A self-discharge gap type controllable arrester and a self-discharge gap

Abstract

The application discloses a self-discharge gap type controllable lightning arrester and a self-discharge gap. The self-discharge gap type controllable lightning arrester comprises a self-discharge gap, and the self-discharge gap is connected in parallel with a controllable part of the lightning arrester, wherein the self-discharge gap has insulation characteristics. The self-discharge gap can self-discharge under lightning / high-amplitude operating overvoltage, bypass the controllable part quickly, and deeply inhibit the lightning / operating overvoltage. The self-discharge gap can support the cancellation of closing resistors of an extra-high voltage system and an ultra-high voltage system, improve the safety margin of a power grid and equipment, and reduce the size of external insulation.

Description

Technical Field

[0001] This invention relates to the field of high-voltage electrical technology in power systems, and more specifically, to a self-discharge gap type controllable surge arrester and a self-discharge gap. Background Technology

[0002] With the construction of ultra-high voltage and extra-high voltage power grids, there is an urgent need to use controllable surge arresters to deeply suppress overvoltages. Controllable surge arresters use control switches to activate and deactivate the controllable valve section. Under overvoltage, the controllable valve section deactivates, which can deeply suppress overvoltages and improve energy absorption capacity; after the overvoltage, the controllable valve section activates, ensuring the reliability of the controllable surge arrester's operation. The control switch is the core component. In the past three years, controllable surge arresters for ultra-high voltage and extra-high voltage AC / DC power grids have been successively demonstrated and applied. The control switches have taken the form of circuit breakers, thyristor valves, and controlled trigger gaps, etc., each with its own shortcomings such as slow operating speed, complex structure and control, and complex control. They can only suppress some operational overvoltages, and they also occupy a large area and have high costs. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a self-discharge gap type controllable surge arrester and a self-discharge gap.

[0004] According to one aspect of the present invention, a self-discharge gap type controllable surge arrester is provided, comprising: a self-discharge gap, wherein the self-discharge gap is connected in parallel with the controllable part of the surge arrester, and wherein the self-discharge gap has insulating characteristics.

[0005] Optionally, the insulation technical requirements for the self-discharge gap are as follows: power frequency / DC withstand voltage = continuous operating voltage of the entire surge arrester * controllability ratio * 1.1; switching impulse discharge voltage = maximum operating residual voltage of the entire surge arrester * controllability ratio * suppression coefficient * 0.95; lightning impulse discharge voltage = maximum lightning residual voltage of the entire surge arrester * controllability ratio * suppression coefficient * 0.95.

[0006] Optionally, the self-discharge gap is installed in parallel with the controllable part of the surge arrester via a disconnecting switch. The moving contact of the disconnecting switch is connected to the high-voltage inlet at the top of the self-discharge gap, and the stationary contact is installed at the high-voltage end of the controllable part of the surge arrester, allowing for replacement of the gap body when the controllable function is temporarily deactivated; or

[0007] Two self-discharge gaps are installed in parallel with the controllable part of the surge arrester via a disconnecting switch. The moving contact of the disconnecting switch is connected to the high-voltage end of the controllable part of the surge arrester. The first stationary contact is installed at the high-voltage inlet at the top of one of the self-discharge gaps, and the second stationary contact is installed at the high-voltage inlet at the top of the other self-discharge gap. The two self-discharge gaps and the insulating support of the disconnecting switch are arranged in an equilateral triangle to meet the requirements for replacing the gap body during live-line work.

[0008] According to another aspect of the present invention, a self-discharge gap is provided, comprising: a composite jacket and a metal transition barrel, wherein...

[0009] The composite jacket has a metal cover plate at the top and is connected to a metal transition barrel at the bottom via a flange.

[0010] The composite jacket contains an upper electrode, a lower electrode, an upper shielding ring, a lower shielding ring, an upper conductive rod, and a lower conductive rod. The upper end of the upper conductive rod is connected to the upper cover plate of the composite jacket, and the lower end is connected to the upper shielding ring and the upper electrode. The lower end of the lower conductive rod is installed on the insulating support platform inside the metal transition barrel, and the upper end is installed with the lower shielding ring and the lower electrode.

