阅读说明：本技术 一种架空输电线路用y型双间隙防雷装置 (Y-shaped double-gap lightning protection device for overhead transmission line ) 是由 王成 黄福勇 岳一石 龚政雄 邹妍晖 王海跃 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种架空输电线路用Y型双间隙防雷装置,包括：限压器、原始绝缘子串以及新增绝缘子串；所述限压器底端的电极与新增绝缘子串的顶端钢帽通过电导线相连,所述新增绝缘子串连接于原始绝缘子串的末端钢脚,且新增绝缘子串的末端设有放电电极；所述新增绝缘子串的顶端钢帽与放电电极之间形成新增绝缘子串间隙；该方案中的放电电极采用双间隙结构设计,空气间隙与并联的绝缘子串间隙形成一体式并联双间隙结构,根据电压等级确定绝缘子串间隙后空气间隙距离可精确控制,当输电线路导线存在雷电过电压时双间隙结构确保沿其中一个间隙放电,双间隙形成双保险功能,避免由于间隙放电分散性导致过电压未经过限压器情况。(The invention discloses a Y-shaped double-gap lightning protection device for an overhead transmission line, which comprises: the voltage limiter, the original insulator string and the newly added insulator string; the electrode at the bottom end of the voltage limiter is connected with the top steel cap of the newly-added insulator string through an electric lead, the newly-added insulator string is connected with the tail end steel pin of the original insulator string, and the tail end of the newly-added insulator string is provided with a discharge electrode; a newly-added insulator string gap is formed between the top steel cap of the newly-added insulator string and the discharge electrode; the discharge electrode in the scheme adopts a double-gap structure design, the air gap and the parallel insulator string gap form an integrated parallel double-gap structure, the air gap distance can be accurately controlled after the insulator string gap is determined according to the voltage grade, when the lightning overvoltage exists on the wire of the power transmission line, the double-gap structure ensures that the discharge is carried out along one of the gaps, the double-gap structure forms a double-insurance function, and the condition that the overvoltage does not pass through the voltage limiter due to the gap discharge dispersity is avoided.)

1. The utility model provides a Y type double gap lightning protection device for overhead transmission line which characterized in that includes: the voltage limiter, the original insulator string and the newly added insulator string; the electrode at the bottom end of the voltage limiter is connected with the top steel cap of the newly-added insulator string through an electric lead, the newly-added insulator string is connected with the tail end steel pin of the original insulator string, and the tail end of the newly-added insulator string is provided with a discharge electrode; a newly-added insulator string gap is formed between the top steel cap of the newly-added insulator string and the discharge electrode;

the length of an air gap formed by the end part of the discharge electrode and the bottom of the voltage limiter is L, the length of the newly added insulator string gap hardware string is L0, and L/L0 is less than or equal to 0.82.

2. The Y-shaped double-gap lightning protection device for the overhead transmission line of claim 1, wherein a zinc oxide resistor disc is arranged inside the voltage limiter.

3. The Y-shaped double-gap lightning protection device for the overhead transmission line of claim 2, wherein the voltage limiter is externally provided with shed silicon rubber with different diameter sizes at intervals.

4. A Y-type double-gap lightning protection device for overhead transmission lines according to claim 3, wherein the diameters of the umbrella skirt silicone rubber arranged outside the voltage limiter are arranged according to large, small, medium, small, large and small, and the diameters of the large, medium and small umbrella skirt silicone rubber are 300mm, 240mm and 180mm, respectively.

5. The Y-shaped double-gap lightning protection device for overhead transmission lines according to claim 1, wherein the end of the discharge electrode is tilted upward at 90 ° to the bottom plate electrode of the voltage limiter.

6. A Y-type double gap lightning protection device for overhead transmission lines according to claim 1, wherein said discharge electrode is a high voltage rod-shaped electrode and is externally sheathed with an insulating sheath.

7. The Y-shaped double-gap lightning protection device for the overhead transmission line of claim 1, wherein the discharge electrode is installed on the insulator steel leg of the newly added insulator chain in a hoop manner.

8. The Y-shaped double-gap lightning protection device for the overhead transmission line according to claim 1, wherein the insulator on the newly added insulator string is a toughened glass insulator.

9. The Y-shaped double-gap lightning protection device for the overhead transmission lines of claim 1, wherein the diameter of the first insulator of the newly added insulator string is larger than the diameters of the rest insulators.

