RU2110885C1 - Lighting current simulator - Google Patents

Abstract

FIELD: pulse engineering; simulation of heavy-power of lighting currents surge in various power systems; investigation of physical mechanisms of high-amplitude currents. SUBSTANCE: connected in parallel with equipment under test are N modules, their number depending on number of produced surges; modules have storage capacitors and controlled switches whose synchronous operation is ensured by series-connected control panel, multichannel delay unit, and trigger unit; to avoid asynchronous operation of modules, opaque partitions are installed between lighting arrestors; multichannel design of switches reduces erosion of electrodes. Two modules are built around Arkad'ev-Marx circuit one of which has explosive wire instead of loading resistor. EFFECT: improved simulation of actual conditions due to producing discharge current in equipment under test in the form of series of separate surges. 5 dwg, 1 tbl

Description

 The invention relates to a pulsed technique and is intended to reproduce powerful pulsed lightning currents and switching noise in various power systems in order to study their effects on electronic equipment during testing of equipment.

 A device for simulating lightning currents [1], containing a capacitive drive connected in series, one lining of which is connected to an earthing switch, and a switch and an object under investigation are connected to the other, and a serial circuit consisting of a choke, a forming line and a spark gap is connected between the switch and the object under study. moreover, the forming line is made in the form of a bundle of wires having a variable radius.

 The disadvantage of this device is the impossibility of generating current pulses with an amplitude of the order of hundreds of kiloamperes due to the very large active and reactive resistance of the device connecting the capacitive storage device and the object under study.

 Closest to the claimed technical solution is the installation for simulating a lightning channel [4]. It contains two identical pulse generators, each of which consists of two sections connected in series, charged by voltage of opposite polarities, adjustable inductors, damping resistors with a short-circuit device, bypass special devices [2], four auxiliary capacitor banks, valves, additional inductance, discharge gap and test object.

 The installation allows you to simulate a lightning current pulse, consisting of two pulses, i.e. to reproduce the current pulse of the initial shock with a maximum amplitude of up to 200 kA and the pulse of the current of the repeated shock with a maximum amplitude of up to 100 kA [3].

 The disadvantage of this device is the inability to obtain pulses of discharge current in the form of a series of individual pulses. In addition, this device is characterized by a relatively high (up to 200 kV) voltage, which complicates its operation during testing.

 The invention is aimed at approximating the test conditions to the real one by generating discharge current pulses in the form of a series of individual pulses at a lower operating voltage.

 This is achieved by the fact that the number of modules connected in parallel with the test object is selected according to the number of simulating pulse series. Two modules are made according to the Arkadyev-Marx multiplication scheme, and the rest are simply capacitive drives with an output voltage equal to the charging one. The construction of the first module is based on the principle: the output voltage should be 3-4 times more than the charging voltage due to the multiplication circuit and exploding wires. To exclude unsynchronous operation between the arresters of the modules, lightproof partitions are installed. To increase the amplitude of the current and reduce erosion of the surfaces of the electrodes, the switches are multi-channel. Stable operation of the device is provided by the synchronization system for starting up switches, made in the form of a series-connected control panel, a multi-channel delay unit, each output circuit of which is connected to a corresponding start-up unit.

 In FIG. 1 shows a simplified electrical diagram of a simulator device; in FIG. 2 is an electrical diagram of its delay unit; in FIG. 3 is an equivalent circuit diagram of a first module with an exploding wire; in FIG. 4 - waveform of the current pulse generated by the prototype device; in FIG. 5 - waveform pulse generated by the proposed device.

 In FIG. 1, control panel 1, delay unit 2, trigger unit 3.1; 3.2; ... 3.N, multichannel managed switches 4.1; 4.2; ... 4.N; exploding wire 5; load resistance 6.1; 6.2; ... 6.N; modules 7.1; 7.2; ... 7.N with storage capacitors 8; charging elements 9.1; 9.2; ... 9.N; test object 10; coaxial measuring shunt 11; oscilloscope 12; measuring chamber 13; power source 14; lightproof dielectric partitions 15.1, 15.2 ... 15.N; integrated timers 16.1; 16.2; ... 16. N (figure 2); resistors 17; 18.1; 18.2; ... 18.N; 19.1; 19.2; ... 19.N; 20.1; 20.2 ... 20.N; 25.1; 25.2; ... 25.N; capacitors 21.1; 21.2; ... 21.N; 22.1; 22.1; ... 22.N; 23.2; 23.2; ... 23.N; 24.1 ... 24.N; diodes 26.1; 26.N; timing chain 19.1; 22.1; differentiating circuit 24.1; 25.1; 26.1.

