CN107422239A - The more dash current discharge test device and methods of soil - Google Patents

Abstract

The invention discloses a soil multi-impulse current discharge test device and method, and belongs to the technical field of electric power system grounding characteristic tests. The device of the invention mainly includes the main body capacitor of the multi-impulse current generator, the control system of the multi-impulse current generator, the discharge ball gap group, the isolation ball gap, the delay controller, the analog grounding sandbox, the core-through current sensor, and the impulse voltage divider device, broadband digital oscilloscope or the like; the inventive method is to carry out the soil multiple impulse current discharge test on the basis of the inventive device. The invention can realize independently controllable waveform parameters and continuously adjustable multi-impact current waveform output, and can be widely used in the research on the discharge characteristics of the grounding system under the action of multiple impulse currents, and the development and implementation of other lightning multi-impact simulation experiments. observe. The invention has the output function of multiple impulse currents with adjustable time intervals, which can be more suitable for actual lightning conditions.

Description

Soil multi-impulse current discharge test device and method

technical field

The invention relates to the technical field of electric power system grounding characteristic test, in particular to a soil multi-impact current discharge test device and a method thereof.

Background technique

The impulse discharge characteristic of the grounding system is one of the important factors to ensure the safe and reliable operation of the power system. It is particularly important to study the impulse discharge characteristics of the grounding system and the soil medium. Using the impulse current generator to simulate the actual lightning and other impulse sources is one of the important means to study the characteristics of soil impulse discharge.

Existing studies have shown that lightning has the characteristics of one breakdown and multiple discharges. A lightning process usually includes the first discharge and multiple subsequent return strikes. The average number of return strikes is 3-5 times, and the time interval between two return strikes is several milliseconds. Between hundreds of milliseconds, the average time interval is 60ms.

At present, in the study of the impact characteristics of the grounding system, the single impulse current is used as the excitation source. The single impulse current can only simulate the first discharge of lightning, and cannot consider the effect of subsequent strikes. The soil is composed of soil particles, air in the particle gap, The composite medium composed of water and other substances will change the dielectric properties of the soil and the properties of the substances in the soil medium under the action of a large impact current, and the change of the material properties cannot be completely completed within milliseconds. Therefore, the soil discharge characteristics under the action of multiple impulse currents are different from those under the action of single impulse currents. The development of soil multi-impulse current generator can realize the simulation experiment of lightning multi-impact. Therefore, the design and development of multi-impulse current generators is of great significance for the study of soil multi-impulse discharge characteristics.

Contents of the invention

The purpose of the present invention is to propose a soil multi-impact current discharge test device and method; the device can realize independent control of waveform parameters, multi-impact current waveform output with continuously adjustable time intervals of multiple impulse currents, and is more suitable for actual lightning conditions.

The purpose of the present invention is achieved through the following technical solutions:

The soil multi-impact current discharge test device provided by the present invention includes at least two sets of independently controllable single impulse current generators; each set of single impulse current generators is respectively connected with a time delay control system; the time delay control system is used It is used to control the charging and discharging time of the single impulse current generator, so as to be suitable for each single impulse current generator to realize the output of multiple impulse currents in sequence.

Further, each set of single impulse current generator includes a charging control system, an impulse discharge main capacitor group, an electric discharge ball gap group, a wave modulation inductor, an isolation ball gap, and a wave modulation resistor;

The impact discharge main capacitor group is connected in parallel to the output end of the charging control system; one end of the impact discharge main capacitor group is connected to one end of the electric discharge ball gap group; the other end of the electric discharge ball gap group is sequentially connected to the wave modulation inductor and wave modulation Resistor connection; the other end of the wave modulation resistor is connected to the wave modulation resistance of another set of single impulse current generator through the isolation ball gap; and the wave modulation resistance is used as an output port; the other end of the shock discharge main capacitor group One end is connected to the impulse discharge main capacitor group of another set of single impulse current generator, and the other end of the impulse discharge main capacitor group is used as an output port;

The time delay control system is respectively connected with the electric discharge ball gap group; the time delay control system is used to control the charging and discharging time of the single impulse current generator, so as to be suitable for each single impulse current generator to realize the output of multiple impulse currents in sequence .

Further, the charging control system includes a voltage regulator, a step-up transformer, a silicon stack and a protection resistor;

The inlet terminal of the voltage regulator is connected to the power supply voltage; the outlet terminal of the voltage regulator is connected to the primary side of the step-up transformer; the secondary side of the step-up transformer is connected to the silicon stack; the silicon stack is connected to the protection resistor ; The protection resistor is connected with the electric discharge ball gap group.

