CN115166134A - Long continuous current discharge simulation device with independently controllable current magnitude and duration - Google Patents

Abstract

The invention discloses a long continuous current discharge simulation device with independently controllable current magnitude and duration, which mainly comprises a high-voltage arc starting unit (1), a continuous discharge unit (2), a capacitance capacity control system (3), a charging voltage control system (4), a time-delay circuit-breaking system (5) and control software, wherein the capacitance capacity control system, the charging voltage control system, the time-delay circuit-breaking system and the control software are connected in the continuous discharge unit (2). The high-voltage arcing unit (1) of the device can ignite the electric arc instantly (dozens of microseconds), and then the continuous discharging unit (2) can maintain the electric arc for a long time (the electric arc current is 100-300 amperes, and the duration is 100-500 milliseconds). The capacitance capacity control system (3) and the charging voltage control system (4) of the device can control the discharge current; the time-delay circuit-breaking system (5) can control the discharge duration. The invention can independently control the current magnitude and the duration time in the simulation of long continuous current discharge, and is used for developing the research of igniting forest combustible by lightning stroke.

Description

Long continuous current discharge simulation device with independently controllable current magnitude and duration

Technical Field

The invention belongs to the technical field of fire safety, and particularly relates to a long continuous current discharge simulation device with independently controllable current magnitude and duration.

Background

Lightning strikes are an important natural cause of forest fires, and forest fires induced by lightning strikes are referred to as "lightning strikes". Although the number of lightning strikes is less than that of artificial fires, the lightning strikes are widely concerned because the lightning strikes tend to cause a very large fire area and economic loss.

Lightning strike discharges in nature mainly contain two basic forms: pulsed impulse current discharge and long continuous current discharge. The peak current value of the pulsed impulse current discharge is large (about tens to hundreds of kiloamperes), but the duration is extremely short (about hundreds of microseconds), and forest combustibles cannot be ignited generally. Long continuous current discharges close to dc discharges, with low current amplitudes (in the order of hundreds of amperes) but long durations (above 40 milliseconds), capable of transferring large amounts of charge, releasing large amounts of heat, generally considered as the main form of discharge for the ignition of forest combustibles.

At present, a lightning strike discharge simulation device in the market mainly simulates impulse impact current discharge in lightning strikes by mainly using impact voltage or impact current generation equipment, and is usually used for developing impact voltage tests of power overhead lines, aircraft composite materials and the like under the action of lightning shock waves and detecting the safety performance of the equipment or the materials. Although the voltage/current level of this kind of discharge simulation device is high (the amplitude can reach tens or hundreds of kilovolts/kiloamperes), the duration is only tens of microseconds, and the long continuous current discharge in lightning can not be simulated.

The existing simulation device for long continuous current discharge is used for simulating long continuous current discharge in lightning by high-voltage pulse discharge arc striking and then maintaining long-time discharge (dozens of milliseconds) by a large-capacity capacitor bank. However, the test device can only change the initial voltage of the capacitor bank, and cannot independently control the magnitude and duration of the discharge current. The initial voltage of the capacitor bank depends on the parameters of the discharge device, and the parameters of lightning in practice cannot be directly represented.

Therefore, in order to deeply research the ignition problem of forest lightning stroke fire and the influence of the lightning stroke current and the duration on the lightning stroke fire, it is very important to develop a set of long continuous current discharge simulation device with independently controllable current and duration. The discharge simulation device is not only suitable for the experimental research of forest lightning stroke fire, but also suitable for the research of long continuous current discharge impact on power lines, power equipment, airplanes, wooden buildings and the like.

Disclosure of Invention

In order to solve the technical problems, the invention provides the long continuous current discharge simulation device with independently controllable current magnitude and duration, and provides a test basis for researching the ignition problem of forest lightning stroke fire.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a long continuous current discharge simulation device with independently controllable current magnitude and duration comprises a high-voltage arc starting unit, a continuous discharge unit, a capacitance capacity control system, a charging voltage control system and a time-delay circuit breaking system; the capacitance capacity control system, the charging voltage control system and the time delay circuit breaking system are connected with the continuous discharging unit;

the high-voltage arc striking unit comprises an impulse voltage generator;

the continuous discharging unit comprises a capacitor bank and a direct current charging device for charging the capacitor bank; the capacitor bank is formed by connecting a plurality of sub-capacitor banks in parallel;

the capacitance capacity control system comprises a selection switch and a plurality of on-off switches a, wherein the selection switch is connected with the on-off switches a to control the on-off of the on-off switches a; the number of the on-off switches a is equal to that of the sub-capacitor groups in the continuous discharge unit, and the on-off switches a are connected to the parallel branch where the sub-capacitor groups are located;

the charging voltage control system comprises a voltage sensor, a voltage comparison microprocessor and an on-off switch b; the voltage sensor is connected to two ends of a capacitor bank in the continuous discharging unit, and the on-off switch b is connected between the capacitor bank and the direct current charging device;

the voltage sensor and the on-off switch b are connected with the voltage comparison microprocessor;

the time-delay circuit-breaking system comprises an electric signal sensor, a time-delay control microprocessor and an on-off switch c, wherein the electric signal sensor and the on-off switch c are connected in the continuous discharge unit and are connected with the time-delay control microprocessor.