[0011] The metal transition barrel is equipped with a gas density gauge and a gas filling valve.

[0012] Optionally, the composite jacket is insulated with SF6 or SF6 / N2 mixed gas.

[0013] Optionally, the upper cover plate is connected to the high-voltage lead wire, which is led out from the low-voltage outlet bushing through the upper and lower electrodes. The low-voltage outlet bushing and the metal transition barrel are designed with insulation to prevent the ground potential of the bracket from rising when a large current enters the ground.

[0014] Optionally, the upper and lower electrodes are made of CuW70 or CuW80 material that is resistant to arc erosion. The upper and lower electrodes are flat spiral groove self-magnetic field rotating arc electrodes, which are used to control the arc to rotate at high speed along the electrode surface and prevent arc erosion from affecting the gap insulation characteristics when current is passed.

[0015] Optionally, the non-uniformity coefficient of the gap electric field generated by the applied voltage to the upper and lower electrodes is less than 1.05, and the maximum electric field does not appear at the spiral groove opening of the upper and lower electrodes.

[0016] Optionally, the upper and lower shielding rings constitute the primary capacitor of the capacitor divider. The potential of the lower shielding ring is led out through the terminal block on the metal transition barrel using a coaxial cable and connected to the secondary capacitor of the capacitor divider. The capacitor divider is used to measure the self-discharge gap voltage.

[0017] An external current coil is installed at any position from the low-voltage outgoing bushing of the self-discharge gap body to the low-voltage outgoing line of the controllable part of the surge arrester. The external current coil has two different ranges to measure the leakage current of the fixed part in the range of hundreds of μA to several A and the operating current of the fixed part in the range of kA.

[0018] Therefore, this application provides a self-discharge gap capable of self-discharging under high-amplitude lightning / operational overvoltages, quickly bypassing the controllable portion, and deeply suppressing lightning / operational overvoltages. This can support the elimination of closing resistors in ultra-high voltage and extra-high voltage systems, improving the safety margin of the power grid and equipment, and reducing the size of external insulation. Attached Figure Description

[0019] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0020] Figure 1 This is a schematic diagram of a self-discharge gap type controllable surge arrester provided in the first aspect of the present invention;

[0021] Figure 2a , Figure 2b This is a schematic diagram of the dual-redundancy scheme structure of the self-discharge gap-controlled controllable surge arrester provided in the first aspect of the present invention.

[0022] Figure 3a , Figure 3b This is another structural schematic diagram of the self-discharge gap-controlled controllable surge arrester provided in the first aspect of the present invention.

[0023] Figure 4 This is a schematic diagram of the structure of the self-discharge gap provided in the second aspect of the present invention;

[0024] Figure 5 This is a schematic diagram of a controllable surge arrester based on a self-discharge gap provided in the second aspect of the present invention.

[0025] Figure 6 This is a schematic diagram of the structure of the upper electrode and the lower electrode provided in the second aspect of the present invention; Detailed Implementation

[0026] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0027] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0028] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0029] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0030] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0031] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0032] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0033] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0034] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0037] Figure 1 This is a schematic diagram of the structure of a self-discharge gap type controllable surge arrester provided in the first aspect of the present invention. (See diagram below.) Figure 1 As shown, a self-discharge gap type controllable surge arrester includes: a self-discharge gap 10, which is connected in parallel with the controllable part 20 of the surge arrester, wherein the self-discharge gap 10 has insulation characteristics.

[0038] Optionally, the insulation technical requirements for the self-discharge gap 10 are as follows: power frequency / DC withstand voltage = continuous operating voltage of the entire surge arrester * controllability ratio * 1.1; switching impulse discharge voltage = maximum operating residual voltage of the entire surge arrester * controllability ratio * suppression coefficient * 0.95; lightning impulse discharge voltage = maximum lightning residual voltage of the entire surge arrester * controllability ratio * suppression coefficient * 0.95.