Further, the surge discharge main capacitor group includes multi-stage parallel capacitors; the output end of the silicon stack is connected to the surge discharge main capacitor group through a charging resistor, and is used to charge the surge discharge main capacitor group; the surge discharge main capacitor The other end of the group is connected to the isolation resistor and the electric discharge ball gap group in turn; the common connection end of the isolation resistor and the electric discharge ball gap group is connected to the other end of the capacitor in turn; the last stage of the isolation resistor and the electric discharge ball gap group The common connection terminal is sequentially connected with the wave-modulating inductor and the wave-modulating resistor for outputting the surge current waveform.

Further, it also includes a soil sample and data acquisition system; the soil sample and data acquisition system includes a high-precision digital oscilloscope, a core-through current sensor, a metal electrode, a sandbox, and an impulse voltage divider;

After the output port of the single impulse current generator outputs the impulse current, it is introduced into the soil sample placed in the sandbox through a conductive cable and a metal electrode; The cable is connected to a high-precision digital oscilloscope for collecting current waveforms; the terminal voltage of the metal electrode is connected to the high-voltage end of the impulse voltage divider through a wire, and the signal output end of the impulse voltage divider is connected through a coaxial shielded cable A high-precision digital oscilloscope is used to acquire voltage waveforms.

Further, the time delay control system is connected to the spark triggers of each electric discharge ball gap group respectively via optical fiber.

At the same time, a soil multi-impulse current discharge test method is also provided, including the following steps:

(1) determine test waveform parameter and soil sample parameter; Described waveform parameter comprises the time interval between waveform head wave tail time and amplitude and many shock current waves;

(2) Connect the test circuit; the output ends of the two sets of impulse current generators are connected to the cable through the copper tape, connected to the metal electrode as the high-voltage end of the soil discharge test, and buried in the soil of the sandbox. The copper clad in the box is connected to the grounding wire as the grounding terminal; the core-through current sensor is sleeved on the cable, and the signal is transmitted to the digital oscilloscope with a coaxial shielded cable to collect the current waveform; the metal electrode terminal is connected to the Impulse voltage divider, and use coaxial shielded cable to send the signal to the digital oscilloscope to collect the voltage waveform;

(3) Multi-inrush current waveform output pre-commissioning; set the preset voltage for the impulse current generator respectively; install the corresponding preset voltage to adjust the ball gap distance of the discharge ball gap group, and then perform the charge and discharge test;

(4) Connect the soil sample and data acquisition system to conduct multi-impact discharge test.

Further, the data acquisition system performs data acquisition in the following manner:

Obtain the current waveform signal in the discharge circuit through the core-through current sensor looped on the cable, and transmit the current waveform signal to the digital oscilloscope through the coaxial shielded cable for current waveform acquisition;

Obtain the voltage waveform on the metal electrode through the impulse voltage divider connected to the discharge high voltage end, and transmit the signal to the digital oscilloscope through the coaxial shielded cable for voltage waveform acquisition;

Export and store the voltage and current waveforms in the digital oscilloscope, and obtain the voltage and current peak values and the corresponding voltage and current values at each moment.

Further, the multi-inrush current waveform output pre-commissioning is specifically implemented according to the following steps:

①First set the preset voltage for the first impulse current generator, automatically adjust the ball gap distance of the discharge ball gap group according to the corresponding voltage, and then charge the capacitor group. After the charging is completed, send the discharge trigger signal to the discharge ball gap group to start Discharge test; if the discharge fails, fine-tune the ball gap distance of the discharge ball gap group until normal discharge;

②Set the preset voltage for the second impulse current generator, adjust the ball gap distance of the discharge ball gap group according to the corresponding voltage, isolate the ball gap short circuit, and then charge the capacitor group. After the charging is completed, it will be sent to the discharge ball gap group Discharge trigger signal for discharge test; if the discharge fails, fine-tune the ball gap spacing of the discharge ball gap group until normal discharge;

Adjust the distance between the isolation ball gaps according to the corresponding voltage, and then re-do the above charge and discharge test; if the discharge fails, fine-tune the distance between the isolation ball gaps until the normal discharge;

③ Finally, set the time interval.