Furthermore, two needle-shaped electrodes are arranged on the same vertical axis, and a fuel sample to be tested is placed between the two electrodes; the high-voltage arm of the impulse voltage generator is connected with the electrode above, and the grounding end and the electrode below are simultaneously connected into a grounding grid of the test room; one end of a capacitor bank of the continuous discharge unit is connected with the electrode above through an inductor, and the other end and the electrode below are simultaneously connected into a grounding grid.

Furthermore, the on-off switch a, the on-off switch b and the on-off switch c are all direct current contactors.

Further, when the discharge simulation device works, the high-voltage arc starting unit breaks down the gap of the electrode instantly to ignite an electric arc, then the continuous discharge unit continuously supplies power to maintain the electric arc for a long time so as to simulate long continuous current discharge in lightning strike.

Has the advantages that:

the discharge simulation device can obtain long continuous current discharge with different current sizes by presetting different capacitor bank capacitor capacities and charging voltages, and establishes a corresponding relation between the discharge current size and the capacitor capacities as well as the charging voltage, so that the discharge current size can be independently controlled by controlling the capacitor capacities and the charging voltages of the capacitor banks; the duration of the discharge is controlled by presetting different delay times. The discharge simulation device can simulate discharge according to typical parameters (current size and duration) of actual lightning, is convenient and accurate in parameter control, and provides a test basis for the research of forest lightning stroke fire.

Drawings

FIG. 1 is a schematic diagram of the main components of a long continuous current discharge simulation apparatus with independently controllable current magnitude and duration according to the present invention;

FIG. 2 is a circuit diagram of a long continuous current discharge simulator with independently controllable current magnitude and duration according to the present invention;

FIG. 3 is a discharge waveform example diagram of a long continuous current discharge simulator with independently controllable current magnitude and duration according to the present invention.

Wherein, 1, a high-voltage arc striking unit; 2. a continuous discharge unit; 3. a capacitance capacity control system; 4. a charging voltage control system; 5. a delayed trip system; 6. a surge voltage generator; 7. a high pressure arm; 8. a ground terminal; 9. a capacitor bank; 10. a sub-capacitor group; 11. a direct current charging device; 12. an inductance; 13. an electrode; 14. a grounding grid; 15. a selector switch; 16. an on-off switch a; 17. a voltage sensor; 18. a voltage comparison microprocessor; 19. an on-off switch b; 20. an electrical signal sensor; 21. a delay control microprocessor; 22. an on-off switch c; 23. a voltage dividing resistor; 24. a voltage measuring probe b.

Detailed Description

An embodiment of the invention is described in detail below, the main components of which (fig. 1), a circuit diagram (fig. 2) and an example diagram of the waveforms (fig. 3) are shown in the drawings. It should be noted that the embodiments described below with reference to the drawings are illustrative and are only for explaining the present invention, and not for limiting the present invention.

In the description of the present invention, it should be noted that specific physical quantity values such as "peak value about 40 kv", "rated voltage 400 v", "capacitance capacity 0.2 farad", "diameter 4 mm", "electrode distance 10 mm" and the like are preferable parameters based on the embodiment, and are only for clearly describing the present invention, and do not indicate or imply that the physical quantity concerned is only the value, and thus, it is not to be understood as a limitation of the present invention.

In the description of the present invention, it should be noted that the terms "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate directions or positional relationships based on the orientations or positional relationships shown in the drawings of the present examples, and are only for the purpose of clearly describing the present invention, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be installed and operated in a specific orientation, and thus, are not to be construed as limiting the present invention.

In the description of the present invention, unless otherwise specified, it is to be noted that the terms "connected", "accessed", "connected", and the like are to be understood in a broad sense, for example, in some cases, direct connection or connection through an intermediate medium of a plurality of elements or devices, and for some electrical elements, connection to an input terminal or connection to an output terminal of an electrical element according to a physical function of a connected object. The specific meaning of the above terms can be understood by those of ordinary skill in the art as appropriate.