[0039] Optionally, refer to Figure 2a , Figure 2b , Figure 3a and Figure 3bAs shown, the self-discharge gap 10 is installed in parallel with the controllable part 20 of the surge arrester via a disconnecting switch 30. The moving contact of the disconnecting switch 30 is connected to the high-voltage input at the top of the self-discharge gap 10, and the stationary contact is installed at the high-voltage end of the controllable part 20 of the surge arrester, allowing for replacement of the gap body when the controllable function is temporarily deactivated; or

[0040] Two self-discharge gaps 10 are connected in parallel with the controllable part 20 of the surge arrester via a disconnecting switch 30. The moving contact of the disconnecting switch 30 is connected to the high-voltage end of the controllable part 30 of the surge arrester. The first stationary contact 31 is installed at the high-voltage inlet at the top of one of the self-discharge gaps 10, and the second stationary contact 32 is installed at the high-voltage inlet at the top of the other self-discharge gap 10. The two self-discharge gaps 10 and the insulating support of the disconnecting switch 30 are arranged in an equilateral triangle to meet the requirements for replacing the gap body during live-line work.

[0041] Furthermore, according to the second aspect of this application, Figure 4 This is a schematic diagram of the self-discharge gap provided in the first aspect of an embodiment of the present invention. (See attached diagram.) Figure 4 As shown, the self-discharge gap includes: a composite jacket 1 and a metal transition barrel 2, wherein...

[0042] The upper end of the composite jacket 1 is provided with a metal cover plate 3, and the lower end is connected to the metal transition barrel 2 through a flange 4;

[0043] The composite jacket 1 is equipped with an upper electrode 5, a lower electrode 6, an upper shielding ring 71, a lower shielding ring 72, an upper conductive rod 81, and a lower conductive rod 82. The upper end of the upper conductive rod 81 is connected to the upper cover plate 3 of the composite jacket 1, and the lower end is connected to the upper shielding ring 71 and the upper electrode 5. The lower end of the lower conductive rod 82 is installed on the insulating support platform 21 inside the metal transition barrel 2, and the upper end is equipped with the lower shielding ring 72 and the lower electrode 6.

[0044] The metal transition tank 2 is equipped with a gas density gauge and a gas filling valve 9.

[0045] Optionally, the composite jacket 1 is insulated with SF6 or SF6 / N2 mixed gas.

[0046] Optionally, the upper cover plate 3 is connected to the high-voltage lead wire, which is led out from the low-voltage outlet bushing 22 through the upper electrode 5 and the lower electrode 6. The low-voltage outlet bushing and the metal transition barrel are designed with insulation to prevent the ground potential of the bracket from rising when a large current enters the ground.

[0047] Optionally, the upper electrode 5 and the lower electrode 6 are made of CuW70 or CuW80 material that is resistant to arc erosion. The upper electrode 5 and the lower electrode 6 are flat spiral groove self-magnetic field arc rotating electrodes, which are used to control the arc to rotate at high speed along the electrode surface and prevent arc erosion from affecting the gap insulation characteristics when current is passed.

[0048] Optionally, the non-uniformity coefficient of the gap electric field generated by the applied voltage to the upper electrode 5 and the lower electrode 6 is less than 1.05, and the maximum electric field does not appear at the spiral groove opening of the upper electrode 5 and the lower electrode 6.

[0049] Optionally, the upper shielding ring 71 and the lower shielding ring 72 constitute the primary capacitor of the capacitor divider. The potential of the lower shielding ring 72 is led out through the upper terminal of the metal transition barrel 2 using a coaxial cable and connected to the secondary capacitor of the capacitor divider. The capacitor divider is used to measure the self-discharge gap voltage.

[0050] An external current coil is installed at any position from the self-discharge gap 10, the low-voltage outgoing bushing of the main body to the controllable part 20, the low-voltage outgoing line of the surge arrester. The external current coil has two different ranges to measure the leakage current of the fixed part in the range of hundreds of μA to several A and the operating current of the fixed part in the range of kA.

[0051] Specifically, refer to Figure 5 As shown, the surge arrester for ultra-high voltage AC projects is designed with a fixed section and a controllable section 20 connected in series. A self-discharge gap 10 is connected in parallel within the controllable section 20, forming a structure as shown... Figure 1 The diagram shows a self-discharge gap-controlled surge arrester. During normal system operation, the gap is insulated, and both the fixed and controllable sections are engaged, ensuring no reduction in the long-term operating charge rate of the arrester's varistor. When a high-amplitude overvoltage occurs, the gap self-discharge rapidly bypasses the controllable section, leaving only the fixed section operational, effectively suppressing the overvoltage. After the overvoltage ends, the current in the fixed section of the arrester decreases to the μA–mA level, the gap automatically extinguishes the arc and insulation is restored, and the controllable section is then engaged. During the period from arc extinguishing to insulation restoration, the fixed section of the arrester experiences a short-term overload; therefore, the gap must quickly restore insulation.

