CN102914708A - Response characteristic testing device for metal oxide samples under steep wave front pulses - Google Patents

Abstract

The invention proposes a test device for the response characteristics of a metal oxide sample under a steep front pulse, including a steep front current pulse generator for generating a steep front current waveform; a test instrument for measuring the current and voltage of the test product Waveform: Connect the sample to the circuit formed by the steep-wave leading-edge current pulse generating device, and charge the two capacitors in the steep-wave leading-edge current pulse generating device through a DC power supply to break down the three-electrode switch to test the metal oxide sample Response characteristics under steep leading edge pulses. Because the test device adopts the integrated structure of capacitor and switch, the loop inductance is reduced, and because the copper tape is used to tightly wrap the capacitor, the loop inductance is reduced to the minimum, ensuring sufficient current amplitude and steep rising edge. With the increase of the current at the front of the steep wave, the residual pressure of the valve plate under the steep wave increases significantly.

Description

Device for testing the response characteristics of metal oxide samples under steep front pulses

technical field

The invention belongs to the field of power system overvoltage, in particular to a device for testing the response characteristics of metal oxide samples under steep front pulses.

Background technique

Experimental research shows that the gas-insulated metal-enclosed switchgear (GIS) isolation switch operation will generate high amplitude and steep very fast transient overvoltage (VFTO), which will affect the secondary equipment of GIS and its connected equipment insulation and shell connection. operation has a significant impact. At present, the method of GIS isolating switch with damping resistor proposed by Toshiba is widely used to suppress VFTO, and it has been well applied in practice. Both Changzhi Station and Nanyang Station of my country's UHV AC test demonstration project have adopted this scheme. Tsinghua University tried to install a high-frequency magnetic ring on the GIS high-voltage guide rod to suppress VFTO. A large number of laboratory studies have been carried out, and the effectiveness of this measure still needs to be verified through field application. In recent years, with the improvement of the performance of metal oxide arresters (hereinafter referred to as arresters), their suppression of VFTO has gradually become a research focus.

The arrester installed in the power system is mainly used to limit lightning and operating overvoltage. Because the VFTO wave head time is short, up to several ns, the oscillation frequency may reach more than 100MHz, and the response performance of the arrester valve plate at high frequency is limited, so it is rarely considered Limit VFTO with surge arresters. Since the 1980s, in order to develop arresters with excellent performance, the response characteristics of arresters under steep shock waves have been explored at home and abroad. BBC Company established a double exponential wave and a square wave current source to carry out experimental research on metal oxide resistors (hereinafter referred to as resistors) with different structures. The wave head time range of the output current waveform is 0.7~8μs. China Electric Power Research Institute has developed a steep impulse current wave device, which produces current waveforms of 0.1/0.2μs, 0.4/0.8μs, 0.8/3μs, 4/10μs, 8/20μs, 30/60μs, and the maximum current amplitude is 1kA , the influence of the structure and physical properties of the resistive sheet on the response characteristics of the arrester was studied experimentally. It can be seen that the above-mentioned experimental research is limited by the steep wave test power supply, and there are problems such as long current wave head time or small current amplitude, and the volt-ampere characteristics of the resistor sheet under VFTO steep wave have not been obtained. Since the volt-ampere characteristics of the resistor sheet under steep waves are the prerequisite for establishing the high-frequency model of the arrester, it is urgent to obtain the volt-ampere characteristics of the resistor sheet under the steep wave with the wave head time less than 100ns, and then simulate and study the suppression effect and application of the arrester on VFTO scope.

In the existing test technology, the pulse voltage is generally generated by the Marx generator and applied to the metal oxide sample, but this kind of experimental circuit is complicated, the stray parameters are large, and it is difficult to generate a steep current rising edge.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned steep wave test power supply for measuring the volt-ampere characteristics of metal oxide samples under steep front pulses, the purpose of the present invention is to propose a test device for the response characteristics of metal oxide samples under steep front pulses.