In the description of the present invention, unless otherwise specified, it should be noted that the appearance of devices with the same term expressing different positions or functions is distinguished by adding lowercase letters after the term, for example, in the discharge simulation apparatus, a plurality of places are used as "power-on switches", the positions where they are connected and the roles of them are different, and a plurality of places are used as "power-on switches a", "power-on switches b", "power-on switches c" … …, instead of indicating or implicitly referring to different devices, and thus, it is not to be understood as a limitation to the present invention.

The invention provides a long continuous current discharge simulation device with independently controllable current magnitude and duration. As shown in fig. 1 and 2, the discharge simulation apparatus mainly includes a high-voltage arcing unit 1, a continuous discharge unit 2, a capacitance control system 3, a charging voltage control system 4, a time-delay circuit-breaking system 5, and control software. The high-voltage arc starting unit 1 and the continuous discharge unit 2 are both connected with an electrode 13. And the capacitance capacity control system 3, the charging voltage control system 4 and the time delay circuit breaking system 5 are all connected with the continuous discharging unit 2.

The main body of the high-voltage arc starting unit 1 is an impulse voltage generator 6, which can generate a high-voltage pulse with a very short time, which is tens of microseconds, and a peak value of the high-voltage pulse is tens of kilovolts, preferably about 40 kilovolts. The continuous discharge unit 2 comprises a capacitor bank 9 and a dc charging device 11 for charging the capacitor bank 9. The capacitor bank 9 is formed by connecting 5 sub-capacitor banks 10 in parallel. Two needle-like electrodes 13 are arranged on the same vertical axis, and a fuel sample to be measured is placed between the two electrodes 13. The high-voltage arm 7 of the impulse voltage generator 6 is connected with the upper electrode 13, and the grounding end 8 and the lower electrode 13 are simultaneously connected with a grounding grid 14 of the test room. One end of the capacitor bank 9 of the continuous discharge unit 2 is connected with the upper electrode 13 through a large inductor 12, and the other end and the lower electrode 13 are simultaneously connected into a grounding grid 14. When the discharge simulation device works, the high-voltage arc starting unit 1 instantaneously breaks down the gap of the electrode 13 to ignite an electric arc, then the continuous discharge unit 2 continuously supplies power to maintain the electric arc for a long time, the electric arc current is 100-300 amperes, and the duration is 100-500 milliseconds, so that the long continuous current discharge in lightning strike is simulated. The rated voltage of the dc charging device 11 is 400 v. The capacitance of the sub-capacitor group 10 is 0.2 farad, and the rated voltage is 400 v. The electrodes 13 are graphite electrodes with a diameter of 4 mm and an electrode spacing of 10 mm. The inductance value of the inductor 12 is 1.7 millihenry.

The capacitance capacity control system 3 includes a selection switch 15 and a plurality of on-off switches a 16, and in this embodiment, the selection switch 15 and the on-off switches a 16 are preferably a 5-step knob switch and 5 dc contactors a, respectively. 5 gears of the 5-gear knob switch are respectively and correspondingly connected to 1, 2, 3, 4 and 5 direct current contactors a, and the 5 direct current contactors a are respectively connected to the parallel branches of the 5 sub-capacitor groups 10 of the continuous discharge unit 2. The number of the direct current contactors a in a closed state can be changed by turning the 5-gear knob switch to change the gear, so that the number of the sub capacitor groups 10 connected to the capacitor group 9 is changed, and the capacitance capacity of the capacitor group 9 is further changed. The capacitance capacities corresponding to 5 gears of the 5-gear knob switch are respectively 0.2, 0.4, 0.6, 0.8 and 1.0 method.

The charging voltage control system 4 comprises a voltage sensor 17, a voltage comparison microprocessor 18, an on-off switch b 19 and control software. In this embodiment, preferably, the voltage sensor 17 is a pair of voltage measuring probes a connected to two terminals of the capacitor bank 9, and signal output terminals of the voltage measuring probes a are connected to the voltage comparison microprocessor 18; the on-off switch b 19 is a direct current contactor b and is connected to the connection line of the direct current charging device 11 and the capacitor bank 9, and the control end of the direct current contactor b is connected with the voltage comparison microprocessor 18. In the charging process of the capacitor bank 9, the voltage sensor 17 is used for acquiring the voltage value of the capacitor bank 9 in real time and transmitting the voltage value to the voltage comparison microprocessor 18, the voltage comparison microprocessor 18 can be used for comparing the voltage of the capacitor bank 9 acquired by the voltage measurement probe a with a reference voltage preset by control software, and when the voltage of the capacitor bank reaches the preset reference voltage, the charging is stopped by disconnecting the direct current contactor b. At this time, the voltage across the capacitor bank 9 is a predetermined reference voltage, i.e., a charging voltage.