 The device consists of N parallel connected 7.1 modules; 7.2; ... 7. N, each of which contains storage capacitors 8. The modules are connected to the test object 10 through load resistors 6.1; 6.2; ... 6.N. Storage capacitors are charged from the power source 14. The synchronous operation of the modules is carried out using the control panel 1, delay unit 2 and start blocks 3.1; 3.2; ... 3.N. The amplitude of the output current is measured by a coaxial shunt 11 and an oscilloscope 12 located in the measuring chamber 13. The storage capacitors 8 are charged from the power source 14.

 To form discharge current pulses in the form of a series of individual pulses (see Fig. 5), the device incorporates the principle of alternating discharge of 7.1 modules; 7.2; ... 7.N to the test object 10. If you use the prototype device [4], then a pulse will be generated (see Fig. 4), consisting only of pulses of the initial shock current (component A) and the intermediate shock current (component D ) To form a current pulse with a maximum amplitude of 200 kA, an inductive storage device is used in the device, two modules are made according to the Arkadyev-Marx scheme, and an explosive wire is installed between the output of the first module and the test object.

где
U_о, кВ - напряжение на выходе емкостного накопителя;
R_н, Ом - сопротивление нагрузки;
L_к , мкг - индуктивность разрядного контура.To transfer maximum energy from a capacitive storage to inductance, it is necessary to explode the conductor at maximum current. The conductor cross section in this case is determined by the relation

Where
U _about , kV - voltage at the output of the capacitive storage;
R _n Ohms - load resistance;
L _to , μg is the inductance of the discharge circuit.

The inductance of the discharge circuit is determined from the expression
L _to = L _g + L _p + L _OSH
Where
L _g - inductance of capacitive storage;
L _p - the inductance of the exploding conductor;
L _OSH - inductance of the busbar and the test object;
The conductors are selected so that the heating by switching current leads to their explosion at a time when almost all the energy of the capacitor is transferred to the inductance. The explosion is accompanied by a sharp increase in resistance and a short high-voltage pulse.

, при разряде на нее генератора Аркадьева-Маркса возникает импульс тока

,
где
C - емкость в ударе емкостного накопителя.Until the wire exploded, energy was stored in the module

, when a Arkadyev-Marx generator is discharged onto it, a current pulse

,
Where
C is the capacitance in shock capacitive storage.

где
e - основание натурального логарифма;
b - постоянный коэффициент для взрывающейся проволочки;
I - ток, проходящий через объект,
и характерным масштабом длительности

Роль нагрузки в первом модуле играет сама взрывающаяся проволочка.If L _k behaves like a line with lumped parameters, then when a wire explodes on a load Z _n > R _p , where R _{p is the} resistance of the wire, a pulse with an amplitude

Where
e is the base of the natural logarithm;
b is a constant coefficient for an exploding wire;
I is the current passing through the object,
and characteristic duration scale

The role of the load in the first module is played by the exploding wire itself.

раз больше по сравнению с той, которая была бы без взрывающейся проволочки. Амплитуда импульса в несколько раз превосходит ударное напряжение конденсаторного источника. Длительность импульса примерно в 20 раз меньше полупериода контура L_кC и может плавно регулироваться изменением длины и количества параллельно взрывающихся проводников (при сохранении их суммарного сечения).If the inductance of the test object is used as the load, then for L _n <L _k , a current pulse with a slope of

times more than that which would be without exploding wire. The amplitude of the pulse is several times higher than the shock voltage of the capacitor source. The pulse duration is approximately 20 times less than the half-cycle of the circuit L _to C and can be smoothly controlled by changing the length and number of concurrently exploding conductors (while maintaining their total cross section).

 To form a second pulse, a load resistance is established between the second module and the test object, the value of which is approximately 1.5 times greater than the active resistance of the blasting wire of the first module, and the capacitance in the shock of the second module is less than the first. This made it possible to obtain a pulse with an amplitude of 2.5 times less at the same output voltage, i.e. 80 kA. In this case, the impulse of the second shock current is delayed by the delay unit for the time necessary for the amplitude of the first impulse to fall to zero.

 Subsequent modules are made in a single-stage scheme. The capacity in the shock of each of the modules decreases, in the load resistance increases and is determined by the ratio RC = 30, where R is the module load resistance; C is the capacitance of the storage capacitor.

 The module switches are controlled by a synchronization system, which is made up of a series-connected control panel, a multi-channel delay unit, each output circuit of which is connected to the input of the corresponding start-up unit. To exclude unauthorized operation of the module switches, they are isolated from each other by lightproof dielectric partitions. To reduce erosion of electrodes and reduce inductance, multichannel switches are used in the device. The current parameters were recorded using a coaxial shunt and a storage oscilloscope.

