-second characteristic tests and power frequency high-current arcing characteristic tests on the invented gap device. The lightning impulse discharge voltage (U ₅₀ %) test was carried out on the parallel gap test sample.

① The lightning impulse (U _50% ) test is to study whether the lightning impulse discharge occurs in the air gap at the end of the arcing angle after the gaps at both ends of the insulator string are connected in parallel. Through the test observation, the lightning wave flashover path is at the end of the sample. There is a good linear relationship between the gap distance and the discharge voltage value.

② The volt-second characteristic test of the parallel gap is carried out, the purpose is to study the influence of the change of the lightning shock wave steepness on the flashover voltage and the discharge path of the parallel gap. From the lightning volt-second characteristic test, it can be seen that the parallel gap plays a very good role in protecting the insulator.

③ The arcing characteristic test of power frequency arc is to study whether the parallel gap can make the arc formed by power frequency continuous flow leave the insulator and develop outward along the arc angle after the insulator string with parallel gap is struck by lightning, so as to protect the insulator string . The test results of power frequency and high current arcing characteristics show that the parallel gap arc angle designed in this project can lead out the power frequency arc within the allowable short-circuit time. The parallel gap of insulators can withstand 50kA power frequency arc burning for 0.2s, and can protect the insulators from arc burning, which can significantly reduce the damage of insulators caused by lightning strikes or pollution flashovers.

The utility model is suitable for the parallel gap of V-shaped suspension insulator strings of 110kV and 220kV transmission lines, has a simple structure and can protect the insulators. The test results of power frequency and high current arcing characteristics show that the shape design with smooth arc angle is beneficial to the dredging of power frequency arc. The insulator parallel gap developed by the utility model can withstand 50kA power frequency electric arc for 0.2s and can protect the insulator from electric arc burning. For substations with large busbar short-circuit current, insulator parallel gaps are installed on several base towers at the outlet to meet the thermal stability requirements of short-circuit current. The shape and outer diameter of the existing parallel gap can ensure at least three times of 50kA power frequency current continuous arcing for 0.2s without changing the size of the gap, so that the parallel gap is still effective.

From the above description, it can be seen that the above-mentioned embodiments of the utility model have achieved the following technical effects:

(1) The developed parallel gap suitable for V-shaped suspension insulator strings of 110kV and 220kV transmission lines has a simple structure and can protect the insulators during lightning or pollution flashovers.

(2) The parallel gap of insulators developed by the utility model can withstand 50kA power frequency arc burning for 0.2s, and can protect the insulators from arc burning.

The above descriptions are only preferred embodiments of the utility model, and are not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (8)

1. A parallel gap device for V-type insulator strings of high-voltage overhead lines, which is between insulators connected in series, characterized in that, the profile of the parallel gap device is an arc angle profile. 2. The parallel gap device according to claim 1, wherein the high-voltage overhead line is 220kV, the V-shaped insulator string is 2×16 insulators, and the geometric dimensions of the arcing angle are: Z ₀ =146×16mm; Z=146×14mm; X _C = 490mm; X _P = 570mm; Y _C =219mm; Y _P = 73mm; Z/Z ₀ =0.875. 3. The parallel gap device according to claim 1, characterized in that, the high-voltage overhead line is 110kV, the V-shaped insulator string is 2×9 insulators, and the geometric dimensions of the arc angle are: Z ₀ =146×9mm; Z=146×7.5mm; X _C = 400mm; X _P = 450mm; Y _C = 146mm; Y _P = 73mm; Z/Z ₀ =0.833. 4 . The parallel gap device according to claim 1 , characterized in that, the upper arc angle of the profile of the arc angle is a pin-shaped end upturned. 5 . The parallel gap device according to claim 1 , wherein the high-voltage overhead line is 110 kV, and the end of the lower arc angle of the arc angle shape is spherical. 6 . 6. The parallel gap device according to claim 5, characterized in that, the diameter of the spherical shape is 30-50 mm. 7. The parallel gap device according to claim 1, wherein the high-voltage overhead line is 220kV, and the end of the lower arc angle of the arc angle profile is an oval shape with a notch. 8. The parallel gap device according to claim 7, characterized in that, the ellipse with a notch begins to bifurcate at 1/3 of the total length of the lower striking arc angle, and the angle between the two bifurcations is less than or equal to 45°, leaving a gap of 25-35mm at the end.

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