A gas switch insulation recovery characteristics test device

Abstract

The present invention discloses a gas switch insulation recovery characteristic test device, wherein an energy storage capacitor, an isolation resistor, and an isolation core coil are connected in series to one end of a gas gap between two electrodes, and the other electrode of the gas gap between the two electrodes is grounded to form a discharge freewheeling circuit. The timing of outputting double nanosecond pulses is controlled by a signal generator and a low-voltage pulse generating circuit. The two pulse output ends are connected to the high-voltage end of the gas gap between the two electrodes through two isolation ball gaps. The first nanosecond pulse causes the gas gap to break down, and the breakdown voltage is U b1 , the electric energy in the energy storage capacitor is released through the freewheeling circuit; the time interval of the second nanosecond pulse acting on the gas gap can be adjusted by using the signal generator, and the breakdown voltage of the second nanosecond pulse acting on the gas gap is U b2 , U b2 / U b1 It reflects the degree of insulation recovery after the gas gap is broken down in the presence of continuous current. By changing the isolation resistance and the charging voltage of the energy storage capacitor, the insulation recovery of the gas gap under different continuous current conditions can be explored.

Description

Technical Field

[0001] The invention belongs to the technical field of insulation recovery after gas gap discharge breakdown, and in particular relates to an experimental device for testing insulation recovery characteristics of a gas switch. Background Art

[0002] The switch is one of the most important components in FLTD. Gas spark switches are widely used because of their large operating range and can be triggered under nanosecond jitter. Among them, three-electrode field distortion switches and multi-gap multi-channel switches are the most commonly used. In practical applications, FLTD usually connects modules in multiple stages in series and parallel to obtain different output parameters. Its circuit topology determines the huge number of gas switches.

[0003] When charging the energy storage capacitor in the FLTD, some gas switches will unexpectedly self-break down in advance. When a switch breaks down, it will discharge through the charging isolation resistor and the energy storage capacitor of the remaining branches to form a closed resistor-capacitor loop, which makes the switch that breaks down cannot be turned off quickly, extending the insulation recovery time of the switch. In this case, the synchronization and stability of the system operation are affected, and the life of the gas switch will be shortened due to the long-term ablation. In addition, after the discharge spark channel of the gas switch is extinguished, the withstand voltage level of the switch cannot be restored immediately. After the gas is neutralized and the gas density is restored, the insulation can be completely restored to reach the withstand voltage level before the breakdown. Therefore, it is necessary to explore the law, characteristics and influencing factors of the insulation recovery of the gas spark switch in the FLTD after self-breakdown during the charging process. This will enable us to more clearly understand the process of insulation recovery after the breakdown of the FLTD gas switch under the above working conditions, and help to select suitable key parameters such as the working gas pressure and charging isolation resistor of the gas switch in actual engineering.

[0004] At present, the research on gas gap insulation recovery at home and abroad is mainly aimed at two-electrode spark gap. Studies have shown that the insulation recovery process after the breakdown of the gas spark gap can be divided into three stages: the first stage is the restoration of the electrical neutrality of the spark channel, and the remaining space charge after the spark is extinguished is eliminated through diffusion, recombination and adhesion; the second stage is the recovery of gas density, and the spark removes the deposited energy in the form of heat through heat conduction, convection and radiation; the third stage is the recovery of the gas switch's ability to withstand overvoltage. In addition, some scholars have also explored the effects of gap distance, gas type and pressure, electrode size and other factors on insulation recovery. However, these studies are all aimed at the insulation recovery of the gas switch after breakdown without the influence of other external circuits. For the gas switch in FLTD, there are a large number of capacitors, resistors, and gas switches in series and parallel, making it difficult to directly measure the insulation recovery characteristics of the gas switch after self-breakdown in FLTD. There is currently no research platform and method for the insulation recovery of the gas switch in FLTD after self-breakdown discharge. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a gas switch insulation recovery characteristic test device in view of the deficiencies in the above-mentioned prior art, which equivalently simulates the situation in which the gas switch in the FLTD forms a resistor-capacitor discharge circuit with the energy storage capacitors of other branches and the isolation resistor after self-breakdown discharge during the charging process, and then measures the insulation recovery of the gas switch gap after breakdown.