A device for testing the response characteristics of metal oxide samples under steep front pulses, the device comprising:

a steep-front current pulse generating device, connected to the sample, for generating a steep-front current waveform; and

The test instrument is connected with the test object and used to measure the current and voltage waveforms of the test object;

The steep front current pulse generating device includes a first capacitor, a three-electrode switch and a second capacitor connected in series in sequence, and the first capacitor and the second capacitor are provided with three terminals, and the first capacitor and the second capacitor are connected in series. The second terminal of the capacitor is respectively connected to the positive and negative poles of the power supply through a 1MΩ resistor, the first capacitor and the third terminal of the second capacitor are connected integrally through a three-electrode switch, and the first capacitor and the second capacitor are connected in an integrated manner. The first terminals of the two capacitors are respectively connected to the crimping parts installed at both ends of the test object through copper strips to form a discharge circuit.

Wherein, a screw rod is installed on the first terminal of the second capacitor, and a copper strip for connecting the test object and a grounding copper strip for grounding the discharge circuit are installed at the idle end of the screw rod.

Wherein, the test instrument includes a Rogowski coil set on the screw, a high-voltage probe connected to the crimping parts at both ends of the test object, a shielded cable, and an oscilloscope; The wave front current waveform is transmitted to the oscilloscope through the shielded cable; under the steep front current waveform, the high-voltage probe measures the current and voltage waveforms of the test product, and is transmitted to the oscilloscope through the shielded cable.

Wherein, the specific structure of the integrated connection is:

The three-electrode switch includes a dry gas tank, a trigger electrode packaged in the dry gas tank, and positive and negative high-voltage electrodes located on both sides of the trigger electrode. One side of the positive and negative high-voltage electrodes is respectively provided with a connecting screw. The third terminals of the first capacitor and the second capacitor are respectively provided with screw holes matching the connecting screw rods, and the connecting screw rods are screwed into the screw holes to realize the integrated connection of the first capacitor, the second capacitor and the three-electrode switch ; The dry gas tank is filled with an insulating gas medium.

Wherein, the insulating gas medium is air, SF ₆ gas or other inert gases.

Wherein, the crimping member adopts a flat cylinder structure made of conductive material.

Wherein, the first terminal is the low-voltage terminal of the first capacitor and the second capacitor; the second terminal and the third terminal are equipotential, and both are high-voltage terminals of the first capacitor and the second capacitor.

Wherein, the first terminal and the third terminal of the first capacitor are respectively located on opposite sides of the housing of the first capacitor, and the second terminal of the first capacitor is connected to the positive pole of the power supply, which is arranged on the same side as the third terminal. On the first capacitor shell on the adjacent side of the terminal; the first terminal and the third high-voltage terminal of the second capacitor are located on the opposite sides of the shell of the second capacitor, and the second terminal of the second capacitor Turn on the negative pole of the power supply, which is arranged on the second capacitor shell on the side adjacent to the third terminal.

Wherein, the copper strip connecting the first terminal of the first capacitor and one end of the test object, the copper strip connecting the first terminal of the second capacitor and the other end of the test object, the surfaces of the first capacitor and the second capacitor are respectively padded An insulating rubber is provided, and the above two copper strips are respectively wound on the surfaces of the first capacitor and the second capacitor.

The present invention adopts above-mentioned technical scheme, has the advantage that has:

Adopting the integrated coaxial structure design of capacitor and switch, the steep wave front current pulse generator has almost no inductance, which ensures that the generated current wave head time is short and meets the requirements of VFTO waveform;

The switch gap of the steep wave leading edge current pulse generating device can use a variety of gas insulating media, the gas pressure can be adjusted, and the out-of-band trigger breakdown mode makes the switch gap K have a higher breakdown voltage, and the generated current peak value is larger and the range is wider. Wide, can meet the measurement requirements of resistors with different performances.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the structural representation of steep wave front current pulse generating device in the testing device of the present invention;

Fig. 2 is the schematic circuit diagram of testing device of the present invention;

Fig. 3 is the voltage and current waveform diagram of resistor sheet QA22 under the 10kA steep wave front current in embodiment 1;

Fig. 4 is the comparison diagram of the valve plate volt-ampere characteristic of resistor QA22 under steep wave and lightning wave in embodiment 1;

Fig. 5 is the voltage and current waveform diagram of resistor sheet RB41 under 4kA steep wave front current in embodiment 2;

Fig. 6 is a comparison diagram of the valve volt-ampere characteristics of the resistor RB41 in embodiment 2 under steep waves and lightning waves.

Detailed ways

In the following, in conjunction with the accompanying drawings and specific examples, the test device for the response characteristics of metal oxide samples under steep front pulses of the present invention will be further described in detail, so as to provide basic data for establishing high-frequency simulation models of arresters under steep waves. The same or similar reference numerals represent the same or similar devices.