Owing to adopting above-mentioned technical scheme, the present invention has following advantage:

The soil multi-impulse current discharge test device provided by the present invention realizes independently controllable waveform parameters and continuously adjustable multi-impulse current time interval multi-inrush current waveform output, and can be widely used in research on the discharge characteristics of grounding systems under the action of multiple impulse currents, and other Development and observation of lightning multi-shock simulation experiment. The invention has the output function of multi-impact current with adjustable time interval, which can be more suitable for the actual lightning situation, and mainly has the following technical effects:

(1) The multi-inrush current generating device in the present invention can output multi-inrush current waves with continuously adjustable time intervals between waveforms, can simulate the situation of one-time breakdown and multiple discharges in the actual lightning situation, and the device has a large capacity, which can realize High amplitude and high current output for soil samples. It is more suitable for the actual soil impact discharge situation.

(2) The delay control system in the present invention has high control precision and a large controllable range. It can ensure effective time control of the short process of impulse discharge, and generate multiple impulse current waveforms that meet the test requirements.

(3) The devices of the present invention are all indoor test platforms, and can repeatedly carry out experimental research on simulating actual lightning strike conditions indoors. It has the advantages of simple operation, high controllability and low cost.

(4) The digital oscilloscope of the device of the present invention adopts a combination of an independent storage battery and an inverter or an offline UPS power supply, which can effectively prevent the surge current generator from being discharged, and the potential of the laboratory ground grid rises sharply and damages the digital oscilloscope, core-through type Occurrence of phenomena in measuring equipment such as current sensors.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention may be realized and attained by the following specification.

Description of drawings

The accompanying drawings of the present invention are described as follows.

Fig. 1 is a principle wiring diagram of the multi-inrush current discharge device of the present invention.

FIG. 2 is a schematic structural diagram of the multi-inrush current discharge device in FIG. 1 .

Figure 3 is a schematic diagram of the simulated grounding sandbox and data acquisition system.

Fig. 4 is a logic schematic diagram of multiple impulse current discharge triggering.

In the figure: 1 multiple impulse current generating device, 2, 3 voltage regulator, 4, 5 step-up transformer, 6, 7 silicon stack, 8, 9 protection water resistance, 10, 11 pulse capacitor bank, 12, 13 electric discharge ball Gap group, 14, 15 wave modulation inductor, 16, 17 wave modulation resistor, 18 time delay control system, 19 isolation ball gap, 20 soil sample and data acquisition system, 21 high precision digital oscilloscope, 22 core-through current sensor, 23 Metal electrode, 24 sandbox, 25 impulse voltage divider, 26,27 charging resistor, 28,29 isolation resistor, 30 intelligent control system

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

Example 1

As shown in the figure, the soil multi-impulse current discharge test device provided in this embodiment can be used to simulate multiple actual lightning strikes and discharges. , to realize the multi-impact discharge test on soil; through the multi-gap group isolation technology and high-precision time-delay control technology, a multi-impact high-current output is provided for the soil sample load, and the time interval between multiple impulse currents is continuously controllable. Fill in the gaps in the field of soil multi-shock discharge research.

This device mainly includes impact discharge main capacitor group, discharge ball gap group, isolation ball gap, time delay control system, charging control system, wave modulation resistor inductance, core-through current sensor, high-precision digital oscilloscope, etc.

The main part is two sets of independent and controllable single impulse current generators. The trigger discharge time of the two sets of impulse current generators is controlled by the charging control system, time delay control system and connecting optical fiber, so as to realize the output of multiple impulse currents.

The two sets of single impulse current generators in this embodiment are respectively the first single impulse current generator and the single impulse current generator; they can form the first and second impulse discharge circuits respectively.

The main capacitor group of the impact discharge, the charging control system, and the wave-modulating resistor and inductor are customized products. The optional range of the rated parameters of each capacitor is 50~150kV/2~5μF, 1-5 capacitors form a group, and there are 2-10 capacitors in two groups. The charging control system is mainly composed of computer control software, transformer, and PLC control parts. The resistance value range of the modulation resistor is 10Ω～5000Ω, and the modulation inductance is 0～200μH.

The discharge ball gap group is a customized product. The specific specification is electric 1-5 discharge ball gap groups, each level of ball gap corresponds to a capacitor, the capacitor groups are connected in parallel during charging, and each level of ball gap isolates a capacitor voltage. The discharge adopts the capacitor series connection method, and the electric spark touches the multi-level ball gap cascade discharge.

