阅读说明：本技术 外部间隙线路避雷器 (External gap line arrester ) 是由 H·鲁科莱宁 于 2019-09-09 设计创作，主要内容包括：本文提出的实施例涉及用于输电线路的外部间隙线路避雷器EGLA。EGLA包括具有第一端和第二端的串联变阻器单元SVU(1),该SVU被配置为连接在输电线和地之间,串联连接到SVU的第一端的主火花放电间隙单元(8),布置在SVU的第二端和地之间的辅助间隙,且辅助间隙串联连接到SVU的第二端,与辅助间隙并联连接的短路连接装置(3),以及布置在短路连接装置中的断开装置(4),该断开装置被配置为当SVU过载时断开短路连接装置。还提出了一种由EGLA执行的冲击保护方法。(Embodiments presented herein relate to an external gap line arrester EGLA for a power transmission line. The EGLA comprises a series varistor unit SVU (1) having a first end and a second end, the SVU being configured to be connected between the power line and ground, a main spark discharge gap unit (8) connected in series to the first end of the SVU, an auxiliary gap arranged between the second end of the SVU and ground, the auxiliary gap being connected in series to the second end of the SVU, a short-circuit connection device (3) connected in parallel with the auxiliary gap, and a disconnection device (4) arranged in the short-circuit connection device, the disconnection device being configured to disconnect the short-circuit connection device when the SVU is overloaded. An impact protection method performed by the EGLA is also presented.)

1. An External Gap Line Arrester (EGLA) for a power transmission line, comprising:

a series varistor unit SVU (1) having a first end and a second end, the SVU configured to be connected between a power line and ground;

a main spark discharge gap unit (8) connected in series to a first end of the SVU;

an auxiliary gap disposed between the second end of the SVU and ground, the auxiliary gap connected in series to the second end of the SVU;

a short-circuit connection device (3) connected in parallel with the auxiliary gap; and

-a disconnecting device (4) arranged in the short-circuit connection device, the disconnecting device being configured to disconnect the short-circuit connection device when the SVU is overloaded.

2. The EGLA of claim 1, wherein the main spark discharge gap cell is configured to spark discharge for lightning strikes and for switching strikes, but not for power frequency temporary over-voltage TOV.

3. The EGLA of claim 1, wherein the main spark discharge gap cell is configured to spark discharge for lightning strikes and not for power frequency temporary over-voltage TOV.

4. The EGLA of any of claims 1-3, wherein the auxiliary gap is configured to not spark out for a switching surge.

5. The EGLA of any of claims 1-3, wherein the auxiliary gap is configured to not spark discharge with the main spark discharge gap for a switching shock.

6. The EGLA of any of claims 1 to 5, wherein the disconnection means is configured to disconnect the short-circuit connection means by dividing the short-circuit connection means into two separate parts.

7. The EGLA of any one of claims 1 to 6, wherein the EGLA is sized for ultra-high pressure.

8. The EGLA of any of claims 1 to 7, wherein the short-circuit connection device is a visual fault indicator of the SVU.

9. The EGLA of any of claims 1-8, wherein the disconnect device comprises an explosive charge having a passive trigger.

10. A method for surge protection of a power transmission line, the method being performed in an external gap line arrester, EGLA, the method comprising:

when a series varistor unit SVU connected between a power transmission line and ground is overloaded (S100), spark discharge through a main spark discharge gap unit connected in series between a first terminal of the SVU and the power transmission line;

-opening (S110) a short-circuit connection device by means of a disconnection device, the short-circuit connection device being arranged in parallel with an auxiliary gap arranged in series between the second end of the SVU and ground.

11. The method of claim 10, wherein the voltage of the spark discharge is caused by a lightning strike or a switching strike rather than by a power frequency Temporary Overvoltage (TOV).

12. The method of claim 10 or 11, wherein the auxiliary gap is configured not to spark for a switching surge.

13. The method of claim 10 or 11, wherein the auxiliary gap is configured to not spark discharge with the main spark discharge gap for a switching shock.

14. A method according to any one of claims 10 to 13, wherein the disconnecting step comprises activating a disconnecting device to divide the short-circuit connection device into two separate parts.

15. The method according to any one of claims 10 to 14, wherein the EGLA is sized for ultra high pressure.

16. The method according to any one of claims 10 to 15, further comprising visually indicating (S120) an operational status of the SVU.

Technical Field

The invention relates to an external gap line arrester and a transmission line impact protection method thereof.