As shown in Figure 1-2, the test device includes a steep front current pulse generating device and a test instrument, wherein,

The device for generating steep front current pulses includes a three-electrode switch K and two capacitors (namely the first capacitor C1 and the second capacitor C2), and the two capacitors C1 and C2 respectively have three terminals (namely the first terminal 1, The second terminal 2 and the third terminal 3), the second terminal 2 and the third terminal 3 are equipotential, and are the high-voltage terminals of the two capacitors; the first terminal 1 is independent, and is the two capacitors the low voltage side.

The two capacitors C1 and C2 can be packaged in a thin-film oil-plastic case. Compared with gas-insulated capacitors, their capacity is twice as large at the same size, and the storage, transportation and use of the capacitors have relatively loose environmental requirements. In order to improve the stability and reliability of the test device, the second terminal 2 of the first capacitor C1 can be connected to the positive pole of the DC high voltage power supply through a 1M Ω protection resistor, and the second terminal 2 of the second capacitor C2 can be connected through a 1M Ω The protective resistor is connected to the negative pole of the DC high voltage power supply. The two capacitors C1, C2 and the three-electrode switch K are installed into a compact integrated structure, which can be placed in the transformer oil to improve the breakdown of the switch gap K; the voltage three-electrode switch K can use a three-electrode field distortion gas switch, which can be used External trigger breakdown or self-breakdown, the specific structure of the switch K includes a cylindrical dry gas tank, a trigger electrode packaged in the dry gas tank, and positive and negative high-voltage electrodes located on both sides of the trigger electrode; one of the positive and negative high-voltage electrodes An M10 connecting screw with a length of 0.5cm is installed on each side, and the third terminals 3 of the two capacitors C1 and C2 are respectively provided with M10 screw holes matching the connecting screw, and the connecting screw passes through the through hole on the dry gas tank And screw it into the screw hole to complete the integrated connection of the two capacitors C1, C2 and the three-electrode switch K. Because the connecting screw rod and the screw hole are directly screwed together, the contact is good and there is no need for lead connection, the characteristics of miniaturization and compactness are maximized. The embodiment, can guarantee the loop inductance reaches the minimum. The three-electrode switch uses a dry gas tank as the shell, which has high mechanical strength and can withstand high air pressure, thereby allowing the length of the three-electrode switch to be reduced and the inductance of the switch to be reduced; the dry gas tank is also filled with an insulating gas medium. The insulating gas medium can be air, SF6 gas or other inert gas. The gas pressure range is -0.1MPa～0.1MPa, which can be adjusted continuously. The selected insulating medium and gas pressure depend on the measured current peak value.

An M10 screw is also installed on the second capacitor C2. One end of the screw is screwed on the first terminal 1 of the second capacitor C2, and the other end is connected with two copper strips, the first of which is used to ground the discharge circuit, and the second is used to ground the discharge circuit. The two strips are connected to the crimping piece at one end of the metal oxide sample (referred to as the MOA sample), and the crimping piece at the other end of the MOA sample is connected to the first terminal 1 of the first capacitor C1 through the third copper strip , forming a discharge circuit. The wiring principle of the second and third copper strips above is: under the condition of ensuring that the capacitor does not flashover along the surface, the copper strips should be as short as possible; the surfaces of the copper strips and the two capacitors C1 and C2 are respectively covered with insulating rubber, and the copper strips Wrapped on the surface of the two capacitors C1 and C2, and as close as possible, can ensure that the entire circuit is the most compact and the current front is the steepest. The crimping parts at both ends of the test product are flat cylinders made of two pieces of red copper, which can ensure that the MOA test product is evenly stressed and in good contact, and is convenient for voltage measurement wiring. The above copper strips can be well connected with short and wide copper strips to reduce current oscillation.

The voltage and current testing equipment includes Rogowski coils, high-voltage probes, oscilloscopes and several shielded cables. The Rogowski coils are set on the screw near the grounding copper strip, and the steep front current waveform output by the steep front current pulse generator is transmitted through the shielded cables. To the oscilloscope; under the steep front current waveform, measure the current and voltage waveform of the MOA test product through the high-voltage probe connected to the crimping parts at both ends of the MOA test product, and transmit it to the oscilloscope through the shielded cable. According to the current and voltage waveforms Obtain the response characteristics of the test object under the steep front current waveform.