An isolation ball gap is provided in the second impact discharge circuit, and the isolation ball gap is a customized product, so as to isolate the potential rise generated by the first impact discharge and avoid linkage discharge. The distance between the isolation ball gaps is continuously adjustable between 0 and 150mm. The working model has two options: natural discharge and electric spark triggered discharge.

The delay control system is a customized product. The controllable range of the time delay is 0-5000ms, and the control precision of the time delay controller is at the nanosecond level. Taking into account the linkage delay between various devices, the microsecond-level adjustable accuracy of the multi-impact current wave time interval can be realized.

Example 2

The multi-impulse current generating device provided in this embodiment is a customized product, which can work in two modes of single-impulse discharge and multiple-impact discharge. It can instantaneously output double-exponential current waves with adjustable amplitude from 1 to 300 kA, wave front time from 1 to 50 μs, and wave tail time from 10 to 1000. The time interval between multiple shock current waves is continuously adjustable within the range of 0-5000ms. The main part of the multi-impulse current generator is two sets of independently controllable single-impulse current generators. The trigger discharge time of the two sets of impulse current generators is controlled by the charging control system, the delay control system and the connecting optical fiber, so as to realize the multi-impact current generator. Output. Each set of single impulse current generator mainly includes: voltage regulator, step-up transformer, silicon stack, wave-modulating resistor, wave-modulating inductance, pulse capacitor bank, electric discharge ball-gap bank. The intelligent control system is connected to the voltage regulator through an optical fiber. The input end of the voltage regulator is connected to the 380V power frequency power supply through a wire, and the outlet end of the voltage regulator is connected to the primary side of the step-up transformer through a wire; the secondary side of the step-up transformer Connect to the silicon stack with a wire; charge the capacitor bank through the silicon stack. The capacitor group of each impulse current generator is composed of 1-5 capacitors. After charging, it can be discharged through the discharge ball gap, wave-modulating inductor, and wave-modulating resistor to output the impulse current waveform.

The discharge ball gap group is a customized product. The control system is connected to the discharge ball gap group through optical fiber, and intelligently adjusts the ball gap distance according to the set voltage level to ensure the normal output of the impulse current. When the capacitor is charged, the charging circuit works, and the capacitor banks are connected in parallel for charging. Each level of ball gap corresponds to a capacitor, and the isolation resistor is used to isolate the voltage on one capacitor. After the charging is completed, the control system sends a trigger signal to the spark trigger of the discharge ball gap group through the optical fiber to generate an electric spark between the ball gaps. The discharge ball gap group is triggered by the spark ignition. When the capacitor is discharged, the discharge circuit works, and the capacitor group The series connection method is used to trigger the multi-stage ball gap cascade discharge with electric sparks. The capacitor group is discharged through the wave-modulating inductor and the wave-modulating resistor, so as to output the shock current wave of the set parameters.

The time delay control system of the multiple impulse current generator is a customized product. After the multiple impulse current waveforms are output, they are introduced into the soil sample through cables and metal electrodes. Take fine sandy soil as the soil sample and place it in a sandbox of insulating material with a side length of 200-1000 mm. The bottom and sides of the sandbox are covered with copper sheets and grounded. Realize the discharge of multiple impulse currents to the soil.

Example 3

As shown in Figures 1 to 3, the soil multi-impulse current discharge test device is mainly composed of the impact discharge main capacitor group 10-11, the discharge ball gap group 12-13, the isolation ball gap 19, the time delay control system 18, and the charging control system 2-9, wave-modulating inductance 14-15, wave-modulating resistor 16-17, core-through current sensor 22, impulse voltage divider 25 and high-precision digital oscilloscope 21, etc.

The main part of the multiple impulse current generating device 1 is two sets of independently controllable single impulse current generators, and the trigger discharge of the two sets of impulse current generators is controlled by the charging control system 2-9, the time delay control system 18 and the connecting optical fiber. Time, so as to realize the output of multi-inrush current. Each set of single impulse current generator mainly includes: intelligent control system, voltage regulator 2~3, step-up transformer 4~5, silicon stack 6~7, wave-modulating resistor 16-17, wave-modulating inductor 14-15, pulse capacitor Groups 10-11, electromotive discharge ball gap groups 12-13. The intelligent control system is connected with voltage regulators 2~3 through optical fiber, the incoming line terminals of voltage regulators 2~3 are connected with 380V power frequency power supply through wires, and the outgoing line terminals of voltage regulators 2~3 are connected with step-up transformers 4~5 The primary sides are connected by wires; the secondary sides of the step-up transformers 4-5 are connected with the silicon stacks 6-7 by wires; the capacitor groups 10-11 are charged through the silicon stacks 6-7 and the charging resistors 26-27. The capacitor group of each impulse current generator is composed of 1-5 capacitors. After charging, it can be discharged through the discharge ball gap group 12-13, the wave-modulating inductor 14-15, and the wave-modulating resistor 16-17, and the impulse current waveform is output.