Background

Protection of the transmission line from the risk of flashovers caused by lightning can be achieved by using an External Gap Line Arrester (EGLA) electrically connected in parallel with the line insulator on the tower of the transmission line. EGLAs traditionally consist of a single external gap in series with a Series Varistor Unit (SVU). When lightning strikes the transmission line, the series gap is sized to spark, which turns on the SVU and allows the lightning surge current to safely transfer to ground without flashover of the line insulation. For many reasons, the SVU may be overloaded, and it is important that the lines be powered on and remain operational even if the SVU ceases to operate. Therefore, the gap distance conventionally has to be dimensioned large enough to ensure that it does not spark over, for example, a shock caused by the switch.

Due to the conflicting criteria of having to spark for lightning but not spark for switching impacts, it is difficult to achieve a proper design of the EGLA series gap. The difficulty in achieving proper design increases as the transmission voltage increases.

Disclosure of Invention

It is an object of the present invention to provide a design of EGLA that can focus primarily on spark discharges for lightning.

According to a first aspect, an External Gap Line Arrester (EGLA) for a power transmission line is presented. The EGLA includes a Series Varistor Unit (SVU) having a first end and a second end, the SVU configured to be connected between a power line and ground, a main spark discharge gap unit connected in series to the first end of the SVU, an auxiliary gap disposed between the second end of the SVU and ground, the auxiliary gap connected in series to the second end of the SVU, a short circuit connection device connected in parallel with the auxiliary gap, and a disconnect device disposed in the short circuit connection device, the disconnect device configured to disconnect the short circuit connection device when the SVU is overloaded.

With the proposed EGLA, a proper design of the EGLA is facilitated by a controlled increase of the second series gap. Although the proposed EGLA is most useful for ultra high voltage applications, it can also be used for lower and higher voltage applications.

The main spark discharge gap cell may be configured to spark discharge for lightning strikes and for switching strikes, but not for power frequency Temporary Overvoltage (TOV).

The main spark discharge gap cell may be configured to spark over lightning strikes and not over TOV sparks.

The auxiliary gap may be configured not to spark discharge for switching shocks.

The auxiliary gap, along with the main spark discharge gap, may be configured not to strike a spark discharge for the switch.

The disconnecting means may be configured to disconnect the short-circuit connection means by dividing the short-circuit connection means into two separate parts.

EGLAs may be sized for ultra high pressures.

The short-circuit connection device may be a visual fault indicator of the SVU.

The disconnect device may comprise an explosive charge having a passive trigger.

According to a second aspect, a method for impact protection of a power transmission line is presented. The method is performed in an EGLA and includes disconnecting, by a disconnecting device, a short-circuit connection device arranged in parallel with an auxiliary gap arranged in series between a second end of the SVU and ground, by spark discharge of a main spark discharge gap unit connected in series between the first end of the SVU and the transmission line, when the SVU connected between the transmission line and ground is overloaded.

The voltage of the spark discharge may be caused by lightning strikes or switching strikes rather than by TOVs.

The auxiliary gap may be configured not to spark discharge for switching shocks.

The auxiliary gap, along with the main spark discharge gap, may be configured not to strike a spark discharge for the switch.

The disconnecting step may comprise activating a disconnecting means to divide the short-circuit connection means into two separate parts.

EGLAs may be sized for ultra high pressures.

The method may also include visually indicating an operating state of the SVU.

In general, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, device, component, module, step, etc" are to be interpreted openly as referring to at least one instance of the element, device, component, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic illustration of an EGLA according to embodiments presented herein;

fig. 2 is a schematic illustration of an EGLA according to embodiments presented herein;

FIG. 3 is a schematic view showing EGLA in relation to a pylon insulator; and

fig. 4 is a flow chart illustrating a method for embodiments presented herein.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout the specification.

The physical air gap spacing or strike distance between electrodes in an External Gap Line Arrester (EGLA) defines, in part, the critical flashover voltage (CFO) for a given surge. Furthermore, the shape or form of the gap electrode also plays a role, and this defines the so-called "gap factor" which has an effect on the probability of a flashover for a given surge or shock. A large gap spacing with a high gap factor may be required to ensure that the EGLA does not flash over for switching surges when the Series Varistor Unit (SVU) of the EGLA is inoperative. However, sufficient spacing with a high clearance factor for switching shocks may not be achievable with the particular configuration otherwise required for proper operation for lightning strikes. By adding the auxiliary gap in series, the primary gap can be easily designed to cope with lightning strikes only when the SVU is not in operation, and the introduction of the auxiliary gap allows handling of switch strikes of limited magnitude without flashovers. The gap factor can be improved by having more than one gap in series.

