CN102298108B - Impact characteristic simulation test apparatus of earthing device and method thereof - Google Patents
Impact characteristic simulation test apparatus of earthing device and method thereof Download PDFInfo
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- CN102298108B CN102298108B CN 201110136985 CN201110136985A CN102298108B CN 102298108 B CN102298108 B CN 102298108B CN 201110136985 CN201110136985 CN 201110136985 CN 201110136985 A CN201110136985 A CN 201110136985A CN 102298108 B CN102298108 B CN 102298108B
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Abstract
The invention provides an impact characteristic simulation test apparatus of an earthing device and a method thereof, and belongs to the simulation test field of the earthing device. The impact characteristic simulation test apparatus comprises an impact current generator, a semispherical test bath, a simulation earthing device, a core penetration type current sensor, an impact voltage divider, a wideband digital oscilloscope, a coaxial shielding cable and the like. According to the method, by employing the apparatus in the invention, an impact simulation test of the earthing device is carried out. According to the invention, a soil discharge process that a real lightning current goes through the earthing device and flows to surrounding soil is simulated accurately, and an impact earthing impedance of the earthing device and an impact flow rule of the earthing device are measured. The apparatus has the characteristics of high reliability, good security, low test cost and the like. The apparatus and the method can be widely applied to measurement of the impact impedance and the impact flow rule of the earthing device under an effect of a heavy impact current, and are especially suitable for measurement of the impact impedance and the impact flow rule of the earthing device under an effect of a lightning current.
Description
Technical field
The invention belongs to the modelling technique field of earthing device, be specifically related to impact characteristics simulation test device and the simulation experiment method of earthing device.
Background technology
The impact characteristics of research earthing device has very great meaning to safety, the reliability service of electric system, the impact characteristics of measuring earthing device by the method for test is the important means of ground connection research always, utilize the simulation test of earthing device impact characteristics can measure accurately, reliably the impact characteristics of earthing device, thereby instruct the rational planning and construction of earthing device in electric system, for the safe operation of electric system provides safeguard.
The test unit of existing earthing device impact characteristics and method, as application number be 200910063596.9 " shock ground resistance of transmission line tower measuring method and instrument thereof ", this patent is disclosed is at first the earthing device of electric power line pole tower to be applied to dash current, then measure response voltage and the dash current amplitude of shaft tower earthing device, finally utilize instrument to carry out the data acquisition and processing (DAP) of voltage, electric current, thereby calculate the impulse earthed resistance that obtains earthing device in engineering reality." impact grounding impedance measuring system and measuring method thereof " patent that and for example application number is 201010166901.X, disclosed measuring system comprises: high-voltage DC power supply, high-voltage pulse electric capacity, discharge loop, high-voltage charging switch, high-voltage discharging switch, with the divertor of high-voltage pulse electric capacity and discharge loop series connection and the water resistance voltage divider that is connected with reference stake resistance in discharge loop.Disclosed method is: closed high charge switch at first, disconnect the motion sphere gap switch, and give the high-voltage pulse capacitor charging; When the voltage of high-voltage pulse electric capacity reaches predetermined value, disconnect the high-voltage charging switch, closing motion sphere gap switch, high-voltage pulse capacitor discharge; The surge voltage that utilization collects, dash current data are calculated the impulse grounding resistance value of earthing device.The major defect of above two patents is: 1. can only obtain the impulse grounding impedance of earthing device, can not obtain other impact characteristics of earthing device, as impacted the diffusing regularity of distribution etc.; 2. due to transportation and the restriction of other many conditions, in test, the amplitude of dash current is less, can not simulate preferably actual lightning current by the earthing device soil discharge process during soil diffusing towards periphery.Therefore can not obtain earthing device impact characteristics comprehensively and accurately.
Summary of the invention
The objective of the invention is for the test unit of existing earthing device impact characteristics and the deficiency of method, impact characteristics simulation test device and the method for earthing device are provided, there is versatility good, produce that the dash current amplitude is large, test findings is accurate, security good, can easily adjust the characteristics such as test parameters.
The technical scheme that realizes the object of the invention is: a kind of impact characteristics simulation test device of earthing device mainly comprises impulse current generator, semisphere test flume, analogue ground device, core-theaded type current sensor, impulse voltage divider, wide band digital oscillograph and coaxial shielded cable etc.
Described impulse current generator is commercial module, and instantaneous generation amplitude is 8
~200kA is adjustable, the wavefront time is 1.2
~20
variable, the wave rear time is 20
~1000
variable two index current waves.Impulse current generator mainly comprises: intelligent control system, pressure regulator, step-up transformer, silicon stack, wave regulating resistor R, harmonic inductance L, impulse capacitor group, pneumatic ignition pill gap, air compressor.Intelligent control system by optical fiber, is connected with pressure regulator, stomatal movement module respectively respectively.The air admission hole of described stomatal movement module is connected with air compressor by tracheae, the vent port of stomatal movement module is connected with inflator pump, in order to realize switching, the control in impulse capacitor group duration of charging of intelligent control system to the stomatal movement module of the output voltage of pressure regulator, air compressor; The end of incoming cables of pressure regulator is connected with the 220V power frequency supply by wire, and the leading-out terminal of pressure regulator is connected by wire with the former limit of step-up transformer; The secondary of step-up transformer is connected with wire with silicon stack; The wire of drawing of silicon stack is connected with wave regulating resistor R, harmonic inductance L successively; The wire of drawing of harmonic inductance is connected with the positive pole of impulse capacitor group; The impulse capacitor group is by 4
~20 10
~the impulse capacitor of 100 μ F composes in parallel, and wherein every 2
~3 impulse capacitors compose in parallel 1 group, each group arranges uniformly, and form one and take the annulus of not remaining silent that connected pneumatic ignition pill gap is the center of circle, each group pulse capacitor anode all is connected by first copper ball base of braiding copper strips and pneumatic ignition pill gap, when impulse capacitor discharges, circular ring type is arranged and can be made the electric current gone to the analogue ground device from each impulse capacitor arrive in a flash together, thereby improve the amplitude of dash current, the negative pole of impulse capacitor group is connected and ground connection by band steel with the outer wall of semisphere test flume; Pneumatic ignition pill gap is comprised of first copper ball, second copper ball and cylindrical aeration cylinder, the position of first copper ball is fixed and is connected with the positive pole of impulse capacitor group, second copper ball is connected by the electric current decanting point of the analogue ground device in the sand in weaving copper strips and being embedded in the semisphere test flume, in order to the dash current by impulse current generator output, be applied on the analogue ground device, the base of upper and lower half copper ball is right cylinder; The bottom surface of inflator pump is fixed on disc-shaped base, its roof opening, sidewall has an aperture and is connected with tracheae, the other end of tracheae is connected with the vent port of stomatal movement module, the internal diameter of cylindrical aeration cylinder and the base diameter of second copper ball equate, when the base of second copper ball is placed in inflator pump, inflator pump possesses impermeability preferably; The vent port of stomatal movement module is connected by tracheae with the cylindrical aeration cylinder, when intelligent control system is sent triggering command, the vent port of stomatal movement module is open, air-flow enters in described inflator pump, second copper ball that promotes pneumatic ignition pill gap moves upward, and clearance is discharged and punctures.After triggering command disappears, second copper ball falls back to original position under the effect of gravity, wait for next time and triggering, in addition, being connected with the copper strips of certain-length between the base of second copper ball and round base, is in order to prevent that second copper ball from being shifted onto high position by air-flow and first copper ball collides and damage ball gap.