The specific operation method of the test device is as follows:

The MOA test sample is connected to the loop formed by the steep wave front current pulse generator, and the two capacitors C ₁ and C ₂ of the steep wave front current pulse generator are charged by the DC power supply U so that the three-electrode switch K breaks down and a wave is generated. The rise time of the head is 50~100ns, the peak value is 500A~50kA steep front current waveform, record the current and voltage waveforms on the MOA test product, and read the value corresponding to the flat part after the peak value of the voltage waveform as the residual voltage of the MOA test product . Under the current waveform of the same amplitude, the rise time error of the wave head is ±5ns. Repeat the measurement of the current and residual voltage of the MOA test product 3 times, and each MOA test product measures the residual voltage at no less than 5 different current amplitudes. Using methods such as interpolation and fitting to process the data of the measurement results of the volt-ampere characteristics of the MOA sample, and obtain the average volt-ampere characteristics of the MOA sample under the steep front current pulse.

Example 1

The MOA sample that adopts in an embodiment of the present invention is MOA resistive sheet QA22, and this example is to measure the volt-ampere characteristic of resistive sheet QA22 under the steep wave, and two capacitors C ₁ , C of the steep wave front current pulse generating device The capacitance value of ₂ is 40nF, the three-electrode switch K filled with SF ₆ gas is selected, the gap distance is about 4mm, the gas pressure is -0.1MPa~0.1MPa, and the charging voltage of the DC power supply U is 10kV~100kV. The steep wave front current pulse generating device is placed in the air, and the resistor sheet QA22 is connected to the circuit as shown in Figure 1. The current and voltage waveforms on the resistor sheet are shown in Figure 3. The current is an attenuating oscillatory wave with a period of about 336ns, and the wave head rises The time is 80ns.

By changing the charging voltage of the DC power supply U, the generated current ranges from 610A to 10kA, measured the current and residual voltage values of the resistor QA22 at 10 different current amplitudes, and repeated the measurement for each current amplitude 3 times to obtain the average The value, the current peak value and residual voltage measured on the resistor sheet QA22 are listed in Table 1.

Table 1 Current and residual voltage value of resistor sheet QA22

serial number Current peak (kA) Residual voltage of resistor sheet (kV) 1 0.61 8.2 2 0.98 8.7 3 2.2 8.9 4 3.18 9.16 5 4.8 9.35 6 5.64 9.6 7 6.04 9.84 8 7.8 10.3 9 8.56 10.5 10 10 10.6

Use data processing methods such as interpolation and fitting to process data on the volt-ampere characteristics of the resistor QA22 under steep waves, and compare it with its volt-ampere characteristics under 8/20μs standard lightning waves, as shown in Figure 4. It can be seen that the average volt-ampere characteristics of the resistor under steep waves are basically similar to those under standard lightning waves. As the current increases, the residual voltage of the resistor rises slightly, and the residual voltage of the valve under steep waves increases. more than 20%.

Example 2

The MOA sample that adopts in another embodiment of the present invention is MOA resistive sheet RB41, and this example is to measure the volt-ampere characteristic of MOA resistive sheet RB41 under the steep wave, two capacitors C ₁ of steep wave front current pulse generating device The capacitance values of C _{and C2} are both 40nF, the three-electrode switch K filled with air is selected, the gap distance is about 1mm, the gas pressure is -0.1MPa~0.1MPa, and the charging voltage of the DC power supply U is 10kV~50kV. The steep wave front current pulse generating device is placed in the air, and the resistor sheet RB41 is connected to the circuit as shown in Figure 1. The current and voltage waveforms on the resistor sheet are shown in Figure 5. The current is an attenuating oscillatory wave with a period of about 283ns, and the wave head rises The time is 60ns.

By changing the charging voltage of the DC power supply U, the generated current ranges from 770A to 5.55kA, and the current and residual voltage values of the resistor RB41 at 10 different current amplitudes are measured, and the measurement is repeated 3 times for each current amplitude to obtain The average value, current peak value and residual voltage measured on resistor sheet RB41 are listed in Table 2.