[0052] Self-discharge gap technical requirements: In order to achieve the above functions, the following requirements are proposed for the insulation, current carrying capacity, and insulation recovery of the self-discharge gap:

[0053] a. Insulation aspects

[0054] The self-discharge gap 10 should reliably insulate during normal system operation and reliably self-discharge in the event of high-amplitude overvoltages. For surge arresters with a controllability ratio of x%, to suppress high-amplitude lightning and switching overvoltages to (1-x%), the following gap withstand voltage and discharge requirements are proposed:

[0055] The gap should reliably withstand the power frequency operating voltage U0*x%, with a margin of at least 10%. The power frequency withstand voltage of the gap should not be lower than U0*x%*1.1.

[0056] Under high-amplitude operating residual voltage x%*U1, the gap should reliably self-discharge. Considering at least a 5% margin, the gap operating discharge voltage should not exceed U1*x%*(1-x%)*0.95.

[0057] For high-amplitude lightning strikes, the gap should reliably self-discharge at a rate of (1-x%) of x%*U2, with a margin of at least 5%. The gap operation discharge voltage should not exceed U2*x%*(1-x%)*0.95.

[0058] b. Current carrying capacity and insulation restoration

[0059] After the self-discharge gap 10 discharges under overvoltage, it should be able to carry current and quickly restore insulation after the overvoltage ends. The current carrying capacity of the self-discharge gap 10 is analyzed based on three scenarios: power frequency, switching, and lightning overvoltage, with power frequency overvoltage being the primary condition. The most stringent current carrying condition for the gap is when a maximum power frequency overvoltage occurs again after a switching overvoltage, lasting 0.3 seconds. After this current carrying, the insulation recovery time of the gap should be less than the overload withstand time of the fixed part of the surge arrester, with a margin of not less than 20%.

[0060] Specifically, Figure 5 This is a schematic diagram showing the installation of a controllable surge arrester and a self-discharge gap. The self-discharge gap uses a composite outer jacket structure insulated with SF6 or SF6 / N2 mixed gas. The internal structure of the gap is as follows: Figure 1 As shown. The gap body includes a composite jacket 1 and a metal transition tank 2. The upper end of the composite jacket is a metal cover plate 3, and the lower end is connected to the metal transition tank 2 via a flange 4. Inside, an upper electrode 5, a lower electrode 6, an upper shielding ring 71, a lower shielding ring 72, an upper conductive rod 81, and a lower conductive rod 82 are installed. The upper end of the upper conductive rod 81 is connected to the upper cover plate 3 of the composite jacket 1, and the lower end is connected to the upper shielding ring 71 and the upper electrode 5. The lower conductive rod 82 is installed on an insulating support platform 21 inside the metal transition tank 2, and the upper end is equipped with the lower shielding ring 72 and the lower electrode 6. A gas density gauge inflation valve 9 is installed on the metal transition tank 2 for gap inflation and pressure monitoring.

[0061] The high-voltage lead is connected to the high-voltage conductive rod of the upper cover plate 3 and introduced into the gap to connect to the high-voltage electrode. The low-voltage electrode of the gap is placed on the low-voltage conductive rod and led out through the low-voltage outgoing bushing 22 on the metal transition barrel 2. After being gathered with the arrester down conductor, it is connected to the controllable arrester counter and detection unit.

[0062] In addition, the self-discharge gap 10 can be equipped with an external current coil to measure the gap current. Using the upper shielding ring 71, lower shielding ring 72, and the capacitor between flange 4 as a primary capacitor, the potential of the lower shielding ring 72 is led out through the terminal block on the metal transition barrel 2 and connected to a secondary capacitor module to form a capacitor divider for measuring the gap voltage. The gap voltage and current analog quantities are locally converted into optical signals and transmitted remotely to the background monitoring system.