Described semisphere test flume is diameter 0.5
~10m, outer wall by thick be 1
~the hemispherical shell that the material of 3mm is steel plate, be used as the collector of analogue ground, the infinite distance the earth that the simulation electromotive force is zero, the outer wall of the semisphere test flume rear ground connection that is connected with the negative pole of the impulse capacitor group of aforementioned impulse current generator by band steel.Being equiped with particle diameter in described semisphere test flume is 0.05
~the moisture sand of 1mm, come the artifical resistance rate to be by the water cut that changes sand
soil.Be embedded with the analogue ground device in moisture sand.
The material of described analogue ground device is identical with the material of tested actual earthing device, and the physical dimension of described analogue ground device (being length and sectional area) is 5 with the ratio n of the physical dimension (being length and sectional area) of tested actual earthing device
~100(n is the simulation ratio).On the conductor of described analogue ground device every 5
~20cm chooses a point (being the axial current tested point of the analogue ground device) row labels of going forward side by side, and the core-theaded type current sensor is sleeved on described axial current tested point place, in order to the axial current at the axial current tested point place of measure analog earthing device.Described analogue ground device is embedded in the sand in aforementioned semisphere test flume, the degree of depth of burying underground is determined according to the depth of burying and the simulation ratio n of actual earthing device, and the center that requires the analogue ground device equates to the distance of each point on aforementioned semisphere test flume outer wall, to guarantee the accuracy of simulation test.Electric current decanting point place at described analogue ground device is connected with the base of second copper ball of the pneumatic ignition pill gap of aforementioned impulse current generator by the braiding copper strips, in order to the analogue ground device, to inject dash current, the analogue ground device is carried out to the impact characteristics simulation test.
Described core-theaded type current sensor is by magnetic conduction skeleton, copper coil, integrating circuit, bayonet nut connector body and polymer insulation shell do not form.Described not magnetic conduction skeleton is that internal diameter is 2
~10cm, external diameter are 2.5
~12cm, diameter of section are 1
~the annulus that 4cm, material are non-magnetic polymkeric substance, its effect is fixing copper coil, avoids the sensor iron core saturated when measuring heavy impulse current simultaneously.Described copper coil is 0.44 by wire diameter
~1.67mm the copper enameled wire evenly be wound on the not magnetic conduction skeleton of annular, the number of turn of coiling is 50
~1000 circles, the extension line at copper coil two ends is connected with the input end of integrating circuit, in order to induction electromotive force
carry out integration, thereby obtain
the size that t changes in time.The output terminal of integrating circuit is connected with the bayonet nut connector plug of coaxial shielded cable one end by bayonet nut connector body, the other end of coaxial shielded cable is connected with oscillographic the second input channel CH2 of wide band digital by bayonet nut connector plug, in order to the output signal by the core-theaded type current sensor, by coaxial shielded cable, exports oscillographic the second input channel CH2 of wide band digital to.Being cast with thickness on described core-theaded type current sensor surface is 0.8
~the polymer insulation shell of 2cm, damage measuring equipment in order to prevent large electric current from scurrying into the measuring circuit at core-theaded type current sensor place.When the described polymer insulation shell of core-theaded type current sensor surface casting, bayonet nut connector body should be arranged on outside the polymer insulation shell, facilitate the signal output part of core-theaded type current sensor to be connected with coaxial shielded cable.The Measurement bandwidth of core-theaded type current sensor is 160Hz
~4 MHz, it not only has good response characteristic, can measure accurately heavy impulse current, and because the core-theaded type current sensor with circuit-under-test, directly contacting of electricity does not occur.When the waveform of measuring injection analogue ground device total current and amplitude thereof, described core-theaded type current sensor is sleeved on the braiding copper strips of analogue ground device Injection Current; When the axial current waveform of each tested point of measure analog earthing device and amplitude thereof, described core-theaded type current sensor is sleeved on the axial current tested point of analogue ground device.
The core-theaded type current sensor is identical with the principle of work of Rogowsky (Rogowski) coil, and the voltage that the magnetic field that utilizes tested electric current to produce is responded to is in coil measured electric current.According to electromagnetic induction principle, through in the conductor of core-theaded type current sensor coil, pass through electric current
the time, the induction electromotive force produced in the Rogowski coil
with
relation suc as formula shown in 1..
The M value is relevant with the geometric configuration of coil.
Described impulse voltage divider is commercial module, and measuring amplitude is-400
~400kV, frequency are 0
~the voltage signal of 1MHz, measured signal does not produce attenuation and distortion.Described impulse voltage divider is arranged on the output terminal of aforesaid impulse current generator, and the dash current decanting point of the high-pressure side of impulse voltage divider analogue ground device interior with aforesaid semisphere test flume by the braiding copper strips is connected; The band steel that the earth terminal of impulse voltage divider is connected with the negative pole of aforesaid impulse capacitor group with the outer wall of described semisphere test flume by the braiding copper strips connects; The signal output part of impulse voltage divider is equiped with bayonet nut connector plug coaxial shielded cable by two ends is connected with oscillographic the first input channel CH1 of wide band digital, in order to export the surge voltage measuring-signal to the wide band digital oscillograph.
Described wide band digital oscillograph is commercial product, and gather amplitude at 2 signal sampling channels is-400 simultaneously
~400V, frequency are 0
~the voltage signal of 100MHz, sample frequency is 0
~10GS/s, memory capacity are 0
~100MB, can guarantee precision and the length of collection signal.The oscillographic power supply of described wide band digital is self-contained storage battery and inverter integrated drive generator or off-line ups power, this not only can improve the signal to noise ratio (S/N ratio) of the signal that the wide band digital oscillograph obtains, and can prevent impulse current generator when electric discharge, heavy impulse current causes laboratory earth mat current potential sharply raise and damage the wide band digital oscillograph with entering.
Described coaxial shielded cable is commercial SYV-75-5 type radio-frequency cable, and installs respectively bayonet nut connector plug additional at the two ends of coaxial shielded cable, for convenient, connects.The effect of coaxial shielded cable is respectively the measuring-signal of impulse voltage divider and core-theaded type current sensor to be transferred to oscillographic the first input channel CH1 of wide band digital and the second input channel CH2, the screen layer of coaxial shielded cable can guarantee that the interference level that signal is subject in transmitting procedure is lower, thereby guarantees higher measuring accuracy.
A kind of impact characteristics simulation experiment method of earthing device, utilize apparatus of the present invention, and through determining simulation strip part, the joint test loop, carry out the impulsive discharge test, and the steps such as data computing are carried out the shock simulation test of earthing device, and its concrete steps are as follows:
(1) determine the simulation test condition
At first confirmed test condition, determine material, size, the depth of burying of electric current decanting point position, the analogue ground device of resistivity, the analogue ground device of sand in wave head time of dash current and wave rear time, amplitude, semisphere test flume, the position of core-theaded type current sensor etc., concrete determine as follows:
1. the wave head time of dash current and wave rear time is definite, and according to wave head time and the wave rear time of actual lightning current, and simulation ratio n determines.First respectively by the wave head time of actual lightning current, wave rear time divided by simulation ratio n, calculate wave head time, the wave rear time of the dash current of simulation test, then reach wave head time, the wave rear time of calculated dash current by the size that changes wave regulating resistor R in the impulse current generator loop, harmonic inductance L.
2. determining of the amplitude of dash current, determine according to amplitude and the simulation ratio n of actual lightning current.First by the amplitude of actual lightning current divided by n
2, calculate the dash current amplitude of simulation test, then carry out the amplitude of dash current in adjusting test by the charging voltage preset value of regulating impulse capacitor group in impulse current generator.