10. The Y-shaped double-gap lightning protection device for the overhead transmission line according to claim 1, wherein the relation between the power frequency operating voltage and the number of insulator pieces on the newly added insulator string is as follows: u70 × N;

wherein, U is the power frequency operating voltage, and N is the number of insulator pieces on newly-increased insulator chain.

Technical Field

The invention belongs to the field of lightning protection of power transmission lines, and particularly relates to a Y-shaped double-gap lightning protection device for an overhead power transmission line.

Background

Lightning stroke is a main cause of tripping of an overhead transmission line, and the safe and stable operation of a power grid is influenced by frequent tripping of the transmission line; the operation experience shows that installing the line arrester in the line section with strong lightning activity or high soil resistivity and difficult ground resistance reduction is an effective method for reducing the lightning trip-out rate. The lightning arrester of the line can greatly improve the lightning-resistant level of the power transmission line and reduce the lightning flashover rate of the power transmission line.

At present, line arresters are mainly composed of two types, namely with and without a series gap. Compared with the arrester without the gap, the arrester with the series gap enables the arrester body not to directly bear power frequency voltage through installing the series gap, and the aging speed of the valve block is greatly reduced compared with the arrester without the gap. Meanwhile, the lightning arrester body is not influenced by the operation overvoltage, the reference voltage of the lightning arrester body is low, and the lightning arrester body can be designed in a small size and light weight mode. Existing series gaps mainly use belt support gaps or air gaps. The total length of the serial gap supporting piece of the line arrester with the supporting piece gap and the arrester body is generally larger than that of a line insulator, the installation difficulty is higher, and accurate insulation matching calculation is required; the series gap support is a composite insulator with a short structural height, and the service life of the composite insulator is influenced by the electric field intensity born by operation and gap arcing. The gap distance of the air gap line arrester changes under the action of strong wind, so that the lightning overvoltage breakdown voltage changes, the insulation fit of the line arrester and an insulator is influenced, and the failure condition of the arrester can be caused.

Disclosure of Invention

The invention aims to solve the problems that the gap distance of the existing line arrester with the series gap is difficult to accurately control, the service life of the series support gap of a synthetic material is short, the air gap distance is influenced by strong wind and the like, and provides a Y-shaped double-gap lightning protection device for an overhead transmission line.

The technical scheme provided by the invention is as follows:

the utility model provides a Y type double gap lightning protection device for overhead transmission line, includes: the voltage limiter, the original insulator string and the newly added insulator string; the electrode at the bottom end of the voltage limiter is connected with the top steel cap of the newly-added insulator string through an electric lead, the newly-added insulator string is connected with the tail end steel pin of the original insulator string, and the tail end of the newly-added insulator string is provided with a discharge electrode; a newly-added insulator string gap is formed between the top steel cap of the newly-added insulator string and the discharge electrode;

the length of an air gap formed by the end part of the discharge electrode and the bottom of the voltage limiter is L, the length of the newly added insulator string gap hardware string is L0, and L/L0 is less than or equal to 0.82.

By adopting the Y-shaped double-gap lightning protection device, the bottom of the lightning protection device and the lead of the high-voltage side power transmission line are insulated by using the insulator string gap and the discharge electrode air gap double gaps when the line normally runs. Compared with the traditional lightning arrester using a fixed gap or a pure air gap, the equivalent capacitance of the insulator string gap between the voltage limiter and the wire of the power transmission line and the equivalent capacitance of the two gaps of the air gap of the discharge electrode are in parallel connection, and the air gap of the discharge electrode is matched with the insulator string in use.

In the scheme, the insulator string gaps are only standby gaps, and in order to avoid zero values of insulators caused by multiple discharges of the insulator string gaps, the air gaps need to be stably discharged when lightning overvoltage is generated;

when the circuit is struck by lightning, the lightning impulse breakdown voltage of the discharge electrode is less than that of the newly-added insulator string, so that when overvoltage generated at two ends of the discharge electrode exceeds the action voltage of the lightning protection device body, the voltage at two ends of the protected insulator is limited by the voltage limiter. When the air gap is in large swing under the condition of extreme strong wind to cause the failure of air gap discharge, the insulator string between the bottom of the lightning protection device and the wire of the power transmission line is discharged and punctured, and the voltage at two ends of the protected insulator is limited by the voltage limiter. The air gap of the discharge electrode and the gap of the insulator string are used as a complete accessory, and after the gap structure height of the insulator string is selected for the power transmission lines with different voltage grades, the air gap of the discharge electrode and the gap of the insulator string are integrally installed, and the gap height can be accurately controlled.