[0006] The present invention adopts the following technical solutions:

[0007] A gas switch insulation recovery characteristic test experimental device comprises a dual nanosecond pulse timing control circuit, wherein the input end of the dual nanosecond pulse timing control circuit is connected to a signal generator, and the output end is connected to the high-voltage end of the two-electrode gas gap in a freewheeling discharge circuit through two isolation ball gaps. The timing of the dual nanosecond pulses is output to the freewheeling discharge circuit through the signal generator, the first nanosecond pulse is used for gas gap breakdown, and electric energy is released through the freewheeling circuit; the second nanosecond pulse acts on the gas gap, and the freewheeling discharge circuit is connected to an oscilloscope via a high-voltage probe.

[0008] Specifically, the high-voltage end of the gas gap between the two electrodes is divided into two paths, one path is connected to the oscilloscope via a high-voltage probe, and the other path is connected to the isolation ball gap. The gas gap between the two electrodes, the isolation coil, the isolation resistor and the energy storage capacitor are connected in series to form a discharge circuit. The isolation resistor and the energy storage capacitor are connected in parallel with one end of the charging resistor, and the other end of the charging resistor is respectively connected to the gas gap between the two electrodes and the high-voltage probe.

[0009] Furthermore, the gas gap between the two electrodes is formed by a sealed insulating shell and two stainless steel metal electrodes, the distance between the two stainless steel metal electrodes is 2.5-10 mm, and the isolation coil is wound by a high-voltage wire and a toroidal ferrite core.

[0010] Furthermore, the inductance of the isolation coil is greater than 500 μH.

[0011] Furthermore, a coaxial shunt is connected in series between the energy storage capacitor and the ground wire, and the coaxial shunt is connected to the oscilloscope.

[0012] Specifically, the dual nanosecond pulse generating circuit includes a high-voltage charging power supply, which is connected to one end of the two isolation ball gaps through two high-voltage pulse generators, and is connected to one electrode of the two-electrode gas gap through the two isolation ball gaps.

[0013] Furthermore, the high-voltage pulse generator is a pulse transformer or a Marx generator. The Marx generator charges each stage through a high-voltage charging power supply. Both ends of the first-stage high-voltage capacitor and the first-stage charging resistor are connected in parallel with the three-electrode spherical gap, and the switches of the subsequent stages of the circuit are two-electrode spherical gaps.

[0014] Furthermore, the two outputs of the signal generator are respectively connected to the input ends of two low-voltage pulse generating circuits, and the output ends of the two low-voltage pulse generating circuits are connected to the high-voltage pulse generator via the needle electrodes of the three-electrode spherical gap.

[0015] Furthermore, by adjusting the time intervals of the two outputs of the signal generator, the time interval of the output nanosecond high-voltage pulses can be continuously adjusted within 10 μs to 1 s.

[0016] Furthermore, one end of the three-electrode spherical gap is a stainless steel sphere, which is connected to the input end of the high-voltage pulse generator, and the other end of the three-electrode spherical gap is a stainless steel hemisphere, which is grounded. A trigger pin is provided in the middle of the hemisphere, which is connected to the output end of the low-voltage pulse generating circuit.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] The present invention discloses a gas switch insulation recovery characteristic test device. Based on the improved double pulse method, an experimental platform is established to equivalently measure the insulation recovery degree of the gas switch gap in the FLTD after self-breakdown. The present invention uses a low-voltage large-capacity energy storage capacitor to equivalently simulate the main energy storage capacitor in the FLTD, and uses a metal film resistor to equivalently simulate the charging isolation resistor between each branch in the FLTD, and together with the isolation magnetic core and the two-electrode gas gap, a discharge circuit is formed. The function of the isolation magnetic core is: when the nanosecond high-voltage pulse generated by the Marx generator acts on the high-voltage electrode of the gas gap, due to the high frequency of the voltage pulse, the impedance of the freewheeling branch is very high for the pulse, so that the switch can be smoothly broken down, and at the same time, the magnetic core is magnetized by the high-voltage pulse, and the inductance in the loop is very small for the freewheeling branch, and the freewheeling branch can be approximately regarded as a resistor-capacitor loop. When the gas gap is broken down, the freewheeling branch and the switch form a resistor-capacitor discharge loop, thereby simulating the situation that after the gas switch of a certain branch in the FLTD self-breaks down and discharges, the switch and the adjacent branch form a resistor-capacitor discharge loop. The energy storage capacitor is charged separately by a high-voltage DC power supply through a charging resistor. The resistance value of the isolation resistor and the charging voltage are adjustable. By changing the size of these two values, the working conditions of the gas switch in the FLTD after self-breakdown under different isolation resistances and different working coefficients can be equivalently explored. The dynamics of the gas gap after breakdown and the cut-off time can be observed through a coaxial shunt and an oscilloscope. For the gas gap, its withstand voltage cannot be restored immediately after the follow-up current is cut off. The insulation of the gas gap is fully restored only after the withstand voltage is fully restored.