3. the determining of the resistivity of sand in described semisphere test flume, bury the soil resistivity at place underground and determine according to actual earthing device.By the airing sand or add the resistivity that water is regulated sand in sand, until the resistivity of sand is identical or close with the soil resistivity at the actual earthing device place of burying underground, (make the resistivity of sand and the difference of actual soil resistivity be controlled at 1%
~2%) till.
4. determining of the electric current decanting point position of described analogue ground device, determine according to the pad of actual earthing device and down conductor.The dash current decanting point position of analogue ground device is regulated in the tie point position that weaves copper strips and analogue ground device by adjusting.
5. the material of described analogue ground device is identical with the material of actual earthing device.The size of described analogue ground device and the depth of burying are determined according to size, the depth of burying and the simulation ratio n of actual earthing device, determine that the size of analogue ground device and the method for the depth of burying are: (1), according to the actual conditions of earthing device in engineering, determines physical dimension and the depth of burying thereof of actual earthing device; (2) by the physical dimension of actual earthing device and the depth of burying thereof respectively divided by simulation ratio n, obtain physical dimension and the depth of burying thereof of analogue ground device, its physical dimension comprises the length of conductor and the sectional area of conductor.
6. the position of described core-theaded type current sensor is definite: when the waveform of measuring injection analogue ground device total current and amplitude thereof, described core-theaded type current sensor is sleeved on the braiding copper strips of analogue ground device Injection Current; When the axial current waveform of each tested point of measure analog earthing device and amplitude thereof, first each axial current tested point on the analogue ground device is numbered (from the electric current decanting point, by 1,2,3 order number consecutively), more described core-theaded type current sensor is set in successively on each axial current tested point of analogue ground device.
(2) joint test loop
After (1) step completes, according to apparatus of the present invention, wiring is carried out in test loop.That is: connecting line with band steel is connected the negative pole of described impulse capacitor group respectively and ground connection with the outer wall of semisphere test flume; Connecting line with the braiding copper strips is connected the base of second copper ball of described impulse current generator with the electric current decanting point of analogue ground device; With coaxial shielded cable, oscillographic the first input channel CH1 of the signal output part of impulse voltage divider and wide band digital is connected, in order to the High Voltage Impulse Waveform by the analogue ground device, exports the wide band digital oscilloscope display to; The core-theaded type current sensor is sleeved on on the braiding copper strips that is used to the analogue ground device to inject dash current or the axial current tested point place of analogue ground device, in order to total Injection Current of measure analog earthing device or the axial current of each axial current tested point, oscillographic the second input channel CH2 of the signal output part of core-theaded type current sensor and wide band digital is connected, in order to the waveform of the axial current of total Injection Current of analogue ground device that the core-theaded type current sensor measurement is obtained or tested point, exports the wide band digital oscilloscope display to.Finally check that whether wiring correct, connect whether good, when whole wiring connect good after, just can carry out next step.
(3) carry out the impulsive discharge test
After (2) step completes, first open air compressor, restart the intelligent control system of impulse current generator, charging voltage is set in intelligent control system, make charging voltage value equal charging voltage preset value definite in (1) step, and according to the size of charging voltage, be set the duration of charging, when charging voltage is greater than 50kV, duration of charging is set to 90s, otherwise the duration of charging is set to 60s, this is too fast and make the accelerated deterioration of impulse capacitor group or the phenomenon such as inhomogeneous of charging occurs for fear of charging.After setting completes, press " starting charging " key, when the charging of impulse capacitor group reaches the predeterminated voltage value, press " triggering " key, second copper ball of the pneumatic ignition pill gap of impulse current generator ball gap in the process moved upward is breakdown, dash current
act on the analogue ground device in the semisphere test flume, thereby complete the one-shot discharge test, successively the analogue ground device is carried out to the impulsive discharge test, in order to the axial current of the tested point of the total Injection Current of measure analog earthing device or analogue ground device, and to require the time interval of every twice impulsive discharge test be 2
~4 minutes, guarantee that the electrical specification of sand in the later half spherical test flume of each impulsive discharge has time enough to recover normal, the sand characteristic while making each impulsive discharge test in the semisphere test flume is consistent, thereby guarantees the accuracy of measurement result.
(4) data computing
After (3) step completes, when calculating the impulse grounding impedance of analogue ground device, act on impulse current waveform on the analogue ground device and the High Voltage Impulse Waveform on the analogue ground device according to what show on (3) step wide band digital oscillograph, read dash current
amplitude
and surge voltage
amplitude
, and utilize expression formula 3. to calculate the impulse grounding impedance of analogue ground device.
For guaranteeing the reliability of measurement data, repeat 5 times and measure under the prerequisite that does not change dash current and core-theaded type current sensor position.Therefore after measuring the one-shot impedance ground, return to (3) step, again trigger the impulse current generator electric discharge and read dash current according to dash current and the High Voltage Impulse Waveform of wide band digital oscillograph recording
amplitude
and surge voltage
amplitude
, the impulse grounding impedance of 3. calculating the analogue ground device according to expression formula.5 times so repeatedly, obtain 5 impulse grounding impedances of same analogue ground device, give up 5 maximal value and minimum value in value, all the other 3 impulse grounding impedances are averaging, this mean value i.e. the impulse grounding impedance of dash current effect Imitating earthing device for this reason.Measure the impulse grounding impedance of other amplitude dash current effect Imitating earthing device as continued, at first return to the charging voltage of (1) step joint impulse capacitor group, then enter (2) step joint test circuit, finally loop (3) step and (4) step, according to the wide band digital oscilloscope measurement to electric current and the impulse grounding impedance of the voltage data dash current effect Imitating earthing device that calculates this amplitude.
When calculating the impact diffusing rule of analogue ground device, the axial current amplitude of each axial current tested point obtained according to (3) pacing, the diffusing size of each section conductive surface of calculating analogue ground device.At first the core-theaded type current sensor is sleeved on and is numbered in test
axial current tested point place, then complete successively (2) step, (3) step, according to what show on the wide band digital oscillograph
the axial current waveform at some place, read its amplitude
for guaranteeing data reliability, repeating 5 times under the prerequisite that does not change impulse current waveform, amplitude and core-theaded type current sensor position measures, measure interval at least 3 minutes every 2 times, the electrical specification of guaranteeing sand in the later half spherical test flume of each impulsive discharge has the sufficiently long time to recover normal, finally give up 5 maximal value and minimum value in measured value, 3 remaining measured values are averaging, this mean value is as the current amplitude at axial current tested point m place.After measuring the current amplitude at axial current tested point m place, under the prerequisite that does not change impulse current waveform, amplitude, change the position of core-theaded type current sensor, by its be sleeved on the axial current tested point (
) locate, repeat above-mentioned test procedure, obtain point (
) the axial current amplitude.By the position of continuous change core-theaded type current sensor, measure the axial current amplitude of all the other each axial current tested points, until obtain the axial current amplitude of all axial current tested points on the analogue ground device.
After measuring the axial current amplitude of all tested points on the analogue ground device, utilize two adjacent tested points
,
the axial current amplitude at place is respectively
,
carry out calculation level
and the point
between the amplitude of surperficial diffusing of conductor segment be:
After calculating the surperficial diffusing value of all conductor segment of analogue ground device, obtained the impact diffusing rule of analogue ground device under this dash current effect.