[0063] Furthermore, the insulation design of the self-discharge gap in this application is as follows: the gap adopts parallel plate electrodes to form a gas gap with a slightly non-uniform field as shown in Figure 3, the gap impact coefficient is reduced to below 1.3 by increasing the chamfer of the electrode edge, and the polarity effect is reduced by adopting a composite jacket structure.

[0064] Furthermore, the self-discharge gap current-carrying and insulation restoration design of this application: the upper electrode 5 and the lower electrode 6 are spiral groove self-magnetic field rotating arc electrodes, such as... Figure 6 As shown, ablation-resistant CuW70 or CuW80 materials are used. After the gap self-discharges, the arc rotates at high speed around the electrode edge under the action of the self-magnetic field, reducing the local ablation of the electrode by the arc, enhancing the ablation resistance of the electrode, extending the electrode life after triggering the gap current flow, and realizing large current flow and rapid insulation recovery after current flow.

[0065] In addition, the status monitoring strategy involves real-time monitoring of the gap current and voltage during self-discharge. Under normal system operation, the gap should reliably insulate against current flow; however, during abnormal discharge, leakage current from the fixed section will flow. In the event of overvoltage, the gap should discharge current through the fixed section's operating current. When current is detected in the gap, the gap discharge voltage is obtained by correlating it with the gap voltage. If the gap self-discharge voltage decreases, appropriate gas replenishment is performed to improve gap insulation.

[0066] Since the gap current measurement system needs to accurately measure the leakage current of fixed parts in the range of hundreds of μA to several A and the operating current of fixed parts in the range of kA, the measurement principle is as follows:

[0067] A small current sensor (Rogowski coil, current transformer, Hall sensor) collects the parameters of the limiter (resistance, MOV, TVS) to obtain a small current, which is then passed through a small current conditioning amplifier.

[0068] A high-current sensor (Rogowski coil, current transformer) collects attenuator parameters to obtain a high current, which is then passed through a high-current conditioning amplifier.

[0069] Two current sensors with different ranges are used at the low-voltage outlet bushing to measure both small and large currents. A passive limiting clamping circuit is used to limit the output voltage of the small current sensor to prevent damage to the secondary amplifier circuit due to excessive output voltage.

[0070] The gap voltage measurement uses a capacitive voltage divider. The primary capacitor of the voltage divider is formed by upper and lower shielding rings. The potential of the lower shielding ring is led out via a coaxial cable through the terminals on a metal transition barrel, and connected to an external secondary capacitor and an analog signal acquisition module.

[0071] Therefore, this application provides a self-discharge gap capable of self-discharging under high-amplitude lightning / operational overvoltages, quickly bypassing the controllable portion, and deeply suppressing lightning / operational overvoltages. This can support the elimination of closing resistors in ultra-high voltage and extra-high voltage systems, improving the safety margin of the power grid and equipment, and reducing the size of external insulation.

[0072] The self-discharge gap it provides allows for self-discharge under high-amplitude overvoltages, effectively suppressing operational and lightning overvoltages. After the overvoltage ends, it self-extinguishes the arc and rapidly restores insulation. Suitable for ultra-high voltage AC power grids, it is simple, reliable, compact, and low-cost.

[0073] The self-discharge gap type controllable surge arrester and the self-discharge gap provided in this application can achieve parallel installation of the gap and the controllable part of the surge arrester without changing the original surge arrester structure. Only by adding a fixed support to the surge arrester mounting bracket, the gap can be installed in parallel with the controllable part of the surge arrester.

[0074] Based on the control method and self-discharge gap design method of the self-discharge gap controlled surge arrester described above, a self-discharge gap was designed for an ultra-high voltage AC controlled surge arrester with a controllability ratio of 15%, based on an overvoltage suppression of 15%. The structure of the self-discharge gap controlled surge arrester is as follows: Figure 5 As shown.

[0075] The gap employs a composite jacket structure with built-in parallel flat electrodes, creating a slightly non-uniform field. The insulation is provided by a mixed gas at a pressure of 0.18 MPa (absolute pressure, the same below), with a gap distance of 12 mm. The key performance test results for insulation and current carrying capacity are as follows:

[0076] The self-discharge gap can reliably withstand power frequency of 0.15*1.1 PU and discharge at 0.15*1.22 PU.