The specific specifications of the discharge ball gap groups 12 to 13 are electric 5-stage discharge ball gap groups. The control system is connected to the discharge ball gap groups 12-13 via optical fiber, and intelligently adjusts the distance between the ball gaps according to the set voltage level to ensure the normal output of the impulse current. Each level of ball gap corresponds to a capacitor. When charging, the capacitor groups are connected in parallel, and each level of ball gap cooperates with isolation resistors 28-29 to isolate the voltage on one capacitor. After the charging is completed, the control system transmits trigger signals to the spark triggers of the discharge ball gap groups 12-13 via optical fibers to generate an electric spark between the ball gaps. Capacitors are connected in series to trigger 5-level ball gap cascade discharge with electric sparks. The capacitor groups 10-11 are discharged through the wave-modulating inductors 14-15 and the wave-modulating resistors 16-17, so as to output the impulse current wave with the set parameters.

The time delay control system 18 of the multi-impact current generator is connected to the spark triggers of the two sets of impulse discharge ball gap groups 12-13 respectively through optical fibers. The delay control system 18 has two working modes: autonomous triggering and detection triggering. When working in the autonomous trigger mode, when the trigger signal is sent to the delay control system 18, the delay control system 18 processes and outputs two signals to the two sets of discharge ball gap groups 12-13 respectively, and the two signals have the set A certain time delay is used to control the trigger discharge time of the two sets of discharge ball gap groups 12-13, so that the discharge has a time difference and realize the output of multiple impulse currents. When working in the detection trigger mode, when the trigger signal is sent to the delay control system 18, the delay control system 18 directly sends it to the first impact discharge ball gap group 12 to trigger discharge and detect the discharge situation. When the first impact discharge is successful , the delay control system 18 will receive the feedback signal, and start from this moment, and send a trigger signal to the second impact discharge ball gap group 13 after a specified time delay to realize the second impact discharge. The specific delay time can be written into the time delay control system 18 through computer software before discharging. The controllable range of the time delay is 0-5000ms, and the control accuracy of the time delay control system 18 is nanosecond level. Delay, so as to realize the output of multiple impulse currents at different time intervals with an accuracy of microseconds.

The main function of the isolation ball gap 19 is to isolate the influence of the potential rise caused by the first impulse discharge on the subsequent impulse discharge in the multi-impulse discharge process. The first shock discharge will generate an instantaneous potential rise on the soil sample, which will cause the voltage distortion at both ends of the ball gap of the second shock discharge and discharge at the same time as the first shock, and the time delay control will fail. Increasing the isolation ball gap can effectively solve this problem. The distance between the isolation ball gaps 19 is set to the isolation distance corresponding to the first impact output voltage, and has an adjustment range of -30 to +30 mm, so that it can isolate the influence of the potential rise on the soil sample without affecting the second Normal discharge of inrush current.

After the multiple impulse current waveforms are output, they are introduced into the soil sample through cables and metal electrodes 23 . Take fine sand as the soil sample and place it in a sandbox 24 made of insulating material with a side length of 200*200*200mm. The inner bottom and sides of the sandbox 24 are covered with copper sheets and grounded. A metal electrode 23 with a length of 100 mm is vertically placed in the center of the sandbox 24 . Realize the discharge of multiple impulse currents to the soil. The core-through current sensor 22 is looped on the conductive cable, and connected to the high-precision digital oscilloscope 21 through the coaxial shielded cable to collect the current waveform. The voltage at the metal electrode 23 terminal is connected to the high-voltage end of the impulse voltage divider 25 through wires, and the signal output end of the impulse voltage divider 25 is connected to a high-precision digital oscilloscope 21 through a coaxial shielded cable for collecting voltage waveforms.