After the present invention adopts technique scheme, mainly there is following effect:
(1) capacity of the impulse current generator of apparatus of the present invention is very large, therefore can in simulation test, produce the dash current that amplitude is very high, thereby can accurately simulate actual lightning current by the earthing device soil discharge process of complexity during the soil diffusing towards periphery, the reliability of analog reslt is improved.
(2) total Injection Current that the core-theaded type current sensor of apparatus of the present invention not only can the measure analog earthing device, thereby calculate the impulse grounding impedance of analogue ground device, and axial current that can also each axial current tested point of measure analog earthing device, thereby calculate the conductive surface diffusing rule of dash current effect Imitating earthing device.
(3) total Injection Current that the core-theaded type current sensor of apparatus of the present invention can the Measurement accuracy earthing device and the axial current of each axial current tested point of earthing device, therefore do not affect again circuit-under-test, guaranteed the precision of the dash current that measures in the simulation test.
(4) apparatus of the present invention diameter is 0.5
~moisture sand in the semisphere test flume of 10m can be simulated the soil at place, actual earthing device place, to originally need to become indoor carrying out in the outdoor test of carrying out, not only saved experimentation cost, and made test greatly reduced by the degree of weather and environmental impact.
(5) the wide band digital oscillograph of apparatus of the present invention adopts self-contained storage battery and inverter combination or the power supply of off-line ups power, can effectively prevent impulse current generator when electric discharge, laboratory earth mat current potential from sharply raising and damage the generation of the measuring equipment phenomenons such as wide band digital oscillograph, core-theaded type current sensor.
(6) the inventive method has simply, easy and simple to handle, can easily adjust the advantages such as test parameters.In addition, the simulation test security is good, and accuracy and the reliability of analog reslt are high.
The present invention can be widely used in measuring the impulse grounding impedance of earthing device under the heavy impulse current effect and impacting the diffusing rule, is specially adapted to measure the impact impedance of the earthing device under the lightning current effect and impacts the diffusing rule.
The accompanying drawing explanation
The principle schematic that Fig. 1 is apparatus of the present invention;
The structural representation of the impulse capacitor group that Fig. 2 is Fig. 1;
The structural representation that the pneumatic ignition pill gap that Fig. 3 is Fig. 1 is amplified;
The structural representation of the core-theaded type current sensor that Fig. 4 is Fig. 1;
The A-A cut-open view that Fig. 5 is Fig. 4.
In figure: 1 impulse current generator, 2 intelligent control systems, 3 pressure regulators, 4 step-up transformers, 5 silicon stacks, 6 wave regulating resistors, 7 harmonic inductance, 8 impulse capacitor groups, 9 pneumatic ignition pill gaps, 10 air compressor, 11 impulse voltage dividers, 12 wide band digital oscillographs, 13 semisphere test flumes, 14 analogue ground devices, 15 core-theaded type current sensors, 16 coaxial shielded cables, 17 optical fiber, 18 impulse capacitors, 19 first copper balls, 20 second copper balls, 21 bases, 22 inflator pumps, 23 braiding copper strips, 24 pedestals, 25 magnetic conduction skeletons not, 26 polymer insulation shells, 27 copper coils, 28 bayonet nut connector bodies, 29 integrating circuit.
Embodiment
Further illustrate the present invention below in conjunction with embodiment.
embodiment 1
As Fig. 1
~shown in 5, a kind of impact characteristics simulation test device of earthing device, mainly comprise impulse current generator 1, semisphere test flume 13, analogue ground device 14, core-theaded type current sensor 15, impulse voltage divider 11, wide band digital oscillograph 12 and coaxial shielded cable 16 etc.
Described impulse current generator 1 is commercial module, and instantaneous generation amplitude is 8
~200kA is adjustable, the wavefront time is 1.2
~20
variable, the wave rear time is 20
~1000
variable two index current waves.Impulse current generator 1 mainly comprises: intelligent control system 2, pressure regulator 3, step-up transformer 4, silicon stack 5, wave regulating resistor 6, harmonic inductance 7, impulse capacitor group 8, pneumatic ignition pill gap 9, air compressor 10.Intelligent control system 2 by optical fiber 17, is connected with pressure regulator 3, stomatal movement module respectively respectively.The air admission hole of described stomatal movement module is connected with air compressor 10 by tracheae, the vent port of stomatal movement module is connected with inflator pump 22, in order to switching, the control in 8 duration of charging of impulse capacitor group of the stomatal movement module of the output voltage of realizing 2 pairs of pressure regulators 3 of intelligent control system, air compressor 10, the end of incoming cables of pressure regulator 3 is electrically connected to the power frequency city of 220V/50Hz by wire, and the leading-out terminal of pressure regulator 3 is connected by wire with the former limit of step-up transformer 4, the secondary of step-up transformer 4 is connected with silicon stack 5 use wires, the wire of drawing of silicon stack 5 is connected with wave regulating resistor 6, harmonic inductance 7 successively, the wire of drawing of harmonic inductance 7 is connected with the positive pole of impulse capacitor group 8, impulse capacitor group 8 is composed in parallel by the impulse capacitor of 4 10 μ F, wherein every 2 impulse capacitors compose in parallel 1 group, each group arranges uniformly, and form one and take the annulus of not remaining silent that connected pneumatic ignition pill gap 9 is the center of circle, each group pulse capacitor anode all base of first copper ball 19 by braiding copper strips and pneumatic ignition pill gap 9 is connected, when impulse capacitor discharges, circular ring type is arranged and can be made the electric current gone to analogue ground device 14 from each impulse capacitor arrive in a flash together, thereby improve the amplitude of dash current, the negative pole of impulse capacitor group group 8 is connected and ground connection by band steel with the outer wall of semisphere test flume 13, pneumatic ignition pill gap 9 is comprised of first copper ball 19, second copper ball 20 and cylindrical aeration cylinder 22, the position of first copper ball 19 is fixed and is connected with the positive pole of impulse capacitor group 8, second copper ball 20 is connected by the electric current decanting point of the analogue ground device 14 in the sand in weaving copper strips and being embedded in semisphere test flume 13, in order to the dash current by impulse current generator 1 output, be applied on analogue ground device 14, the base of upper and lower half copper ball is right cylinder, the bottom surface of inflator pump 22 is fixed on disc-shaped base 24, its roof opening, sidewall has an aperture and is connected with tracheae, the other end of tracheae is connected with the vent port of stomatal movement module, the internal diameter of cylindrical aeration cylinder 22 and the base of second copper ball 21 equal diameters, when the base 21 of second copper ball 20 is placed in inflator pump 22, inflator pump 22 possesses impermeability preferably, the vent port of stomatal movement module is connected by tracheae with cylindrical aeration cylinder 22, when intelligent control system 2 is sent triggering command, the vent port of stomatal movement module is open, air-flow enters in described inflator pump 22, second copper ball 20 that promotes pneumatic ignition pill gap 9 moves upward, and clearance is discharged and punctures.After triggering command disappears, second copper ball 20 falls back to original position under the effect of gravity, wait for next time and triggering, in addition, 24 copper strips that are connected with certain-length of the base 21 of second copper ball 20 and round base are in order to prevent that second copper ball 20 from being shifted onto high position by air-flow and first copper ball 19 collides and damage ball gap.
That described semisphere test flume 13 is diameter 0.5m, outer wall by thick be the material of the 1mm hemispherical shell that is steel plate, be used as the collector of analogue ground, the infinite distance the earth that the simulation electromotive force is zero, the outer wall of the semisphere test flume 13 rear ground connection that is connected with the negative pole of the impulse capacitor group 8 of aforementioned impulse current generator 1 by band steel.Being equiped with particle diameter in described semisphere test flume 13 is 0.05
~the moisture sand of 1mm, come the artifical resistance rate to be by the water cut that changes sand
soil.Be embedded with analogue ground device 14 in moisture sand.