The delay open-circuit system 5 comprises an electric signal sensor 20, a delay control microprocessor 21, an on-off switch c22 and control software. In this embodiment, preferably, the electrical signal sensor 20 is a voltage dividing resistor 23 connected in series in the circuit of the continuous discharge unit 2 and a voltage measuring probe b 24 connected to two ends of the voltage dividing resistor, and the signal output end of the voltage measuring probe b 24 is connected to the delay control microprocessor 21; the on-off switch c22 is a high-current dc contactor and is connected in the circuit of the continuous discharge unit 2. When the discharge simulation device operates, delay time (namely discharge duration) is preset through control software, once long continuous current discharge starts, the electric signal sensor 20 detects an electric signal and triggers the delay control microprocessor 21 to start timing, and when the timed time reaches the delay time preset by the control software, the discharge circuit is cut off by disconnecting the high-current direct-current contactor, and discharge is stopped. At this time, the actual discharge duration is a preset delay time, i.e., a discharge duration. The on-off switch c22 has a current rating of 400 amps.

The discharge simulation device can obtain long continuous current discharge with different current sizes by presetting the capacitance capacity and the charging voltage of different capacitance groups 9, and establish the corresponding relation between the discharge current size and the capacitance capacity as well as the charging voltage, so that the discharge current size can be independently controlled by controlling the capacitance capacity and the charging voltage of the capacitance groups 9; the duration of the discharge is controlled by presetting different delay times. Referring to fig. 3, this embodiment provides an exemplary graph of waveforms having a capacitance of 1.0 normal (corresponding to the selection switch 15 at 5 th position), a charging voltage, and a discharging duration of 300 volts and 200 milliseconds, respectively.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (4)

1. A long continuous current discharge simulation device with independently controllable current magnitude and duration is characterized in that: the device comprises a high-voltage arc striking unit (1), a continuous discharging unit (2), a capacitance capacity control system (3), a charging voltage control system (4) and a time-delay circuit-breaking system (5); the high-voltage arc starting unit (1) and the continuous discharge unit (2) are both connected with the electrode (13); the capacitance capacity control system (3), the charging voltage control system (4) and the time-delay circuit-breaking system (5) are connected with the continuous discharging unit (2);

the high-voltage arc starting unit (1) comprises an impulse voltage generator (6);

the continuous discharging unit (2) comprises a capacitor bank (9) and a direct current charging device (11) for charging the capacitor bank (9);

the capacitor bank (9) is formed by connecting a plurality of sub-capacitor banks (10) in parallel;

the capacitance capacity control system (3) comprises a selection switch (15) and a plurality of on-off switches a (16), wherein the selection switch (15) is connected with the on-off switches a (16) to control the on-off of the on-off switches a (16); the number of the on-off switches a (16) is equal to that of the sub-capacitor groups (10) in the continuous discharge unit (2), and the on-off switches a (16) are connected to the parallel branch where the sub-capacitor groups (10) are located;

the charging voltage control system (4) comprises a voltage sensor (17), a voltage comparison microprocessor (18) and an on-off switch b (19); the voltage sensor (17) is connected to two ends of a capacitor bank (9) in the continuous discharging unit (2), and an on-off switch b (19) is connected between the capacitor bank (9) and the direct current charging device (11);

the voltage sensor (17) and the on-off switch b (19) are connected with a voltage comparison microprocessor (18);

the time-delay circuit-breaking system (5) comprises an electric signal sensor (20), a time-delay control microprocessor (21) and an on-off switch c (22), wherein the electric signal sensor (20) and the on-off switch c (22) are connected in the continuous discharge unit (2) and are connected with the time-delay control microprocessor (21).

2. The long continuous current discharge simulator with independently controllable current magnitude and duration according to claim 1, wherein: the two electrodes (13) are arranged on the same vertical axis, and a fuel sample to be tested is placed between the two electrodes (13); a high-voltage arm (7) of the impulse voltage generator (6) is connected with an electrode (13) above, and a grounding end (8) and the electrode (13) below are simultaneously connected into a grounding grid (14) of the test room; one end of a capacitor bank (9) of the continuous discharge unit (2) is connected with an upper electrode (13) through an inductor (12), and the other end and a lower electrode (13) are simultaneously connected into a grounding grid (14).

3. The long continuous current discharge simulator with independently controllable current magnitude and duration according to claim 1, wherein: the on-off switch a (16), the on-off switch b (19) and the on-off switch c (22) are all direct current contactors.

4. The long continuous current discharge simulator with independently controllable current magnitude and duration according to claim 2, wherein: when the discharge simulation device works, the high-voltage arc starting unit (1) breaks down the gap of the electrode (13) instantly to ignite an electric arc, then the continuous discharge unit (2) continuously supplies power to maintain the electric arc for a long time so as to simulate long continuous current discharge in lightning.

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