 The device operates as follows.

 After charging the storage capacitors of modules 7.1, 7.2, ... 7.N from the power source 14 through the charging resistors 9.1, 9.2, ... 9.N, a trigger pulse is supplied from the control panel 1 to the input of the first timer 16.1, which begins to generate an output pulse . The capacitor 22.1 is charged until the voltage on its plates is lower than at the first threshold input. At the moment when the voltage on the capacitor is equal to the voltage at the threshold input, the timer 16.1 is activated and the capacitor 22.1 is quickly discharged.

 The trigger pulse is fed to the input of the trigger block 3.1, where its amplitude increases to the values necessary for the triggering of the switches 4.1, 4.2. With the arrival of the first trigger pulse to switch 4.1, the discharge of module 7.1 to the load formed by the exploding conductor 5 and test object 10 occurs. After the explosion of conductor 5, all the energy stored by module 7.1 passes through the formed channel to test object 10 in the form of a current pulse. After a set period of time, a triggering pulse is issued through a differentiating circuit 2 4.1, 2 5.1, 2 6.1 to the triggering block 3.2 and switches 4.2 of module 7.2. A second current pulse is generated on the test object 10 through the load resistances 6.1. Similarly, the rest of the timers of the delay unit and the start blocks are triggered and a current pulse is formed on the test object, consisting of a series of individual pulses following each other.

 A device was created at the applicant organization to simulate a series of lightning current pulses.

Structurally, the installation is framed as follows. Capacitive drives (modules) are assembled on capacitors IS5-200-U2 and IK50-6. The first module is assembled according to a two-stage Arkadyev-Marx scheme from two sections of 12 capacitors in each section (3 pieces in sequence and 4 pieces in parallel). The charging voltage was 15 kV, and the output voltage was 30 kV. The impact capacity of the first module is 20 μF. An exploding conductor is a copper wire 100 mm long and 0.12 mm in diameter. The inductance of the discharge circuit was 4.7 μH, the active resistance of the exploding wire and load R _p + R _n = 0.25 Ohm. The current pulse was 200 kA at a half-maximum duration of 55 μs. The impact capacity of the second module is 90 microfarads (two sections of 9 pieces of IS5-200 each), the output voltage is 30 kV and the load resistance is 0.33 Ohms. A current pulse of 80 kA with a duration at half maximum of 30 μs. The third, fourth and fifth modules are made according to a single-stage scheme with a shock capacitance of 60, 40, 20 μF and a load resistance of 0.5, 0.75 and 1.5 Ω, respectively. Current pulses of 30, 20 and 10 kA, respectively (see table).

где
k - коэффициент пропорциональности,
т.е. при L_к=4,7 мкГн, R_н=0,25 Ом, к=0,2...0,3 t_ф=5 мкс.When testing the installation parameters, it was revealed that with an increase in the number of exploding conductors with a constant cross section, an increase in the amplitude of the current pulse and a decrease in its front are observed. It was also established that the duration of the front is determined by the relation

Where
k is the coefficient of proportionality,
those. at L _k = 4.7 μH, R _n = 0.25 Ohm, k = 0.2 ... 0.3 t _f = 5 μs.

 The current surge in the first module was 2.7 times.

 The waveform of a current pulse from a series of five pulses is shown in FIG. 5. Pulse measurements were carried out with a coaxial shunt. Low resistance load resistances were made by winding a nichrome wire with a diameter of 0.2 mm. The results were recorded on a memory socillograph S8-13. The device has taken a number of measures to reduce electromagnetic interference. Cables are held in screens. The oscilloscope has autonomous power.

 The main characteristics of the device are given in the table. With constant parameters of the elements, the pulses have sufficient stability. The spread in the characteristics of current pulses from pulse to pulse does not exceed 20%.

 Thus, the proposed design of the device provides approximation of the test conditions to the real one by forming current pulses in the form of a series of individual pulses at lower voltages. It is possible to place this device in a mobile version, for example, in a truck body, and thereby test large-sized and stationary objects.

Claims (1)

 A device for simulating lightning currents containing a power source, charging and load resistors, starting blocks, a control panel and a set of N modules, each of which consists of storage capacitors and controlled switches, the module inputs being connected through charging resistors to the power source, and their outputs - parallel to the test object through the corresponding load resistor, characterized in that it additionally introduced an N-channel delay unit, the input of which is connected to the control panel, the first and last blowing outlets are connected to the input of the respective start of each block module, a load resistor of the first module is in the form of an exploding wire, and the product value load resistor (R) and discharge capacity (C) of each module satisfies the relation RC ≥ 30E

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