The material of described analogue ground device 14 is identical with the material of tested actual earthing device, the ratio n of the physical dimension of described analogue ground device 14 (being length and sectional area) and the physical dimension (being length and sectional area) of tested actual earthing device be taken as in the present invention for 100(n be the simulation ratio).On the conductor of described analogue ground device 14 every 5
~20cm chooses a point (being the axial current tested point of the analogue ground device 14) row labels of going forward side by side, core-theaded type current sensor 15 is sleeved on described axial current tested point place, in order to the axial current at the axial current tested point place of measure analog earthing device 14.Described analogue ground device 14 is embedded in the sand in aforementioned semisphere test flume 13, the degree of depth of burying underground is determined according to the depth of burying and the simulation ratio n of actual earthing device, and the center that requires analogue ground device 14 equates to the distance of each point on aforementioned semisphere test flume 13 outer walls, to guarantee the accuracy of simulation test.Electric current decanting point place at described analogue ground device 14 is connected with the base 21 of second copper ball 20 of the pneumatic ignition pill gap 9 of aforementioned impulse current generator 1 by the braiding copper strips, in order to analogue ground device 14, to inject dash current, analogue ground device 14 is carried out to the simulation test of impact characteristics.
Described core-theaded type current sensor 15 is by magnetic conduction skeleton 25, copper coil 27, integrating circuit 29, bayonet nut connector body 28 and polymer insulation shell 26 do not form.Described not magnetic conduction skeleton 25 is that 2cm, external diameter are that 2.5cm, diameter of section are the annulus that 1cm, material are non-magnetic polymkeric substance for internal diameter, and its effect is fixing copper coil 27, avoids the sensor iron core saturated when measuring heavy impulse current simultaneously.The copper enameled wire that described copper coil 27 is 0.44mm by wire diameter evenly is wound on the not magnetic conduction skeleton 25 of annular, and the number of turn of coiling is 50 circles, and the extension line at copper coil 27 two ends is connected with the input end of integrating circuit 29, in order to induction electromotive force
carry out integration, thereby obtain
the size that t changes in time.The output terminal of integrating circuit 29 is connected with the bayonet nut connector plug of coaxial shielded cable 16 1 ends by bayonet nut connector body 28, the other end of coaxial shielded cable 16 is connected with the second input channel CH2 of wide band digital oscillograph 12 by bayonet nut connector plug, exports the second input channel CH2 of wide band digital oscillograph 12 to by coaxial shielded cable 16 in order to the output signal by core-theaded type current sensor 15.Be cast with on described core-theaded type current sensor 15 surfaces the polymer insulation shell 26 that thickness is 0.8cm, in order to prevent large electric current from scurrying into the measuring circuit at core-theaded type current sensor 15 places, damage measuring equipment.When the described polymer insulation shell 26 of core-theaded type current sensor 15 surface casting, should make bayonet nut connector body 28 be exposed to outside polymer insulation shell 26, facilitate the signal output part of core-theaded type current sensor 15 to be connected with coaxial shielded cable 16.The Measurement bandwidth of core-theaded type current sensor is 160Hz
~4 MHz, it not only has good response characteristic, can measure accurately heavy impulse current, and because core-theaded type current sensor 15 with circuit-under-test, directly contacting of electricity does not occur.When the waveform of measuring injection analogue ground device 14 total currents and amplitude thereof, described core-theaded type current sensor 15 is sleeved on the braiding copper strips of analogue ground device 14 Injection Currents; When the axial current waveform of measure analog earthing device 14 each tested points and amplitude thereof, described core-theaded type current sensor 15 is sleeved on the axial current tested point of analogue ground device 14.
Described impulse voltage divider 11 is commercial module, and measuring amplitude is-400
~400kV, frequency are 0
~the voltage signal of 1MHz, measured signal does not produce attenuation and distortion.Described impulse voltage divider 11 is arranged on the output terminal of aforesaid impulse current generator 1, and the dash current decanting point of the high-pressure side of impulse voltage divider 11 analogue ground device 14 interior with aforesaid semisphere test flume 13 by the braiding copper strips is connected; The band steel that the earth terminal of impulse voltage divider 11 is connected with the negative pole of aforesaid impulse capacitor group 8 with the outer wall of described semisphere test flume 13 by the braiding copper strips connects; The signal output part of impulse voltage divider 11 is equiped with bayonet nut connector plug coaxial shielded cable 16 by two ends is connected with the first input channel CH1 of wide band digital oscillograph 12, in order to export the surge voltage measuring-signal to wide band digital oscillograph 12.
Described wide band digital oscillograph 12 is commercial Tektronix 1012 type digital oscilloscopes, and gather amplitude at 2 signal sampling channels is-400 simultaneously
~400V, frequency are 0
~the voltage signal of 100MHz, sample frequency is 0
~10GS/s, memory capacity are 0
~100MB, can guarantee precision and the length of collection signal.The power supply of described wide band digital oscillograph 12 is self-contained storage battery and inverter integrated drive generator, this not only can improve the signal to noise ratio (S/N ratio) of the signal that wide band digital oscillograph 12 obtains, and can prevent impulse current generator 1 electric discharge the time, heavy impulse current causes laboratory earth mat current potential sharply raise and damage wide band digital oscillograph 12 with entering.
Described coaxial shielded cable 16 is commercial SYV-75-5 type radio-frequency cable, and installs respectively bayonet nut connector plug additional at the two ends of coaxial shielded cable 16, for convenient, connects.The effect of coaxial shielded cable 16 is the first input channel CH1 and the second input channel CH2 that respectively measuring-signal of impulse voltage divider 11 and core-theaded type current sensor 15 transferred to wide band digital oscillograph 12, the screen layer of coaxial shielded cable 16 can guarantee that the interference level that signal is subject in transmitting procedure is lower, thereby guarantees higher measuring accuracy.
embodiment 2
A kind of impact characteristics simulation test device of earthing device, with embodiment 1, wherein: impulse capacitor group 8 is composed in parallel by the impulse capacitor of 12 30 μ F, and wherein every 3 impulse capacitors compose in parallel 1 group.That semisphere test flume 13 is diameter 5m, outer wall by thick be the material of the 2mm hemispherical shell that is steel plate.Magnetic conduction skeleton 25 is not that 5cm, external diameter are that 6cm, diameter of section are 2cm for internal diameter.The copper enameled wire that copper coil 27 is 1.12mm by wire diameter evenly is wound on the not magnetic conduction skeleton 25 of annular, and the number of turn of coiling is 700 circles.Core-theaded type current sensor 15 surfaces are cast with the polymer insulation shell 26 that thickness is 1cm.
embodiment 3
A kind of impact characteristics simulation test device of earthing device, with embodiment 1, wherein: impulse capacitor group 8 is composed in parallel by the impulse capacitor of 20 100 μ F, and wherein every 2 impulse capacitors compose in parallel 1 group.That semisphere test flume 13 is diameter 10m, outer wall by thick be the material of the 3mm hemispherical shell that is steel plate.Magnetic conduction skeleton 25 is not that 10cm, external diameter are that 12cm, diameter of section are 2cm for internal diameter.The copper enameled wire that copper coil 27 is 1.67mm by wire diameter evenly is wound on the not magnetic conduction skeleton 25 of annular, and the number of turn of coiling is 1000 circles.Core-theaded type current sensor 15 surfaces are cast with the polymer insulation shell 26 that thickness is 2cm.The power supply of described wide band digital oscillograph 12 is off-line UPS.
embodiment 4
A kind of concrete steps of impact characteristics simulation experiment method of earthing device are as follows:
(1) determine simulation strip part
At first confirmed test condition, determine material, size, the depth of burying of electric current decanting point position, the analogue ground device 14 of resistivity, the analogue ground device 14 of sand in wave head time of dash current and wave rear time, amplitude, semisphere test flume 13, the position of core-theaded type current sensor 15 etc., concrete determine as follows:
1. the wave head time of dash current and wave rear time is definite, and according to wave head time and the wave rear time of actual lightning current, and simulation ratio n determines.First respectively by the wave head time of actual lightning current, wave rear time divided by simulation ratio n, calculate wave head time, the wave rear time of the dash current of simulation test, then reach wave head time, the wave rear time of calculated dash current by the size that changes wave regulating resistor 6 in impulse current generator 1 loop, harmonic inductance 7.