The high-precision oscilloscope 21 adopts a commercially available module, 4 independent signal acquisition channels, a bandwidth of 50-200MHz, a real-time sampling rate of 0-2GSa/s, and a storage depth of 1k-24Mpts, which can ensure the accuracy and length of the collected signals. The power supply of the high-precision digital oscilloscope is a combined power supply of an independent storage battery and an inverter or an offline UPS power supply, which can not only improve the signal-to-noise ratio of the signal obtained by the digital oscilloscope, but also prevent the impact of large currents when the impulse current generator is discharged. The potential of the ground grid in the laboratory rises sharply and damages the digital oscilloscope.

The test sandbox 24 provided in this embodiment has a side length of 300*200*200mm and is made of insulating material. Sandbox 24 inner bottom surface and side are covered with copper sheet and grounded. A metal electrode 23 with a length of 100 mm is placed horizontally in the center of the sandbox 24 .

The test sandbox 24 provided in this embodiment has a side length of 1000*200*200mm and is made of insulating material. Sandbox 24 inner bottom surface and side are covered with copper sheet and grounded. A metal electrode 23 with a length of 800 mm is placed horizontally in the center of the sandbox 24 .

Example 4

This embodiment provides a soil multi-impact current discharge test method. Using this device, the soil multi-impact discharge is carried out through steps such as determining the waveform and soil parameters, connecting the test circuit, outputting the multi-impact current waveform pre-commissioning, performing a multi-impact discharge test, and collecting data. The specific scheme and pre-commissioning steps of the test are as follows:

(1) Determine the test waveform parameters and soil sample parameters

First, determine the test waveform parameters and soil sample parameters according to the test requirements and planning. Among them, the waveform parameters mainly include: the wave head and tail time of the first and second shock current waves, the shock current amplitude and the time interval between multiple shock currents; the soil sample parameters mainly include soil type, soil resistivity, sandbox and electrode size.

① Determine the wave head and tail time and amplitude. By adjusting the wave-modulating inductance 14-15 and the wave-modulating resistor 16-17 of the first impulse current generator and the second impulse current generator respectively, the wave head time and wave tail time of the two impulse current waveforms can be independently adjusted. Before adjusting the tuning inductors 14-15 and tuning resistors 16-17, their reference values can be determined by simulation software or calculation formulas. Adjusting the surge current wave amplitude by changing the charging voltage of the discharge capacitor group 10-11;

② Determine the time interval between multiple impulse current waves. Before charging starts, the time interval between multiple surge currents is set by writing the required time delay into the time delay control system 18 .

③ Determine the soil parameters. Determine the type of soil and the size of the sandbox 24 and the metal electrode 23 according to the test requirements. Adjust the soil resistivity by adjusting the water content and salt content of the soil. First, the soil sample is washed to remove the soluble salt components, and it is cleared several times until the salinity of the washing solution is close to 0; then the soil sample is dried to remove the moisture in the soil; finally, the preset quality of water and salt is added according to the test requirements, The salt is dissolved in water as NaCl crystals and added to the soil. The soil resistivity was then measured and recorded.

(2) Connect the test circuit

After the step (1) is completed, the test circuit wiring is carried out according to the device of the present invention. Connect the output ends of the two sets of impulse current generators to the cables through braided copper strips, connect them to the metal electrode 23 as the high-voltage end of the soil discharge test, and bury them in the soil of the sandbox 24. The sandbox 24 is covered with The copper skin is connected to the ground wire as the ground terminal. The core-through current sensor 22 is looped on the cable, and the coaxial shielded cable is used to transmit the signal to the digital oscilloscope 21 to collect the current waveform. Connect the end of the metal electrode 23 to the impulse voltage divider 25 with a metal wire, and use a coaxial shielded cable to send the signal to a digital oscilloscope 21 to collect the voltage waveform.

(3) Multi-inrush current waveform output pre-debugging

After step (2) is completed, it is necessary to carry out pre-commissioning on the inventive equipment to ensure the synchronization and normal triggering among the various equipment of the multi-inrush current generating device 1 before the test can be carried out.