50% lightning impulse breakdown voltage U of insulator string gap length_L050％533 × L0+132, where L0 is meters and U is kilovolts, the air gap may be equivalent to a rod-plate discharge gap with a 50% lightning strike breakdown voltage U_L50％1556/(1+ 3.89/L). The invention has the difficulty that the key design point of insulation matching of the insulator string gap and the air gap is the point of how to avoid the phenomenon that the zero value of the insulator is caused by the fact that the insulator string gap is subjected to multiple discharges, and the air gap needs to be stably discharged when lightning overvoltage is generated. Therefore, the technical scheme considers U_L50％≤0.9U_L050％And obtaining the gap distance relation which needs to satisfy L ≧ (0.963+ 3.89L 0)/(2.996-L0).

Furthermore, a zinc oxide resistance card is arranged inside the voltage limiter.

Furthermore, umbrella skirt silicon rubber with different diameters is arranged outside the pressure limiter at intervals.

Furthermore, the diameters of the umbrella skirt silicon rubber arranged outside the pressure limiter are arranged according to the large, small, medium, small, large and small sizes, and the diameters of the large, medium and small umbrella skirt silicon rubber are respectively 300mm, 240mm and 180 mm.

Furthermore, the end part of the discharge electrode is tilted upwards and forms a 90-degree angle with the bottom plate electrode of the voltage limiter.

The end part of the discharge electrode is upwarped to form a rod-plate discharge gap between the end part and the bottom of the voltage limiter.

Furthermore, the discharge electrode is a high-voltage rod-shaped electrode, and an insulating sleeve is sleeved outside the discharge electrode.

Because the root of the discharge electrode generates corona and discharges to the insulator string gap, the section of the discharge electrode close to the insulator is sleeved with an insulating outer sleeve, and the section is prevented from generating discharge.

Furthermore, the discharge electrode is installed on the insulator steel foot of the newly-added insulator string in a hoop mode.

Furthermore, the insulators on the newly-added insulator strings are toughened glass insulators.

Further, the diameter of the first insulator of the newly-added insulator string is larger than the diameters of the rest insulators.

Further, the relationship between the power frequency operating voltage and the number of the insulator pieces on the newly-added insulator string is as follows: u70 × N.

Wherein, U is the power frequency operating voltage, and N is the number of insulator pieces on newly-increased insulator chain.

According to the Y-shaped double-gap lightning protection device, the air gap of the discharge electrode and the gap of the parallel insulator string form an integrated parallel double-gap structure, when the number of insulator pieces on the newly added insulator string is determined, the gap length of the insulator string can be obtained, the distance of the air gap of the discharge electrode can be accurately controlled, when a lightning overvoltage exists on a lead of a power transmission line, the double-gap structure ensures discharge along one gap, the double-gap structure forms a double-insurance function, and the condition that the overvoltage does not pass through a voltage limiter due to gap discharge dispersity is avoided. The installation process is simple, the installation cost is low, and the high reliability of the lightning protection device is ensured by the double-gap structural design.

Advantageous effects

The technical scheme of the invention provides a Y-shaped double-gap lightning protection device for an overhead transmission line, which comprises the following components: the voltage limiter, the original insulator string and the newly added insulator string; the electrode at the bottom end of the voltage limiter is connected with the top steel cap of the newly-added insulator string through an electric lead, the newly-added insulator string is connected with the tail end steel pin of the original insulator string, and the tail end of the newly-added insulator string is provided with a discharge electrode; a newly-added insulator string gap is formed between the top steel cap of the newly-added insulator string and the discharge electrode; the discharge electrode in the scheme adopts a double-gap structure design, the air gap and the parallel insulator string gap form an integrated parallel double-gap structure, the air gap distance can be accurately controlled after the insulator string gap is determined according to the voltage grade, when the lightning overvoltage exists on the wire of the power transmission line, the double-gap structure ensures that the discharge is carried out along one of the gaps, the double-gap structure forms a double-insurance function, and the condition that the overvoltage does not pass through the voltage limiter due to the gap discharge dispersity is avoided. The installation process is simple, the installation cost is low, and the high reliability of the lightning protection device is ensured by the double-gap structural design.