[0019] Furthermore, the nanosecond pulse breakdown voltage of the gas gap between the two electrodes can be directly measured, and the insulation recovery characteristics of the gas gap between the two electrodes can be obtained by setting different interval times. And by connecting the isolation coil and the isolation resistor in series, the two pulse voltages and the long pulse current can be isolated, which can effectively ensure that the high-voltage probe can accurately measure the breakdown voltage and insulation recovery voltage of the gas gap between the two electrodes.

[0020] Furthermore, within the gas gap distance range of 2.5 to 10 mm, the breakdown voltage of the gas switch is stable, ensuring good repeatability of each output nanosecond pulse. The purpose of using high-voltage wires and annular ferrite cores for winding is to consider the high voltage gradient when the high-voltage nanosecond pulse acts on the isolation coil, and it is necessary to prevent insulation breakdown. The annular ferrite core has a high saturation magnetic induction intensity and BS curve, which helps to reduce the size of the isolation coil and improve the isolation effect of the trigger pulse.

[0021] Furthermore, the series coaxial shunt can avoid interference to the current measurement signal caused by nanosecond pulse discharge, thereby affecting the accuracy of the measured current signal.

[0022] Furthermore, the advantage of using two isolating ball gaps is that on the one hand, the nanosecond pulse voltage can be further steepened. At the same time, when the two nanosecond pulses act one after the other, the isolating ball gap can avoid the influence of the nanosecond pulse formed first on the nanosecond pulse device generated later, and ensure that the nanosecond pulse formed later only acts on the gas gap between the two electrodes, ensuring that the trigger pulse is accurate and reliable.

[0023] Furthermore, the advantage of using a pulse transformer and a Marx generator is that high-voltage pulses of more than one hundred nanoseconds can be obtained. Since the double-pulse method for studying the insulation recovery characteristics of switches generally requires a fast switch breakdown process, which does not affect the insulation recovery time of the gas gap, it helps to obtain accurate insulation recovery characteristics of the gas gap.

[0024] Furthermore, the two outputs of the signal generator are respectively connected to the inputs of the two low-voltage pulse generating circuits, and the outputs of the two low-voltage pulse generating circuits are connected to the high-voltage pulse generator via the needle electrodes of the three-electrode spherical gap, which helps to achieve precise control of the timing of nanosecond pulse generation.

[0025] Furthermore, the insulation recovery of the gas gap is basically completed within the time range of 10 μs to 1 s, and conducting insulation recovery characteristic testing within this time range is helpful to obtain complete insulation recovery characteristics of the gas gap.

[0026] To sum up, in order to address the deficiency that the current double-pulse method cannot measure the insulation recovery of a gas gap in the presence of a continuous current, the present invention innovatively proposes a method of increasing isolation and long pulse current, which, on the one hand, realizes the test of the insulation recovery characteristics of the gas gap, and on the other hand, the coupled long pulse current can equivalently simulate the insulation recovery process of the switch in the presence of a continuous current, thereby simulating the insulation recovery process currently existing in the FLTD drive source and other gas switches, and realizing accurate research on the insulation recovery process of the gas switch, which is helpful to promote further in-depth research on the insulation recovery characteristics of the switch.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the entire experimental device of the present invention;

[0029] Figure 2 In the present invention, the energy storage capacitor charging voltage is 200V, 300V, 400V, the isolation resistance is 133Ω, and the gas gap pressure between the two electrodes is at atmospheric pressure.