①First set the preset voltage for the first impulse current generator, automatically adjust the ball gap distance of the discharge ball gap group 12 according to the corresponding voltage, then charge the capacitor group, and send the discharge trigger to the discharge ball gap group 12 after the charging is completed signal for a discharge test. If the discharge fails, fine-tune the distance between the ball gaps of the discharge ball gap group 12 until normal discharge;

②Set the preset voltage for the second impulse current generator, adjust the ball gap distance of the discharge ball gap group 13 according to the corresponding voltage according to the content of claim 4, short-circuit the isolation ball gap 19, and then charge the capacitor group, and wait for the charging to be completed Afterwards, a discharge trigger signal is sent to the discharge ball gap group 13 to perform a discharge test. If the discharge fails, fine-tune the distance between the ball gaps of the discharge ball gap group 13 until normal discharge. Thereafter, adjust the distance between the isolation ball gaps 19 according to the corresponding voltage according to the content of claim 5, and then carry out the above-mentioned charging and discharging test again. If the discharge fails, fine-tune the spacing between the isolation ball gaps 19 until normal discharge;

③ Finally, set the time interval. 4, the intelligent control system 30 first writes the preset time interval into the time delay control system 18. At this time, the time delay control system 18 calibrates the zero time, and immediately sends the discharge ball gap of the first impulse current generator Group 12 sends a trigger signal to trigger discharge; after a preset time delay, time delay control system 18 sends a trigger signal to discharge ball gap group 13 of the second impulse current generator to trigger discharge. Thus, the test multi-inrush current generating device 1 is fully operated, and the preset waveform is output.

(4) Conduct multi-impact discharge test

After completing step (3), carry out the soil multi-impact discharge test. In the case of only changing the time interval without changing the magnitude of the impulse current, the pre-commissioning described in step (3) may not be necessary. At this time, the distance between the ball gaps remains unchanged. Set the time interval on the operating platform of the control system and write it into the delay control system 18, and then click the "charge" button of the first and second impulse current generators to start charging respectively. After the charging is completed, click the "trigger" button, The ignition trigger devices of the discharge ball gap groups 12-13 will respectively trigger the two sets of discharge ball gap groups 12-13 to discharge according to the set time delay. The multi-impact current is injected into the ground through the soil sample, and a soil multi-impact discharge test is completed. After each test, the soil in the sandbox 24 was refurbished and restored, and each multi-impact discharge test was at least 2-5 minutes apart.

(5) Data collection

When performing step (4), the core-through current sensor 22 looped on the cable can monitor the current waveform in the discharge circuit, and transmit the signal to the digital oscilloscope 21 through the coaxial shielded cable to collect the current waveform. The impulse voltage divider 25 connected to the discharge high voltage end can monitor the voltage waveform on the metal electrode 23, and transmit the signal to the digital oscilloscope 21 through the coaxial shielded cable to collect the voltage waveform.

After completing step (4), the voltage and current waveforms in the digital oscilloscope 21 can be exported and stored, and the voltage and current peak values and corresponding voltage and current values at each moment can be obtained for subsequent data analysis.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the protection scope of the present invention.

Claims (9)