Drawings

Fig. 1 is a schematic structural diagram of a Y-type double-gap lightning protection device for an overhead transmission line according to an embodiment of the present invention;

wherein: 1-voltage limiter, 2-voltage limiter electrode, 3-connecting wire, 4-discharging electrode, 5-transmission line wire, 6-newly added insulator string, 7-original insulator string.

Detailed Description

The invention will be further described with reference to the following figures and examples.

As shown in fig. 1, a Y-type double-gap lightning protection device for overhead transmission lines includes: the voltage limiter, the original insulator string and the newly added insulator string; the electrode at the bottom end of the voltage limiter is connected with the top steel cap of the newly-added insulator string through an electric lead, the newly-added insulator string is connected with the tail end steel pin of the original insulator string, and the tail end of the newly-added insulator string is provided with a discharge electrode; a newly-added insulator string gap is formed between the top steel cap of the newly-added insulator string and the discharge electrode;

the length of an air gap formed by the end part of the discharge electrode and the bottom of the voltage limiter is L, the length of the newly added insulator string gap hardware string is L0, and L/L0 is less than or equal to 0.82.

The electrode at the bottom end of the voltage limiter is connected with the steel cap at the top end of the newly added insulator string through an electric lead, so that the whole body of the lightning protection device and the steel cap on the insulator at the top end of the newly added insulator string form equal potential;

in this example, the connecting wire 3 is designed by soft copper wire, one end of the connecting wire is installed at the bottom of the voltage limiter 1, the other end of the connecting wire is sleeved on the insulator steel cap at the top of the newly added insulator, the length of the connecting wire is determined according to insulation fit check and windage yaw check, and the length of the connecting wire is slightly larger than the air insulation length.

50% lightning impulse breakdown voltage U of insulator string gap length_L050％533 × L0+132, where L0 is meters and U is kilovolts, the air gap may be equivalent to a rod-plate discharge gap with a 50% lightning strike breakdown voltage U_L50％1556/(1+ 3.89/L). The invention has the difficulty that the key design point of insulation matching of the insulator string gap and the air gap is the point of how to avoid the phenomenon that the zero value of the insulator is caused by the fact that the insulator string gap is subjected to multiple discharges, and the air gap needs to be stably discharged when lightning overvoltage is generated. Therefore, the technical scheme considers U_L50％≤0.9U_L050％And obtaining the gap distance relation which needs to satisfy L ≧ (0.963+ 3.89L 0)/(2.996-L0).

And a zinc oxide resistor disc is arranged in the voltage limiter, and when the zinc oxide resistor disc bears overvoltage, the residual voltage of the lightning protection device is limited to be lower than the flashover voltage of an original insulator string 7 on a circuit through the nonlinear resistance characteristic, wherein the original insulator string is the insulator string to be protected.

Umbrella skirt silicon rubbers with different diameters are arranged outside the pressure limiter at intervals, the diameters of the umbrella skirt silicon rubbers arranged outside the pressure limiter are arranged according to the large, small, medium, small, large and small diameters, and the diameters of the large, medium and small umbrella skirt silicon rubbers are 300mm, 240mm and 180mm respectively; the effective value of power frequency voltage which can be borne by a group of large, small, medium, small, large and small umbrella skirt silicon rubbers is 20 kilovolts, and when the voltage level on a power transmission line is higher, a plurality of groups of umbrella skirt silicon rubbers are arranged; the design of different diameters of adjacent sheds can design and effectively increase the creepage distance of the shed outside the lightning protection device and the shed distance, increase the creepage distance of surface electric arcs, prevent the surface flashover caused by ice coating, bird droppings or foreign matters, and ensure that the charge transfer path of lightning overvoltage passes through the zinc oxide resistance chip.

The end part of the discharge electrode is upwards warped and forms a 90-degree angle with the bottom plate electrode of the voltage limiter, and the end part of the discharge electrode is upwards warped to form a rod-plate discharge gap with the bottom of the voltage limiter; the size of the gap is calculated, and the discharge voltage of 50% of the lightning overvoltage of the gap is smaller than the discharge voltage of about 10% of the gap of the insulator string corresponding to the newly added insulator string, so that the lightning overvoltage generates an electric arc through the discharge electrode 4 to the voltage limiter 1 to act. In order to avoid the arc generated by the discharge electrode 4 from developing to the insulator string, the electrode arranged at the bottom end of the voltage limiter 1 is an annular discharge electrode with a larger diameter, so that the arc develops to the bottom of the voltage limiter 1 through the annular discharge electrode.