[0030] Figure 3 The voltage recovery curve of the gas gap between the two electrodes under atmospheric pressure when the charging voltage of the energy storage capacitor is 200V, 300V, and 400V and the isolation resistance is 133Ω.

[0031] Among them: 1. Two-electrode gas gap; 2. Isolation coil; 3. Isolation resistor; 4. Energy storage capacitor; 5. Charging resistor; 6. High-voltage DC power supply; 7. Gas valve; 8. Gas cylinder; 9. Signal generator; 10. Oscilloscope; 11. High-voltage probe; 12. Coaxial shunt; 13. Isolation ball gap; 14. High-voltage pulse generator; 15. Three-electrode ball gap; 16. Low-voltage pulse generating circuit; 17. High-voltage charging power supply. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0036] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0037] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0038] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0039] The present invention provides a gas switch insulation recovery characteristic test device, which uses a storage capacitor connected in series with an isolation resistor and an isolation core coil, connected to one end of the gas gap between two electrodes, and the other electrode of the gas gap between the two electrodes is grounded to form a discharge freewheeling circuit. The double nanosecond pulse generation circuit is composed of two completely identical pulse transformers or Marx, and the timing of outputting double nanosecond pulses is controlled by a signal generator and a low-voltage pulse generation circuit. The two pulse output ends are connected to the high-voltage end of the gas gap between the two electrodes through two isolation ball gaps. The first nanosecond pulse causes the gas gap to break down, and the breakdown voltage is U b1 , the electric energy in the energy storage capacitor is released through the freewheeling circuit; the time interval of the second nanosecond pulse acting on the gas gap is adjusted by using the signal generator, and the breakdown voltage of the second nanosecond pulse acting on the gas gap is U b2 , U b2 / U b1 It reflects the degree of insulation recovery after the gas gap is broken down in the presence of continuous current. By changing the isolation resistance and the charging voltage of the energy storage capacitor, the insulation recovery of the gas gap under different continuous current conditions can be explored.

[0040] See also Figure 1 The present invention provides a gas switch insulation recovery characteristic test experimental device, including a follow-up discharge circuit, a dual nanosecond pulse generating circuit and a dual nanosecond pulse timing control circuit; one end of the follow-up discharge circuit is connected to a gas cylinder 8 via a gas valve 7, and the other end is connected to the dual nanosecond pulse generating circuit, the dual nanosecond pulse timing control circuit is connected to the dual nanosecond pulse generating circuit, and the dual nanosecond pulse generating circuit controls the timing of outputting the dual nanosecond pulses through a signal generator 9 and a low-voltage pulse generating circuit 16.

[0041] The freewheeling discharge circuit includes a two-electrode gas gap 1, an isolation coil 2, an isolation resistor 3, an energy storage capacitor 4, a charging resistor 5 and a high-voltage DC power supply 6; the high-voltage end of the two-electrode gas gap 1 is divided into two paths, one path is connected to an oscilloscope 10 via a high-voltage probe 11, and the other path is connected to an isolation ball gap 13 of a dual nanosecond pulse generating circuit. The two-electrode gas gap 1, the isolation coil 2, the isolation resistor 3, and the energy storage capacitor 4 are connected in series to form a discharge circuit, the isolation resistor 3 and the energy storage capacitor 4 are connected in parallel with one end of the charging resistor 5, and the other end of the charging resistor 5 is respectively connected to the two-electrode gas gap 1 and the high-voltage probe 11.

[0042] Specifically, the isolation coil 3 is wound by a high-voltage wire and a toroidal ferrite core. For nanosecond pulses, it is in a high-impedance state. After the nanosecond pulse magnetizes the core, it is in a low-impedance state for freewheeling, and does not affect the freewheeling of the discharge circuit.

[0043] Specifically, the energy storage capacitor 4 is charged separately by the high-voltage DC power supply 6 through the charging resistor 5 .

[0044] Specifically, the gas gap 1 between the two electrodes is composed of a sealed insulating shell and two stainless steel metal electrodes, and the distance between the two stainless steel metal electrodes is 2.5-10 mm. The air hole on the insulating shell is connected to the gas cylinder 8 through the gas valve 7, so that the gas gap between the two electrodes can be ventilated and adjusted to work under different gas pressure conditions. The inductance value of the isolation coil 2 is greater than 500 μH.