2. determining of the amplitude of dash current, determine according to amplitude and the simulation ratio n of actual lightning current.First by the amplitude of actual lightning current divided by n
2, calculate the dash current amplitude of simulation test, then carry out the amplitude of dash current in adjusting test by the charging voltage preset value of regulating impulse capacitor group 8 in impulse current generator 1.
3. the determining of the resistivity of sand in described semisphere test flume 13, bury the soil resistivity at place underground and determine according to actual earthing device.By the airing sand or add the resistivity that water is regulated sand in sand, until the resistivity of sand is identical or close with the soil resistivity at the actual earthing device place of burying underground, (make the resistivity of sand and the difference of actual soil resistivity be controlled at 1%
~2%) till.
4. determining of the electric current decanting point position of described analogue ground device 14, determine according to the pad of actual earthing device and down conductor.The dash current decanting point position of analogue ground device 14 is regulated in the tie point position that weaves copper strips and analogue ground device 14 by adjusting.
5. the material of described analogue ground device 14 is identical with the material of actual earthing device.The size of described analogue ground device 14 and the depth of burying are determined according to size, the depth of burying and the simulation ratio n of actual earthing device, determine that the size of analogue ground device 14 and the method for the depth of burying are: (1), according to the actual conditions of earthing device in engineering, determines physical dimension and the depth of burying thereof of actual earthing device; (2) by the physical dimension of actual earthing device and the depth of burying thereof respectively divided by simulation ratio n, obtain physical dimension and the depth of burying thereof of analogue ground device 14, its physical dimension comprises the length of conductor and the sectional area of conductor.
6. the position of described core-theaded type current sensor 15 is definite: when the waveform of measuring injection analogue ground device 14 total currents and amplitude thereof, described core-theaded type current sensor 15 is sleeved on the braiding copper strips of analogue ground device 14 Injection Currents; When the axial current waveform of measure analog earthing device 14 each tested points and amplitude thereof, first each axial current tested point on analogue ground device 14 is numbered (from the electric current decanting point, by 1,2,3 order number consecutively), more described core-theaded type current sensor 15 is set in successively on each axial current tested point of analogue ground device 14.
(2) joint test loop
After (1) step completes, according to apparatus of the present invention, wiring is carried out in test loop.That is: connecting line with band steel is connected the negative pole of described impulse capacitor group 8 respectively and ground connection with the outer wall of semisphere test flume 13, connecting line with the braiding copper strips is connected the base 21 of second copper ball 20 of described impulse current generator 1 with the electric current decanting point of analogue ground device 14, with coaxial shielded cable 16, the signal output part of impulse voltage divider 11 is connected with the first input channel CH1 of wide band digital oscillograph 12, exports wide band digital oscillograph 12 in order to the High Voltage Impulse Waveform by analogue ground device 14 and show, core-theaded type current sensor 15 is sleeved on on the braiding copper strips that is used to analogue ground device 14 to inject dash current or the axial current tested point place of analogue ground device 14, in order to total Injection Current of measure analog earthing device 14 or the axial current of each axial current tested point, the signal output part of core-theaded type current sensor 15 is connected with the second input channel CH2 of wide band digital oscillograph 12, exporting wide band digital oscillograph 12 in order to the waveform of the axial current of total Injection Current of core-theaded type current sensor 15 being measured to the analogue ground device 14 obtained or tested point shows.Finally check that whether wiring correct, connect whether good, when whole wiring connect good after, just can carry out next step.
(3) carry out the impulsive discharge test
After (2) step completes, first open air compressor 10, restart the intelligent control system 2 of impulse current generator 1, in intelligent control system 2, charging voltage is set, make charging voltage value equal charging voltage preset value definite in (1) step, and according to the size of charging voltage, be set the duration of charging, when charging voltage is greater than 50kV, duration of charging is set to 90s, otherwise the duration of charging is set to 60s, this is too fast and make 8 accelerated deteriorations of impulse capacitor group or the phenomenon such as inhomogeneous of charging occurs for fear of charging.After setting completes, press " starting charging " key, when 8 chargings of impulse capacitor group reach the predeterminated voltage value, press " triggering " key, second copper ball 20 ball gap in the process moved upward of the pneumatic ignition pill gap 9 of impulse current generator 1 is breakdown, dash current
act on the analogue ground device 14 in semisphere test flume 13, thereby complete the one-shot discharge test, successively analogue ground device 14 is carried out to the impulsive discharge test, in order to the axial current of the tested point of the total Injection Current of measure analog earthing device 14 or analogue ground device 14, and to require the time interval of every twice impulsive discharge test be 2
~4 minutes, guarantee that the electrical specification of sand in the later half spherical test flume 13 of each impulsive discharge has time enough to recover normal, the sand characteristic while making each impulsive discharge test in semisphere test flume 13 is consistent, thereby guarantees the accuracy of measurement result.
(4) data computing
After (3) step completes, when calculating the impulse grounding impedance of analogue ground device 14, act on impulse current waveform on analogue ground device 14 and the High Voltage Impulse Waveform on analogue ground device 14 according to what show on (3) step wide band digital oscillograph 12, read dash current
amplitude
and surge voltage
amplitude
, and utilize expression formula 3. to calculate the impulse grounding impedance of analogue ground device 14.
For guaranteeing the reliability of measurement data, repeat 5 times and measure under the prerequisite that does not change dash current and core-theaded type current sensor 15 positions.Therefore after measuring the one-shot impedance ground, return to (3) step, again trigger impulse current generator 1 electric discharge and read dash current according to dash current and the High Voltage Impulse Waveform of wide band digital oscillograph 12 records
amplitude
and surge voltage
amplitude
, the impulse grounding impedance of 3. calculating analogue ground device 14 according to expression formula.5 times so repeatedly, obtain 5 impulse grounding impedances of same analogue ground device 14, give up 5 maximal value and minimum value in value, all the other 3 impulse grounding impedances are averaging, this mean value i.e. the impulse grounding impedance of dash current effect Imitating earthing device 14 for this reason.Measure the impulse grounding impedance of other amplitude dash current effect Imitating earthing device 14 as continued, at first return to the charging voltage of (1) step joint impulse capacitor group 8, then enter (2) step joint test circuit, finally loop (3) step and (4) step, the electric current measured according to wide band digital oscillograph 12 and voltage data calculate the impulse grounding impedance of the dash current effect Imitating earthing device 14 of this amplitude.