Table 2 Current and Residual Voltage of Resistor RB41

serial number Current peak (kA) Residual voltage of resistor sheet (kV) 1 0.77 14.17 2 0.82 14.47 3 1.33 15.5 4 2.15 15.5 5 2.61 16.03 6 3.48 16.27 7 4.06 16.37 8 4.22 16.57 9 5.34 16.68 10 5.55 16.83

Use data processing methods such as interpolation and fitting to process the volt-ampere characteristics of the resistor RB41 under steep waves, and compare it with the volt-ampere characteristics of the resistor under other waveforms, as shown in Figure 6. Compared with the residual pressure of the valve plate, the residual pressure of the valve plate has increased by about 15%.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. The present invention has been described in detail in conjunction with the above embodiments, and those of ordinary skill in the art should understand that: Modifications or equivalent replacements can be made to the specific embodiments of the present invention, but these modifications or changes are within the protection scope of the pending claims.

Claims (9)

1. metal oxide test product response characteristics testing device under steep pulse is characterized in that, this device comprises:

Steep wave front current impulse generation device links to each other with test product, for generation of the steep wave front current waveform; With

Testing tool links to each other with test product, is used for measuring electric current, the voltage waveform of test product;

Described steep wave front current impulse generation device comprises successively the first capacitor of series connection, three electrode switch and the second capacitor, be equipped with three terminals on described the first capacitor and the second capacitor, the second terminals of described the first capacitor and the second capacitor just are being connected to power supply by 1M Ω resistance respectively, negative pole, carry out integrated the connection by three electrode switch between the 3rd terminals of described the first capacitor and the second capacitor, described the first capacitor links to each other with the crimp that is installed in the test product two ends by copper strips respectively with the first terminals of the second capacitor, consists of discharge loop.

2. proving installation according to claim 1 is characterized in that: on the first terminals of described the second capacitor screw rod is installed, the free time end of this screw rod is equipped with for the copper strips that connects test product and is used for making the ground connection copper strips of discharge loop ground connection.

3. proving installation according to claim 2, it is characterized in that: described testing tool comprises the Luo-coil that is sheathed on the screw rod, the high-voltage probe, shielded cable and the oscillograph that are connected with the crimp at test product two ends; Described Luo-coil reaches oscillograph with the steep wave front current waveform of steep wave front current impulse generation device output through shielded cable; Under described steep wave front current waveform, described high-voltage probe is measured electric current, the voltage waveform of test product, and reaches oscillograph through shielded cable.

4. arbitrary described proving installation is characterized in that according to claim 1-3, and the concrete structure of described integrated connection is:

Described three electrode switch comprise dry gas tank and the positive and negative high-field electrode that is packaged in the trigger electrode in the dry gas tank and is positioned at the trigger electrode both sides, one side of described positive and negative high-field electrode is respectively equipped with connecting screw rod, be respectively equipped with the screw that is complementary with connecting screw rod on the 3rd terminals of described the first capacitor and the second capacitor, described connecting screw rod screws in realizes in the screw that the first capacitor, the second capacitor are connected with the integrated of three electrode switch; Be filled with the insulating gas medium in the described dry gas tank.

5. proving installation according to claim 4, it is characterized in that: described insulating gas medium is air, SF6 gas or other inert gas.

6. arbitrary described proving installation is characterized in that: the oblate column structure that described crimp adopts conductive material to make according to claim 1-3.

7. arbitrary described proving installation according to claim 1-3, it is characterized in that: described the first terminals are the low pressure end of the first capacitor and the second capacitor; Described the second terminals and the 3rd terminals are equipotential, are the high-pressure side of the first capacitor and the second capacitor.

8. arbitrary described proving installation according to claim 1-3, it is characterized in that: the first terminals of described the first capacitor and the 3rd terminals lay respectively at the relative both sides of housing of the first capacitor, the second terminals plugged of described the first capacitor is anodal, and it is located on the first capacitor casing of a side adjacent with the 3rd terminals; The first terminals of described the second capacitor and third high pressure side are positioned at the relative both sides of housing of the second capacitor, the second terminals plugged negative pole of described the second capacitor, and it is located on the second capacitor casing of a side adjacent with the 3rd terminals.

9. arbitrary described proving installation according to claim 1-3, it is characterized in that: the first terminals of described connection the first capacitor fill up respectively with the surface of copper strips, the first capacitor and second capacitor of the copper strips of test product one end, the first terminals that are connected the second capacitor and the test product other end and are provided with insulation rubber, and above-mentioned two copper strips are wound in respectively the surface of the first capacitor and the second capacitor.

Images