[0045] Specifically, the size of the energy storage capacitor 4 is 309 μF, and the size of the charging voltage of the energy storage capacitor 4 and the size of the isolation resistor are adjusted to obtain freewheeling with different durations and amplitudes.

[0046] In this embodiment, the electrode distance in the gas gap 1 between the two electrodes is 2.5 mm, the air pressure in the insulating shell is set to atmospheric pressure, the resistance of the isolation resistor 3 is 133Ω, and the energy storage capacitor 4 is charged by a high-voltage DC power supply, and the charging voltages are set to 200V, 300V, and 400V respectively.

[0047] In this embodiment, the breakdown voltage of the two high-voltage pulses on the gas gap 1 between the two electrodes is U b1 , U b2 As long as the insulation of the switch is not fully restored, the second breakdown voltage U b2 Always less than the first breakdown voltage U b1 By changing the time interval Δt between the two pulses, U b2 / U b1 The recovery coefficient of the withstand voltage of the gas switch after breakdown is obtained.

[0048] In this embodiment, one end of the high voltage probe 11 is connected to the high voltage end of the gas gap 1 between the two electrodes, and the other end is connected to the oscilloscope 10 to obtain the pulse voltage waveform when the gas gap is broken down.

[0049] In this embodiment, the coaxial shunt 12 is connected in series between the energy storage capacitor 4 and the ground and connected to the oscilloscope 10 to obtain the current passing through the gas gap when the subsequent flow branch RC discharges after the gas gap discharges.

[0050] The dual nanosecond pulse generating circuit includes a high-voltage charging power supply 17, two high-voltage pulse generators 14 and two isolation ball gaps 13; one end of the two isolation ball gaps 13 is connected to the two electrode gas gaps 1, and the other end is connected to the high-voltage charging power supply 17 via the two high-voltage pulse generators 14.

[0051] Specifically, the high-voltage pulse generator 14 adopts a 6-stage Marx generator, each stage of the circuit is connected in series with a group of charging resistors at both ends of a 30kV.2000pF capacitor and then connected in parallel to both ends of a high-voltage charging power supply 17, the first stage high-voltage capacitor and the first stage charging resistor are connected in parallel to the three-electrode ball gap 15, and the switches of the subsequent stages of the circuit are two-electrode ball gaps. The outputs of the two-way Marx are connected to one end of the two-electrode gas gap 1 through two isolation ball gaps 13.

[0052] The two isolation ball gaps 13 are stainless steel spheres with a diameter of 19 mm. The two high-voltage pulse generators 14 are connected to one electrode of the two-electrode gas gap 1 through the two isolation ball gaps 13 to ensure that the two nanosecond high-voltage pulses do not interfere with each other when breaking through the gas gap.

[0053] Furthermore, the double nanosecond pulses generated by the high-voltage pulse generator 14 act successively on the high-voltage electrodes of the two-electrode gas gap 1. The first nanosecond high-voltage pulse causes the gas gap to break down, and the breakdown voltage is U b1 , the freewheeling circuit completes the discharge, and the electric energy in the energy storage capacitor 4 is released; by changing the time interval between the two pulses, the breakdown voltage of the second pulse high voltage pulse is U b2 , U b2 / U b1 It reflects the degree of insulation recovery after the gas gap is broken down in the presence of continuous current. Changing the time interval between two nanosecond high-voltage pulses can explore the specific value of insulation recovery after the gas gap is broken down.

[0054] The dual nanosecond pulse timing control circuit includes a signal generator 9, a low-voltage pulse generating circuit 16 and a three-electrode ball gap 15. One end of the two three-electrode ball gaps 15 is respectively connected to a high-voltage pulse generator 14, and the other end is electrically connected to the signal generator 9 via the low-voltage pulse generating circuit 16.