When calculating the impact diffusing rule of analogue ground device 14, the axial current amplitude of each axial current tested point obtained according to (3) pacing, the diffusing size of calculating analogue ground device 14 each section conductive surfaces.At first core-theaded type current sensor 15 is sleeved on and is numbered in test
axial current tested point place, then complete successively (2) step, (3) step, according to what show on wide band digital oscillograph 12
the axial current waveform at some place, read its amplitude
for guaranteeing data reliability, repeating 5 times under the prerequisite that does not change impulse current waveform, amplitude and core-theaded type current sensor 15 positions measures, measure interval at least 3 minutes every 2 times, the electrical specification of guaranteeing sand in the later half spherical test flume 13 of each impulsive discharge has the sufficiently long time to recover normal, finally give up 5 maximal value and minimum value in measured value, 3 remaining measured values are averaging, this mean value is as the current amplitude at axial current tested point m place.After measuring the current amplitude at axial current tested point m place, under the prerequisite that does not change impulse current waveform, amplitude, change the position of core-theaded type current sensor 15, by its be sleeved on the axial current tested point (
) locate, repeat above-mentioned test procedure, obtain point (
) the axial current amplitude.By the position of continuous change core-theaded type current sensor 15, measure the axial current amplitude of all the other each axial current tested points, until obtain the axial current amplitude of all axial current tested points on analogue ground device 14.
After measuring the axial current amplitude of all tested points on analogue ground device 14, utilize two adjacent tested points
,
the axial current amplitude at place is respectively
,
carry out calculation level
and the point
between the amplitude of surperficial diffusing of conductor segment be:
After calculating the surperficial diffusing value of analogue ground device 14 all conductor segment, obtained the impact diffusing rule of analogue ground device 14 under this dash current effect.
Claims (3)
1. the impact characteristics simulation test device of an earthing device, mainly comprise impulse current generator (1), semisphere test flume (13), analogue ground device (14), core-theaded type current sensor (15), impulse voltage divider (11), wide band digital oscillograph (12), coaxial shielded cable (16) is characterized in that:
Described semisphere test flume (13) is diameter 0.5
~10m, outer wall by thick be 1
~the hemispherical shell that the material of 3mm is steel plate forms, the outer wall of semisphere test flume (13) the rear ground connection that is connected with the negative pole of the impulse capacitor group (8) of aforementioned impulse current generator (1) by band steel, being equiped with particle diameter in described semisphere test flume (13) is 0.05
~the moisture sand of 1mm, carrying out the artifical resistance rate by the water cut that changes sand is 10
~the soil of 1500 Ω m is embedded with analogue ground device (14) in moisture sand, the material of described analogue ground device (14) is identical with the material of tested actual earthing device, the physical dimension of described tested actual earthing device, be the physical dimension of length and sectional area and analogue ground device (14), the ratio n of length and sectional area is 5
~100, n is the simulation ratio, on the conductor of described analogue ground device (14) every 5
~it is the axial current tested point of analogue ground device (14) row labels of going forward side by side that 20cm chooses a point, core-theaded type current sensor (15) is sleeved on described axial current tested point place, described analogue ground device (14) is embedded in the sand in aforementioned semisphere test flume (13), the degree of depth of burying underground is determined according to the depth of burying and the simulation ratio n of actual earthing device, and the center that requires analogue ground device (14) equates to the distance of each point on aforementioned semisphere test flume (13) outer wall, electric current decanting point place at described analogue ground device (14) is connected with the base (21) of second copper ball (20) of the pneumatic ignition pill gap (9) of aforementioned impulse current generator (1) by the braiding copper strips,
Described core-theaded type current sensor (15) is comprised of not magnetic conduction skeleton (25), copper coil (27), integrating circuit (29), bayonet nut connector body (28) and polymer insulation shell (26), and described not magnetic conduction skeleton (25) is 2 for internal diameter
~10cm, external diameter are 2.5
~12cm, diameter of section are 1
~the annulus that 4cm, material are non-magnetic polymkeric substance, described copper coil (27) is 0.44 by wire diameter
~1.67mm the copper enameled wire evenly to be wound on the not magnetic conduction skeleton (25) of annular upper, the number of turn of coiling is 50
~1000 circles, the extension line at copper coil (27) two ends is connected with the input end of integrating circuit (29), the output terminal of integrating circuit (29) is connected with the bayonet nut connector plug of coaxial shielded cable (16) one ends by bayonet nut connector body (28), the other end of coaxial shielded cable (16) is connected with the second input channel CH2 of wide band digital oscillograph (12) by bayonet nut connector plug, and being cast with thickness on described core-theaded type current sensor (15) surface is 0.8
~the polymer insulation shell (26) of 2cm, when core-theaded type current sensor (15) the surface described polymer insulation shell of casting (26), bayonet nut connector body (28) should be arranged on outside polymer insulation shell (26), when the waveform of measuring injection analogue ground device (14) total current and amplitude thereof, described core-theaded type current sensor (15) is sleeved on the braiding copper strips of analogue ground device (14) Injection Current; When the axial current waveform of each tested point of measure analog earthing device (14) and amplitude thereof, described core-theaded type current sensor (15) is sleeved on the axial current tested point of analogue ground device (14);
Described impulse voltage divider (11) is commercial module, and measuring amplitude is-400
~400kV, frequency are 0
~the voltage signal of 1MHz, measured signal does not produce attenuation and distortion, described impulse voltage divider (11) is arranged on the output terminal of aforesaid impulse current generator (1), and the dash current decanting point of the high-pressure side of impulse voltage divider (11) analogue ground device (14) interior with aforesaid semisphere test flume (13) by the braiding copper strips is connected; The band steel that the earth terminal of impulse voltage divider (11) is connected with the negative pole of aforesaid impulse capacitor group (8) with the outer wall of described semisphere test flume (13) by the braiding copper strips connects; The signal output part of impulse voltage divider (11) is equiped with bayonet nut connector plug coaxial shielded cable (16) by two ends is connected with the first input channel CH1 of wide band digital oscillograph (12).
2. according to the impact characteristics simulation test device of earthing device claimed in claim 1, it is characterized in that: the instantaneous generation amplitude of described impulse current generator (1) is that 8 ~ 200kA is adjustable, the wavefront time is that 1.2 ~ 20 μ s are variable, the wave rear time is two index current waves that 20 ~ 1000 μ s are variable; The Measurement bandwidth of described core-theaded type current sensor (15) is 160Hz ~ 4 MHz, has good response characteristic; The measurement amplitude of described impulse voltage divider (11) is the voltage signal that-400 ~ 400kV, frequency are 0 ~ 1MHz, and measured signal does not produce attenuation and distortion; 2 signal sampling channels of described wide band digital oscillograph (12) gather the voltage signal that amplitude is 0 ~ 100MHz for-400 ~ 400V, frequency simultaneously, and sample frequency is 0 ~ 10GS/s, and memory capacity is 0 ~ 100MB.