The auxiliary series gap is increased according to the state of the SVU as a means to increase the switching surge withstand voltage (SIWV)/Base Switching Level (BSL) of the EGLA to withstand a switching inductive surge of a greater order of magnitude. This is important for ultra high voltage applications but is also useful for lower voltage applications.

By controlled addition of the auxiliary series gap, the main series gap can be designed to handle lightning strikes, switching strikes, and power frequency Temporary Over Voltages (TOVs) only when the SVU is not operating. By introducing an auxiliary gap, performance can be improved for a defined magnitude of switching surge and in the event of an SVU fault without flashover of line insulation. The primary series gap may, for example, be designed to spark over lightning strikes and switch strikes during normal operation, since the secondary series gap together with the primary gap will prevent spark over switch strikes when the SVU is not operating. The auxiliary series gap can also be designed to prevent spark discharge against a switching surge, regardless of the main gap.

An embodiment of an EGLA for a power transmission line is given with reference to fig. 1. The transmission line is supported by a transmission line tower through a line insulator. The EGLA is disposed between the transmission line and the transmission line tower and is electrically parallel to the line insulator. EGLA includes a main spark discharge gap between the first end of SVU 1 and the transmission line. EGLA also includes an auxiliary gap between the second end of SVU 1 and ground (through the power line tower). The SVU 1, the main spark discharge gap and the auxiliary spark discharge gap are connected in series. The EGLA further comprises a short-circuit connection device 3 connected in parallel with the auxiliary gap, and a disconnection device 4 arranged in the short-circuit connection device 3.

SVU 1 includes three varistors 1a, 1b and 1c connected in series by flexible links. However, the number of series varistors may be adapted according to the transmission voltage of the transmission line.

The main spark discharge gap is provided by a main spark discharge gap unit 8 comprising a suspension insulator 5 having gap electrodes 2a and 2b at its ends. In the case of a design that only takes into account lightning strike and TOV, it is simple for a person skilled in the art to choose the specific details of the suspension insulator and the gap electrode.

The auxiliary gap is above the suspension insulator 6. In case the design considerations do not allow for switching shocks on the main spark discharge gap and the auxiliary spark discharge gap, it is simple for a person skilled in the art to choose the specific details of the suspension insulator.

The short-circuit connection 3 is an electrically conductive connection between the second terminal of SVU 1 and ground. It may be in the form of, for example, a wire, cable, chain, conductor, rod, tube, linkage or other suitable means for passing an electric current.

The disconnection means 4 are configured to trigger operation at a predetermined overload current. The breaking means 4 may for example comprise an explosive charge with a passive trigger.

The short-circuit connection device 3 may also serve as an operating status indicator for the SVU 1. After the SVU 1 is overloaded, the disconnecting device 4 divides the conductor of the short-circuit connection device 3 into two separate parts, which will thereafter hang directly from SVU 1 and ground, respectively. From a distance, even from the ground or the air, it can be readily seen that the SVU 1 is no longer operating as intended. Although the disconnection means 4 is shown as being arranged in the middle of the short-circuit connection means 3, in other variants it may be arranged in a different part of the short-circuit connection means 3. It may for example be arranged close to the SVU 1, resulting in the short-circuit connection 3 hanging down along the transmission line tower, or for example close to the transmission line tower, resulting in the short-circuit connection 3 hanging down from the SVU 1.

The transmission line to which the EGLA is configured to attach during use may be an extra high voltage transmission line. The ground to which the EGLA is configured to attach during use may be a transmission tower for a transmission line.

An embodiment of an EGLA for a power transmission line is given with reference to fig. 2. The transmission line is supported by a transmission line tower through a line insulator. The EGLA is disposed between the transmission line and the transmission line tower and is electrically parallel to the line insulator. EGLA includes a main spark discharge gap between the first end of SVU 1 and the transmission line. The EGLA also includes an auxiliary gap between the second end of the SVU 1 and ground (through the transmission line tower). The SVU 1, the main spark discharge gap and the auxiliary spark discharge gap are arranged in series. The EGLA further comprises a short-circuit connection device 3 in parallel with the auxiliary gap, and a disconnection device 4 arranged in the short-circuit connection device 3.

SVU 1 includes three varistors 1a, 1b and 1c connected in series by flexible or fixed links. The number of varistors may be adapted according to the transmission voltage of the transmission line. The second end of the SVU 1 may be provided with a bottom weight 7 to keep the EGLA hanging relatively immovably directly down.