[0055] Furthermore, the two outputs of the signal generator 9 are respectively connected to the input ends of two low-voltage pulse generating circuits 16, and the output ends are connected to the needle electrodes of the three-electrode spherical gap 15 in the Marx generator. The trigger signal generator 9 generates two square wave pulse voltage signals with an amplitude of 5V and a pulse width of 10μs. The square wave pulse voltage signal is converted into a 10kV voltage pulse by the low-voltage pulse generator 16. This pulse causes the first-level three-electrode spherical gap 15 in the Marx to break down, and then the remaining spherical gaps of the Marx break down one after another, and a high-voltage pulse is output on the last-level capacitor.

[0056] The low-voltage pulse generating circuit 16 is composed of an optical fiber receiver, an optical fiber trigger and a transformer, which together constitute a dual nanosecond pulse timing control circuit to control the two high-voltage pulse generators 14 to generate dual nanosecond pulses with a continuously adjustable time interval of 1 μs to 1s.

[0057] The three-electrode ball gap 15 is a stainless steel sphere with a diameter of 19 mm. The two-way high-voltage pulse generator 14 is connected to one electrode of the two-electrode gas gap 1 through two isolation ball gaps 13.

[0058] Furthermore, by adjusting the time intervals of the two outputs of the signal generator 9, the time interval of the output nanosecond high-voltage pulses can be continuously adjusted to 10 μs to 1 s.

[0059] In this embodiment, a signal generator 9 is configured to generate two square wave pulse voltages with an amplitude of 5V and a pulse width of 10μs. The time intervals between the two pulses are respectively set to 2ms, 5ms, 8ms, 15ms, 30ms, 40ms, 60ms, 80ms, and 100ms after the freewheeling is cut off to obtain the withstand voltage recovery degree of the gas gap 1 between the two electrodes at different times after discharge.

[0060] In this embodiment, the 30kV.2000pF high voltage capacitors in the two Marx generators are charged to 9kV, and the charging resistor in the Marx is 1MΩ.

[0061] In this embodiment, the high-voltage pulse generator 14 generates two 50kV high-voltage negative pulses at a certain time interval to act on the high-voltage electrodes of the two-electrode gas gap 1 in the gas gap discharge circuit with freewheeling. The first high-voltage pulse causes the gas gap to break down, and the RC freewheeling branch and the gas gap form a loop for discharge. After the discharge is completed, the gas gap is shut off, and the second high-voltage pulse causes the gas gap to break down again, and the amplitude of the breakdown reflects the degree of insulation recovery of the gas gap at this moment.

[0062] The double pulse method can be used to measure the insulation recovery of the switch after the spark channel is extinguished. The working principle of the double pulse method is:

[0063] Two identical high-voltage pulses are applied to the switch to be tested at different time intervals and cause it to break down, resulting in two breakdown voltages U b1 , U b2 As long as the insulation of the switch is not fully restored, the second breakdown voltage U b2 Always less than the first breakdown voltage U b1 By changing the time interval between the two pulses, U b2 / U b1 The recovery coefficient of the gas switch's withstand voltage after breakdown can be obtained.

[0064] See also Figure 2 , is the continuous current waveform of the gas gap between the two electrodes observed on the oscilloscope 16. Figure 2It can be seen that the freewheeling peak values ​​are 1.3A, 2.2A, and 2.9A respectively when the charging voltage of the energy storage capacitor 4 is 200V, 300V, and 400V, and the freewheeling maintenance time is 34.7ms, 45.2ms, and 59.6ms respectively. Under three different charging voltages, the higher the voltage, the greater the freewheeling peak value, and the current value at the time of cutoff is basically close. The freewheeling will be maintained for a longer time under the condition of high voltage.

[0065] See also Figure 3 , is the withstand voltage recovery curve of the gas gap 1 between the two electrodes after the continuous current is cut off. Figure 3 It can be seen that when the charging voltage of the energy storage capacitor 4 is 200V, 300V, and 400V, the time taken for the withstand voltage of the gas gap to recover to 80% is 60ms, 135ms, and 150ms, respectively.