The discharge electrode is a high-voltage rod-shaped electrode, and an insulating outer sleeve is sleeved outside the discharge electrode; because the root of the discharge electrode generates corona and discharges to the insulator string gap, the section of the discharge electrode close to the insulator is sleeved with an insulating outer sleeve, and the section is prevented from generating discharge.

And the discharge electrode is arranged on the insulator steel foot of the newly-added insulator string in a hoop mode.

The diameter of the first insulator of the newly-added insulator string is larger than the diameters of the rest insulators, so that ice coating flashover prevention, bird droppings or foreign matter flashover prevention and the like can be further guaranteed.

The relation between the power frequency operating voltage and the number of the insulator pieces on the newly-added insulator string is as follows: u70 × N; wherein, U is the power frequency operating voltage, and N is the number of insulator pieces on newly-increased insulator chain.

According to the Y-shaped double-gap lightning protection device, the air gap of the discharge electrode and the gap of the parallel insulator string form an integrated parallel double-gap structure, when the number of insulator pieces on the newly added insulator string is determined, the gap length of the insulator string can be obtained, the distance of the air gap of the discharge electrode can be accurately controlled, when a lightning overvoltage exists on a lead of a power transmission line, the double-gap structure ensures discharge along one gap, the double-gap structure forms a double-insurance function, and the condition that the overvoltage does not pass through a voltage limiter due to gap discharge dispersity is avoided. The installation process is simple, the installation cost is low, and the high reliability of the lightning protection device is ensured by the double-gap structural design.

The number of insulator string gaps and the dry arc distance are designed according to the voltage grade of a transmission line, and the insulator string gaps can bear the maximum power frequency overvoltage and the maximum operation overvoltage of a system, for example, for a 35 kV line, the insulator string gaps can bear the maximum 51 kV voltage. And the insulator on the newly-added insulator string is selected from glass insulators by considering the flexible adjustment of the insulator gap and the convenience in maintenance.

When the discharge gap formed by the discharge electrode 4 and the voltage limiter 1 fails to discharge under the lightning overvoltage, the lightning overvoltage enables the insulator string gap to discharge and break down, and the voltage limiter 1 acts through the connecting wire 23.

By adopting the Y-shaped double-gap lightning protection device, the bottom of the lightning protection device and the lead of the high-voltage side power transmission line are insulated by using the insulator string gap and the discharge electrode air gap double gaps when the line normally runs. Compared with the traditional lightning arrester using a fixed gap or a pure air gap, the equivalent capacitance of the insulator string gap between the voltage limiter and the wire of the power transmission line and the equivalent capacitance of the two gaps of the air gap of the discharge electrode are in parallel connection, and the air gap of the discharge electrode is matched with the insulator string in use.

In the scheme, the insulator string gaps are only standby gaps, and in order to avoid zero values of insulators caused by multiple discharges of the insulator string gaps, the air gaps need to be stably discharged when lightning overvoltage is generated;

when the circuit is struck by lightning, the lightning impulse breakdown voltage of the discharge electrode is less than that of the newly-added insulator string, so that when overvoltage generated at two ends of the discharge electrode exceeds the action voltage of the lightning protection device body, the voltage at two ends of the protected insulator is limited by the voltage limiter. When the air gap is in large swing under the condition of extreme strong wind to cause the failure of air gap discharge, the insulator string between the bottom of the lightning protection device and the wire of the power transmission line is discharged and punctured, and the voltage at two ends of the protected insulator is limited by the voltage limiter. The air gap of the discharge electrode and the gap of the insulator string are used as a complete accessory, and after the gap structure height of the insulator string is selected for the power transmission lines with different voltage grades, the air gap of the discharge electrode and the gap of the insulator string are integrally installed, and the gap height can be accurately controlled.

The foregoing is a more detailed description of embodiments of the invention and is not intended to limit the embodiments of the invention solely thereto, as will be apparent to those skilled in the art to which the invention pertains, and as such, numerous simplifications or substitutions may be made without departing from the spirit of the invention which shall be deemed to be within the scope of the invention as defined by the claims appended hereto.