1. Soil multiple impulse current discharge test device is characterized in that: comprise at least two sets of independently controllable single impulse current generators; Described each cover single impulse current generator is connected with time delay control system respectively; Described time delay control The system is used to control the charging and discharging time of the single impulse current generator, so as to be suitable for each single impulse current generator to realize the output of multiple impulse currents in sequence. 2. The soil multi-impulse current discharge test device as claimed in claim 1, characterized in that: each set of single-impulse current generators includes a charge control system, an impact discharge main capacitor group, an electric discharge ball gap group, and a wave-modulating inductance , isolation ball gap and wave tuning resistor; The impact discharge main capacitor group is connected in parallel to the output end of the charging control system; one end of the impact discharge main capacitor group is connected to one end of the electric discharge ball gap group; the other end of the electric discharge ball gap group is sequentially connected to the wave modulation inductor and wave modulation Resistor connection; the other end of the wave modulation resistor is connected to the wave modulation resistance of another set of single impulse current generator through the isolation ball gap; and the wave modulation resistance is used as an output port; the other end of the shock discharge main capacitor group One end is connected to the impulse discharge main capacitor group of another set of single impulse current generator, and the other end of the impulse discharge main capacitor group is used as an output port; The time delay control system is respectively connected with the electric discharge ball gap group; the time delay control system is used to control the charging and discharging time of the single impulse current generator, so as to be suitable for each single impulse current generator to realize the output of multiple impulse currents in sequence . 3. The soil multi-impulse current discharge test device as claimed in claim 1, characterized in that: the charging control system includes a voltage regulator, a step-up transformer, a silicon stack and a protective resistor; The inlet terminal of the voltage regulator is connected to the power supply voltage; the outlet terminal of the voltage regulator is connected to the primary side of the step-up transformer; the secondary side of the step-up transformer is connected to the silicon stack; the silicon stack is connected to the protection resistor ; The protection resistor is connected with the electric discharge ball gap group. 4. soil multi-impulse current discharge test device as claimed in claim 2, is characterized in that: described impulse discharge main capacitance group comprises the capacitor of multistage parallel connection; connected to charge the impact discharge main capacitor group; the other end of the impact discharge main capacitor group is connected to the isolation resistor and the electric discharge ball gap group in turn; the common connection end of the isolation resistor and the electric discharge ball gap group is sequentially connected to the other The other end of the first-stage capacitor is connected; the last-stage isolation resistor and the common connection end of the electric discharge ball gap group are sequentially connected to the wave-modulating inductance and the wave-modulating resistor for outputting the surge current waveform. 5. soil multiple impulse current discharge test device as claimed in claim 1, is characterized in that: also comprise soil sample and data acquisition system; Described soil sample and data acquisition system comprise high-precision digital oscilloscope, core-through current sensor, Metal electrodes, sandboxes and surge voltage dividers; After the output port of the single impulse current generator outputs the impulse current, it is introduced into the soil sample placed in the sandbox through a conductive cable and a metal electrode; The cable is connected to a high-precision digital oscilloscope for collecting current waveforms; the terminal voltage of the metal electrode is connected to the high-voltage end of the impulse voltage divider through a wire, and the signal output end of the impulse voltage divider is connected through a coaxial shielded cable A high-precision digital oscilloscope is used to acquire voltage waveforms. 6. The soil multi-impulse current discharge test device according to claim 2, characterized in that: the time delay control system is connected to the spark triggers of each electric discharge ball gap group through optical fibers. 7. The test method for soil multi-impulse current discharge, characterized in that it comprises the following steps: (1) determine test waveform parameter and soil sample parameter; Described waveform parameter comprises the time interval between waveform head wave tail time and amplitude and many shock current waves; (2) Connect the test circuit; the output ends of the two sets of impulse current generators are connected to the cable through the copper tape, connected to the metal electrode as the high-voltage end of the soil discharge test, and buried in the soil of the sandbox. The copper clad in the box is connected to the grounding wire as the grounding terminal; the core-through current sensor is sleeved on the cable, and the signal is transmitted to the digital oscilloscope with a coaxial shielded cable to collect the current waveform; the metal electrode terminal is connected to the Impulse voltage divider, and use coaxial shielded cable to send the signal to the digital oscilloscope to collect the voltage waveform; (3) Multi-inrush current waveform output pre-commissioning; set preset voltages for the impulse current generators respectively; adjust the ball gap distance of the discharge ball gap group according to the corresponding preset voltage, and then conduct a charge and discharge test; (4) Connect the soil sample and data acquisition system to conduct multi-impact discharge test. 8. soil multi-impulse current discharge test method as claimed in claim 7, is characterized in that: described data acquisition system carries out data acquisition according to the following manner: Obtain the current waveform signal in the discharge circuit through the core-through current sensor looped on the cable, and transmit the current waveform signal to the digital oscilloscope through the coaxial shielded cable for current waveform acquisition; Obtain the voltage waveform on the metal electrode through the impulse voltage divider connected to the discharge high voltage end, and transmit the signal to the digital oscilloscope through the coaxial shielded cable for voltage waveform acquisition; Export and store the voltage and current waveforms in the digital oscilloscope, and obtain the voltage and current peak values and the corresponding voltage and current values at each moment. 9. The soil multi-impulse current discharge test method as claimed in claim 7, characterized in that: said multi-impulse current waveform output pre-commissioning is specifically implemented according to the following steps: ①First set the preset voltage for the first impulse current generator, automatically adjust the ball gap distance of the discharge ball gap group according to the corresponding voltage, and then charge the capacitor group. After the charging is completed, send the discharge trigger signal to the discharge ball gap group to start Discharge test; if the discharge fails, fine-tune the ball gap distance of the discharge ball gap group until normal discharge; ②Set the preset voltage for the second impulse current generator, adjust the ball gap distance of the discharge ball gap group according to the corresponding voltage, isolate the ball gap short circuit, and then charge the capacitor group. After the charging is completed, it will be sent to the discharge ball gap group Discharge trigger signal for discharge test; if the discharge fails, fine-tune the ball gap spacing of the discharge ball gap group until normal discharge; Adjust the distance between the isolation ball gaps according to the corresponding voltage, and then re-do the above charge and discharge test; if the discharge fails, fine-tune the distance between the isolation ball gaps until the normal discharge; ③ Finally, set the time interval.