[0066] In summary, the present invention provides a gas switch insulation recovery characteristic test device, which uses two identical high-voltage generators to generate two continuously controllable dual high-voltage pulses with a time interval of 10μs to 1s through a signal generator, a low-voltage pulse generator, and a three-electrode ball gap switch in the high-voltage generator. The breakdown voltage can be measured by a high-voltage probe and an oscilloscope; thus, the insulation recovery of the gas switch gap in the FLTD under the influence of other branches after self-breakdown can be completely equivalently obtained. This is helpful in selecting key parameters such as suitable gas switch working pressure, charging isolation resistance, etc. in actual engineering.

[0067] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A gas switch insulation recovery characteristic test device, characterized in that: The invention comprises a dual nanosecond pulse timing control circuit, wherein the input end of the dual nanosecond pulse timing control circuit is connected to a signal generator (9), and the output end is connected to the high voltage end of the two-electrode gas gap (1) in the freewheeling discharge circuit through two isolation ball gaps (13). The timing of the dual nanosecond pulses is output to the freewheeling discharge circuit through the signal generator (9), the first nanosecond pulse is used to break down the gas gap, and the electric energy is released through the freewheeling circuit; the second nanosecond pulse acts on the gas gap, and the freewheeling discharge circuit is connected to an oscilloscope (10) through a high voltage probe (11). The high voltage end of the two-electrode gas gap (1) is divided into two paths, one path is connected to the oscilloscope (10) via a high voltage probe (11), and the other path is connected to the isolation ball gap (13). The two-electrode gas gap (1), the isolation coil (2), the isolation resistor (3) and the energy storage capacitor (4) are connected in series to form a discharge circuit. The isolation resistor (3) and the energy storage capacitor (4) are connected in parallel with one end of a charging resistor (5). The other end of the charging resistor (5) is connected to the two-electrode gas gap (1) and the high voltage probe (11) respectively via a high voltage DC power supply (6).

2. The gas switch insulation recovery characteristic test device according to claim 1 is characterized in that: The two-electrode gas gap (1) is composed of a sealed insulating shell and two stainless steel metal electrodes, the distance between the two stainless steel metal electrodes is 2.5~10mm, and the isolation coil (2) is wound by a high-voltage wire and a ring ferrite core.

3. The gas switch insulation recovery characteristic test device according to claim 2 is characterized in that: The inductance of the isolation coil (2) is greater than 500 μH.

4. The gas switch insulation recovery characteristic test device according to claim 1, characterized in that: A coaxial shunt (12) is connected in series between the energy storage capacitor (4) and the ground wire, and the coaxial shunt (12) is connected to the oscilloscope (10).

5. The gas switch insulation recovery characteristic test device according to claim 1, characterized in that: The dual nanosecond pulse generating circuit comprises a high-voltage charging power supply (17), wherein the high-voltage charging power supply (17) is connected to one end of two isolation ball gaps (13) via two high-voltage pulse generators (14), and is connected to one electrode of the two-electrode gas gap (1) via the two isolation ball gaps (13).

6. The gas switch insulation recovery characteristic test device according to claim 5, characterized in that: The high-voltage pulse generator (14) is a pulse transformer or a Marx generator. The Marx generator charges each stage via a high-voltage charging power supply (17). Both ends of the first-stage high-voltage capacitor and the first-stage charging resistor are connected in parallel with the three-electrode spherical gap (15). The switches of the subsequent stages of the circuit are two-electrode spherical gaps.

7. The gas switch insulation recovery characteristic test device according to claim 5, characterized in that: The two outputs of the signal generator (9) are respectively connected to the input ends of two low-voltage pulse generating circuits (16), and the output ends of the two low-voltage pulse generating circuits (16) are connected to the high-voltage pulse generator (14) via the needle electrodes of the three-electrode spherical gap (15).

8. The gas switch insulation recovery characteristic test device according to claim 7, characterized in that: By adjusting the time intervals of the two outputs of the signal generator (9), the time interval of the output nanosecond high-voltage pulses can be continuously adjusted within a range of 10 μs to 1 s.

9. The gas switch insulation recovery characteristic test device according to claim 7, characterized in that: One end of the three-electrode spherical gap (15) is a stainless steel sphere connected to the input end of the high-voltage pulse generator (14); the other end of the three-electrode spherical gap (15) is a stainless steel hemisphere connected to the ground; a trigger pin is provided in the middle of the hemisphere and connected to the output end of the low-voltage pulse generating circuit (16).

Images