The main spark discharge gap is arranged by a main spark discharge gap unit 8 comprising a suspension insulator 5 having gap electrodes 2a and 2b at its ends. In the case of a design that only takes into account lightning strike and TOV, it is simple for a person skilled in the art to choose the specific details of the suspension insulator and the gap electrode.

The auxiliary gap is above the air. In case of design considerations that do not allow for switching shocks on the main spark discharge gap and the auxiliary gap, it is simple for a person skilled in the art to choose the specific details of the air gap.

The short-circuit connection 3 is an electrically conductive connection between the second terminal of SVU 1 and ground. It may be in the form of, for example, a wire, cable, chain, conductor, rod, tube, linkage or other suitable means for passing an electric current.

The disconnection means 4 are configured to trigger operation at a predetermined overload current. The breaking means 4 may for example comprise an explosive charge with a passive trigger.

The short-circuit connection device 3 may also serve as an operating status indicator for the SVU 1. After the SVU 1 is overloaded, the disconnecting device 4 divides the conductor of the short-circuit connection device 3 into two separate parts, which will thereafter hang directly from SVU 1 and ground, respectively. From a distance, even from the ground or the air, it can be readily seen that the SVU 1 is no longer operating as intended. Although the disconnection means 4 is shown as being arranged in the middle of the short-circuit connection means 3, in other variants it may be arranged in a different part of the short-circuit connection means 3. It may for example be arranged close to the SVU 1, resulting in the short-circuit connection 3 hanging down along the transmission line tower, or for example close to the transmission line tower, resulting in the short-circuit connection 3 hanging down from the SVU 1.

An embodiment of an EGLA for a power transmission line is given with reference to fig. 1 and 2. The EGLA comprises a SVU 1 having a first end and a second end, the SVU 1 being configured to be connected between the transmission line and ground, a main spark discharge gap unit 8 connected in series to the first end of the SVU 1, an auxiliary gap arranged between the second end of the SVU 1 and ground and connected in series to the second end of the SVU 1, a short-circuit connection device 3 connected in parallel with the auxiliary gap, and a disconnection device 4 arranged in the short-circuit connection device, the disconnection device being configured to disconnect the short-circuit connection device when the SVU is overloaded.

The main spark discharge gap cell may be configured to spark out for lightning strikes and for switching strikes, but not for TOVs.

The main spark discharge gap unit may alternatively also be designed not for switching shocks but still for lightning-shocking spark discharges.

The auxiliary gap may be configured not to spark discharge for switching shocks.

When the SVU is overloaded, the auxiliary gap, along with the main gap, may be configured not to spark over the switching surge.

The disconnecting means may comprise an explosive charge configured to disconnect the short-circuit connection means 3 by dividing the short-circuit connection means 3 into two separate parts.

EGLA may be sized for ultra high voltages, i.e. above 800 kV.

The short-circuit connection device may be a visual fault indicator of the SVU.

The embodiment shown in connection with fig. 1 and 2 is schematically shown in a view parallel to the transmission line. Fig. 3 schematically shows the arrangement of EGLAs in a view perpendicular to the transmission line. The line insulator 10 is arranged between the transmission line and the transmission line tower and the EGLA is arranged between the transmission line and the tower, i.e. electrically in parallel with the insulator 10. The line insulator may be, for example, a tension insulator or a suspension insulator.

Although the EGLAs have been shown in the drawings as being disposed from the transmission line down to the transmission tower mast, the EGLAs may alternatively be disposed from the transmission line support cross arms down to the transmission line.

Referring to fig. 4, an embodiment of a method for impact protection of a power transmission line is presented. The method is performed in an EGLA and comprises, when an SVU connected between the transmission line and ground is overloaded S100, disconnecting S110 a short-circuit connection device by a disconnection device through spark discharge of a main spark discharge gap unit connected in series between a first end of the SVU and the transmission line, the short-circuit connection device being arranged in parallel with an auxiliary gap arranged in series between a second end of the SVU and ground. The disconnection means is arranged at the short-circuit connection means.

The voltage of the spark discharge may be caused by lightning strikes or switching strikes rather than by TOVs.

The auxiliary gap may be configured not to spark discharge for switching shocks.

When the SVU is overloaded, the auxiliary gap, along with the main spark discharge gap, may be configured not to strike spark discharges against the switch.

The step of disconnecting may comprise initiating an explosive charge to disconnect the short circuit connection means into two separate parts.

EGLAs may be sized for ultra high pressures.

The method may also include visually indicating the operational status of the S120 SVU.

The invention has mainly been described above with reference to a few embodiments. However, a person skilled in the art will readily appreciate that other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.