3. the impact characteristics simulation experiment method of an earthing device, utilize the impact characteristics simulation test device of earthing device claimed in claim 1, and the concrete steps of shock simulation test that it is characterized in that carrying out earthing device are as follows:
(1) determine the simulation test condition
At first confirmed test condition, determine material, size, the depth of burying of electric current decanting point position, the analogue ground device (14) of resistivity, the analogue ground device (14) of sand in wave head time of dash current and wave rear time, amplitude, semisphere test flume (13), the position of core-theaded type current sensor (15), concrete determine as follows:
1. the wave head time of dash current and wave rear time determines, according to wave head time and the wave rear time of actual lightning current, and simulation ratio n determines, first respectively by the wave head time of actual lightning current, wave rear time divided by simulation ratio n, calculate wave head time, the wave rear time of the dash current of simulation test, then reach wave head time, the wave rear time of calculated dash current by the size that changes wave regulating resistor (6) in impulse current generator (1) loop, harmonic inductance (7);
2. determining of the amplitude of dash current, determine according to amplitude and the simulation ratio n of actual lightning current, first by the amplitude of actual lightning current divided by n
2, calculate the dash current amplitude of simulation test, then carry out the amplitude of dash current in adjusting test by the charging voltage preset value of regulating impulse capacitor group (8) in impulse current generator (1);
3. the resistivity of the middle sand of described semisphere test flume (13) determines, bury the soil resistivity at place underground determines according to actual earthing device, by the airing sand or add the resistivity that water is regulated sand in sand, until the soil resistivity that the resistivity of sand is buried place underground with actual earthing device is identical or close, even the difference of the resistivity of sand and actual soil resistivity is controlled at 1%
~till 2%;
4. the electric current decanting point position of described analogue ground device (14) determines, according to the pad of actual earthing device and down conductor, determine, the dash current decanting point position of analogue ground device (14) is regulated in the tie point position that weaves copper strips and analogue ground device (14) by adjusting;
5. the material of described analogue ground device (14) is identical with the material of actual earthing device, the size of described analogue ground device (14) and the depth of burying are determined according to size, the depth of burying and the simulation ratio n of actual earthing device, determine that the size of analogue ground device (14) and the method for the depth of burying are: (1), according to the actual conditions of earthing device in engineering, determines physical dimension and the depth of burying thereof of actual earthing device; (2) by the physical dimension of actual earthing device and the depth of burying thereof respectively divided by simulation ratio n, obtain physical dimension and the depth of burying thereof of analogue ground device (14), its physical dimension comprises the length of conductor and the sectional area of conductor;
6. the position of described core-theaded type current sensor (15) is definite: when the waveform of measuring injection analogue ground device (14) total current and amplitude thereof, described core-theaded type current sensor (15) is sleeved on the braiding copper strips of analogue ground device (14) Injection Current; When the axial current waveform of each tested point of measure analog earthing device (14) and amplitude thereof, first each axial current tested point on analogue ground device (14) is numbered, from the electric current decanting point, order number consecutively by 1,2,3, more described core-theaded type current sensor (15) is set in successively on each axial current tested point of analogue ground device (14);
(2) joint test loop
After (1) step completes, according to device claimed in claim 1, wiring is carried out in test loop, that is: connect line with band steel and respectively the negative pole of described impulse capacitor group (8) is connected with the outer wall of semisphere test flume (13) and ground connection; Connecting line with the braiding copper strips is connected the base of second copper ball (20) of described impulse current generator (1) with the electric current decanting point of analogue ground device (14); With coaxial shielded cable (16), the signal output part of impulse voltage divider (11) is connected with the first input channel CH1 of wide band digital oscillograph (12); Core-theaded type current sensor (15) is sleeved on on the braiding copper strips that is used to analogue ground device (14) to inject dash current or the axial current tested point place of analogue ground device (14), the signal output part of core-theaded type current sensor (15) is connected with the second input channel CH2 of wide band digital oscillograph (12), finally check that whether wiring is correct, whether well connect, after whole wiring connect well, just can carry out next step;
(3) carry out the impulsive discharge test
After (2) step completes, first open air compressor (10), restart the intelligent control system (2) of impulse current generator (1), in intelligent control system (2), charging voltage is set, make charging voltage value equal charging voltage preset value definite in (1) step, and according to the size of charging voltage, be set the duration of charging, when charging voltage is greater than 50kV, duration of charging is set to 90s, otherwise the duration of charging is set to 60s, after setting completes, press " starting charging " key, when impulse capacitor group (8) charging reaches the predeterminated voltage value, press " triggering " key, second copper ball (20) ball gap in the process moved upward of the pneumatic ignition pill gap of impulse current generator (1) (9) is breakdown, dash current i
cact on the analogue ground device (14) in semisphere test flume (13), thereby complete the one-shot discharge test, successively analogue ground device (14) is carried out to the impulsive discharge test, and the axial current of the tested point of the total Injection Current of measure analog earthing device (14) or analogue ground device (14), requiring the time interval of every twice impulsive discharge test is 2
~4 minutes,
(4) data computing
After (3) step completes, when calculating the impulse grounding impedance of analogue ground device (14), according to (3) step wide band digital oscillograph (12) upper show act on impulse current waveform on analogue ground device (14) and the High Voltage Impulse Waveform on analogue ground device (14), read dash current i
camplitude I
pwith surge voltage u
camplitude U
p, and utilize expression formula 3. to calculate the impulse grounding impedance of analogue ground device (14);
Z
i=U
p/I
p ③
Repeating 5 times under the prerequisite that does not change dash current and core-theaded type current sensor (15) position measures, therefore after measuring the one-shot impedance ground, return to (3) step, again trigger impulse current generator (1) electric discharge and read dash current i according to dash current and the High Voltage Impulse Waveform of wide band digital oscillograph (12) record
camplitude I
pwith surge voltage u
camplitude U
p, 3. calculate the impulse grounding impedance of analogue ground device (14) according to expression formula, 5 times so repeatedly, obtain 5 impulse grounding impedances of same analogue ground device (14), give up 5 maximal value and minimum value in value, all the other 3 impulse grounding impedances are averaging, this mean value i.e. the impulse grounding impedance of dash current effect Imitating earthing device (14) for this reason, measure the impulse grounding impedance of other amplitude dash current effect Imitating earthing device (14) as continued, at first return to the charging voltage of (1) step joint impulse capacitor group (8), then enter (2) step joint test circuit, finally loop (3) step and (4) step, the impulse grounding impedance of the dash current effect Imitating earthing device (14) that the electric current measured according to wide band digital oscillograph (12) and voltage data calculate this amplitude,
When calculating the impact diffusing rule of analogue ground device (14), the axial current amplitude of each axial current tested point obtained according to (3) pacing, calculate the diffusing size of each section conductive surface of analogue ground device (14), at first core-theaded type current sensor (15) is sleeved on to the axial current tested point place that is numbered m in test, then complete successively (2) step, (3) step, axial current waveform according to the upper m point place shown of wide band digital oscillograph (12), read its amplitude I
m, do not changing impulse current waveform, repeating 5 times under the prerequisite of amplitude and core-theaded type current sensor (15) position measures, measure interval at least 3 minutes every 2 times, finally give up 5 maximal value and minimum value in measured value, 3 remaining measured values are averaging, this mean value is as the current amplitude at axial current tested point m place, after measuring the current amplitude at axial current tested point m place, do not changing impulse current waveform, under the prerequisite of amplitude, change the position of core-theaded type current sensor (15), it is sleeved on to axial current tested point (m+1) locates, repeat above-mentioned test procedure, obtain the axial current amplitude of point (m+1), position by continuous change core-theaded type current sensor (15), measure the axial current amplitude of all the other each axial current tested points, until obtain the axial current amplitude of the upper all axial current tested points of analogue ground device (14),
After the axial current amplitude that measures the upper all tested points of analogue ground device (14), utilize the axial current amplitude at two adjacent tested point m, m+1 place to be respectively I
m, I
m+1come the amplitude of the surperficial diffusing of conductor segment between calculation level m and some m+1 to be:
④
After the surperficial diffusing value that calculates all conductor segment of analogue ground device (14), obtained the impact diffusing rule of analogue ground device (14) under this dash current effect.
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