[0077] The lightning discharge voltage U99 is 173.3kV for negative polarity and 177.3kV for positive polarity, which is lower than 0.85*0.15*1.8pu (204kV). At the maximum lightning residual voltage peak of 0.15*1.8pu, the discharge voltage increases due to the increased voltage slope; the negative polarity discharge voltage is 75.5%–80.2% of the maximum residual voltage, and the positive polarity discharge voltage is 73.3%–83.9% of the maximum residual voltage. This meets the requirement of a 15% reduction in lightning residual voltage.

[0078] The operating discharge voltage U99 is 179.3kV for negative polarity and 173.4kV for positive polarity, which is lower than 0.85*0.15*1.62pu (185kV). At the maximum operating residual voltage peak of 0.15*1.62pu, the discharge voltage increases due to the increased voltage slope; the negative discharge voltage is 65.3%–83.2% of the maximum residual voltage, and the positive discharge voltage is 66.5%–77.7% of the maximum residual voltage. This meets the requirement of a 15% reduction in operating residual voltage.

[0079] The current carrying capacity and insulation recovery test is conducted according to the principle of equivalent current carrying capacity. The test is carried out at twice the maximum current carrying capacity of the gap discharge under the comprehensive consideration of lightning, power frequency and switching overvoltage. After the gap arc is extinguished, it can recover to withstand 0.15*1.0 pu of power frequency in 65ms and 0.15*1.1 pu of power frequency in 100ms. The overload of the fixed part of the surge arrester has been verified to withstand the overload.

[0080] In summary:

[0081] 1. This application proposes a method for using a self-discharge gap as an ultra-high-speed control switch for a controllable surge arrester to achieve deep suppression of lightning overvoltage and switching overvoltage. Specifically, the self-discharge gap is connected in parallel with the controllable part of the surge arrester; during normal system operation, the gap is reliably insulated, and both the fixed and controllable parts of the surge arrester are engaged to ensure the long-term operational reliability of the surge arrester; when high-amplitude lightning / switching overvoltage occurs, the gap self-discharge bypasses the controllable part, leaving the fixed part, significantly reducing the residual lightning / switching voltage.

[0082] 2. This application proposes technical requirements for the self-discharge gap that can achieve the above scheme, including withstand voltage requirements, discharge voltage requirements, and insulation recovery time requirements after current flow.

[0083] 3. This application proposes a self-discharge gap design that meets the above requirements. This includes a composite jacket structure, SF6 or SF6 / N2 gas insulation, and an integral structure. Parallel plate electrodes are used to create a slightly non-uniform gas gap, reducing the impact coefficient to approximately 1.3 and mitigating polarity effects. Spiral groove self-magnetic field electrodes are used to achieve rapid insulation recovery after current flow, reducing the overload time of the fixed section.

[0084] 4. This application proposes a method for monitoring the status of self-discharge gaps in engineering applications. Specifically, it involves real-time monitoring of the gap voltage and current, and determining whether the gap insulation status is normal based on the voltage value at the moment the gap current occurs. If the insulation deteriorates, a small amount of gas is promptly added.

[0085] 5. This application proposes a method for accurately measuring gap current. Specifically, during normal system operation, abnormal gap self-discharge results in a fixed leakage current in the hundreds of μA-mA range; under overvoltage conditions, gap discharge results in a fixed operating current in the kA range. Two current sensors with different ranges are used to measure both small and large currents. A passive limiting clamping circuit is used to limit the output voltage of the small current sensor to prevent damage to the secondary amplifier circuit due to excessively high output voltage.

[0086] 6. This application proposes a method for measuring the gap voltage by using a primary capacitor with uniform upper and lower capacitors within the gap and an external secondary capacitor to construct a capacitor voltage divider.

[0087] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A self-discharge gap type controllable surge arrester, characterized in that, include: A self-discharge gap (10) is connected in parallel with the controllable part (20) of the surge arrester, wherein the self-discharge gap (10) has insulating properties; The insulation technical requirements for the self-discharge gap (10) are as follows: power frequency / DC withstand voltage = continuous operating voltage of the entire surge arrester * controllable ratio * 1.1; switching impulse discharge voltage = maximum operating residual voltage of the entire surge arrester * controllable ratio * suppression coefficient * 0.95; lightning impulse discharge voltage = maximum lightning residual voltage of the entire surge arrester * controllable ratio * suppression coefficient * 0.95; The self-discharge gap (10) is installed in parallel with the controllable part (20) of the surge arrester via a disconnecting switch (30). The moving contact of the disconnecting switch (30) is connected to the high-voltage inlet at the top of the self-discharge gap (10), and the stationary contact is installed at the high-voltage end of the controllable part (20) of the surge arrester, so as to meet the requirement of replacing the gap body when the controllable function is temporarily withdrawn. or The two self-discharge gaps (10) are connected in parallel with the controllable part (20) of the surge arrester via a disconnecting switch (30). The moving contact of the disconnecting switch (30) is connected to the high-voltage end of the controllable part (20) of the surge arrester. The first stationary contact (31) is installed at the high-voltage inlet at the top of one of the self-discharge gaps (10), and the second stationary contact (32) is installed at the high-voltage inlet at the top of the other self-discharge gap (10). The two self-discharge gaps (10) and the insulating support of the disconnecting switch (30) are arranged in an equilateral triangle to meet the requirements for replacing the gap body during live-line operation.

2. The self-discharge gap for a self-discharge gap type controllable surge arrester according to claim 1, characterized in that, include: Composite outer jacket (1) and metal transition barrel (2), wherein The upper end of the composite jacket (1) is provided with a metal upper cover plate (3), and the lower end is connected to the metal transition barrel (2) through a flange (4); The composite jacket (1) is equipped with an upper electrode (5), a lower electrode (6), an upper shielding ring (71), a lower shielding ring (72), an upper conductive rod (81), and a lower conductive rod (82). The upper end of the upper conductive rod (81) is connected to the upper cover plate (3) of the composite jacket (1), and the lower end is connected to the upper shielding ring (71) and the upper electrode (5). The lower end of the lower conductive rod (82) is installed on the insulating support platform (21) inside the metal transition barrel (2), and the lower shielding ring (72) and the lower electrode (6) are installed on its upper end. The metal transition barrel (2) is equipped with a gas density meter filling valve (9).

3. The self-discharge gap according to claim 2, characterized in that, The composite jacket (1) is insulated with SF6 or SF6 / N2 mixed gas.

4. The self-discharge gap according to claim 2, characterized in that, The upper cover plate (3) is connected to the high voltage lead wire, which is led out from the low voltage outlet bushing (22) through the upper electrode (5) and the lower electrode (6). The low voltage outlet bushing and the metal transition barrel are designed with insulation to prevent the ground potential of the support from rising when a large current enters the ground.

5. The self-discharge gap according to claim 2, characterized in that, The upper electrode (5) and the lower electrode (6) are made of CuW70 or CuW80 material that is resistant to arc erosion. The upper electrode (5) and the lower electrode (6) are flat spiral groove self-magnetic field rotating arc electrodes, which are used to control the arc to rotate at high speed along the electrode surface and prevent the arc erosion from affecting the gap insulation characteristics when the current is passed.

6. The self-discharge gap according to claim 2, characterized in that, The non-uniformity coefficient of the gap electric field generated by the voltage applied to the upper electrode (5) and the lower electrode (6) is less than 1.05, and the maximum electric field does not appear at the spiral groove of the upper electrode (5) and the lower electrode (6).

7. The self-discharge gap according to claim 2, characterized in that, The upper shielding ring (71) and the lower shielding ring (72) constitute the primary capacitor of the capacitor divider. The potential of the lower shielding ring (72) is led out through the terminal on the metal transition barrel (2) using a coaxial cable and connected to the secondary capacitor of the capacitor divider. The capacitor divider is used to measure the self-discharge gap voltage. An external current coil is installed at any position from the low-voltage outgoing bushing of the self-discharge gap (10) body to the low-voltage outgoing line of the controllable part (20) of the surge arrester. The external current coil is a current coil with two different ranges to measure the leakage current of the fixed part at the level of hundreds of μA to several A and the operating current of the fixed part at the level of kA.

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