High-voltage direct-current line EM lightning arrester valve plate shunting non-uniformity test system and method

Abstract

The invention discloses a high-voltage direct-current line EM lightning arrester valve plate shunting non-uniformity test system and method, and belongs to the technical field of lightning arrester performance test.The method comprises the steps that S1, a high-voltage direct-current power transmission system simulation model is established, and the discharge current of an EM lightning arrester under the severe working condition of single-pole line short circuit is evaluated based on the high-voltage direct-current power transmission system simulation model; adopting square-wave pulse approximate discharge current, and determining the total amplitude and square-wave pulse width of long-wave discharge current of the EM lightning arrester; s2, applying the square wave pulse to the tested EM lightning arrester resistor discs through a shock wave test platform, and testing the current magnitude and the total current of each resistor disc of the EM lightning arrester under the working condition; the total amplitude and the square wave pulse width of the preset square wave pulse are the same as the total amplitude and the square wave pulse width of the long wave of the discharge current of the EM arrester; and S3, according to the current of each resistor disc and the total current, calculating a current non-uniform coefficient and the current range of the resistor discs. According to the invention, the current distribution non-uniformity of the multi-column parallel lightning arrester can be tested and evaluated more reasonably and comprehensively.

Description

Technical Field

[0001] The present invention belongs to the technical field of arrester performance testing, and specifically relates to an evaluation index, a test system and a test method for the shunt non-uniformity of the valve plates of an EM arrester for a high-voltage DC line. Background Art

[0002] An EM arrester, i.e., a metallic return line arrester, is a device used to protect DC power system equipment from lightning strikes. When an EM arrester is struck by lightning, it will absorb a huge current. Therefore, a multi-column parallel electrical combination method is usually adopted to prevent it from being damaged due to excessive energy. The shunt non-uniformity of a multi-column parallel arrester may be caused by various factors, including the structural design of the arrester, external environmental conditions, electrical connections between arrester columns, etc. Non-uniformity may cause a larger voltage gradient in some columns, making them bear a greater current. Therefore, the study of the current non-uniformity of a multi-column parallel arrester is very important. In Chinese national standards such as GB11032-2020: "AC Non-Current-Carrying Metal Oxide Arrester" and GB / T22389-2008: "Guide for Non-Current-Carrying Metal Oxide Arrester in HVDC Converter Stations", the current non-uniformity is quantified as an index, and it is considered that the non-uniformity coefficient β of the current distribution between the columns of multi-column resistive elements should not be greater than 1.1. However, in fact, the operating conditions of EM arresters vary greatly, and this index cannot reasonably evaluate the non-uniformity of arresters.

[0003] Previously, in the academic field, the research direction of the shunt non-uniformity of multi-column parallel arresters mostly focused on the consequences brought by non-uniformity, which factors would increase the non-uniformity coefficient, and how to optimize the design to reduce non-uniformity. Chen Xilei et al. theoretically analyzed the energy absorption capacity of an arrester considering the non-uniform current distribution characteristics. First, they analyzed the influence of the deviation of the arrester volt-ampere characteristics on the current distribution, gave the definition of the non-uniformity coefficient of the current distribution, and derived in detail the energy absorption capacity of a multi-column parallel arrester under non-uniform current distribution, and gave the formula for calculating the energy absorption capacity. Finally, through analysis, it was concluded that a slight deviation in the volt-ampere characteristics of the resistive element would cause a large non-uniformity in the arrester current distribution, and the non-uniform current distribution would reduce the energy absorption capacity of the entire arrester. Therefore, in order to achieve the purpose of equal current sharing among columns, the residual voltage deviation of the resistive element should be controlled not to exceed 1%. This research provides great reference for the design of arresters and the overvoltage and insulation coordination of DC transmission systems. However, its research is still based on the basis that the non-uniformity coefficient cannot exceed 1.1, and the obtained results have a large range. Moreover, there is a large difference between the actual operating conditions of arresters and the theory, and there may be a situation where the margin is insufficient and the arrester is damaged. If the arrester operates for too long, it may cause the occurrence of "short pieces", which will damage the arrester, especially for lines in areas with frequent lightning strikes, this problem is particularly prominent.

[0004] Therefore, relying solely on national standard indicators often fails to comprehensively and accurately evaluate the current non-uniformity of surge arresters. In actual situations, surge arresters may face sudden high-current shocks, which can lead to temporary changes in current distribution non-uniformity, and national standard indicators cannot fully reflect the impact of this temporary non-uniformity. Therefore, more detailed and comprehensive research methods are needed to more accurately evaluate the current non-uniformity of surge arresters. Summary of the Invention

[0005] The present invention provides a test system and method for the shunt non-uniformity of EM arrester valve plates in high-voltage DC transmission lines to more reasonably and comprehensively test and evaluate the current distribution non-uniformity of multi-column parallel surge arresters.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A test method for the shunt non-uniformity of EM arrester valve plates in high-voltage DC transmission lines includes:

[0008] S1. Establish a simulation model of a high-voltage DC power transmission system, evaluate the discharge current of the EM arrester under the severe condition of single-pole line short circuit based on the simulation model of the high-voltage DC power transmission system, approximate the discharge current with a square-wave pulse, and determine the total amplitude and square-wave pulse width of the long-wave discharge current of the EM arrester.

[0009] S2. Apply the square-wave pulse to the resistor plates of the EM arrester to be tested, and measure the current magnitude of each column of resistor plates and the total current of the arrester under this condition; the total amplitude and square-wave pulse width of the square-wave pulse are the same as the total amplitude and square-wave pulse width of the long-wave discharge current of the EM arrester.

[0010] S3. Calculate the current non-uniformity coefficient and the range of the resistor plate current according to the current of each column of resistor plates and the total current.

[0011] Further, in step S1, when establishing the simulation model of the high-voltage DC power transmission system, each column of resistor plates of the EM arrester is simulated as a separate component.

[0012] Further, step S2 includes the following steps:

[0013] S2.1. Screen the resistor plates through DC parameter measurement, shock wave residual voltage test, full current, resistive current, capacitive current, and dielectric constant test of the resistor plates.

[0014] S2.2. Calibrate all current loops of the shock wave test platform, and perform the next step when the results of all current loops are consistent.

[0015] S2.3. Select the filtered resistor chips, group the resistor chips, and then put all the resistor chips in the same group into the shock wave test platform, apply a square wave pulse, and record the current flowing through each column of resistor chips, the residual voltage, and the total current of the arrester under the square wave pulse.

[0016] Further, in step S2.3, group the resistor chips according to the 1 mA DC reference voltage and the capacitance difference at a charging rate of 80%.

[0017] Further, in step S2.3, after obtaining the residual voltage and the total current, obtain the volt-ampere characteristic curve of the arrester according to the residual voltage and the total current of the arrester.

[0018] Further, in step S3, the range is: the quotient of the difference between the maximum value and the minimum value of the current in each parallel column and the average value of the current in each column.

[0019] Further, use the range of the resistor chip current as the evaluation criterion for the shunt non-uniformity.

[0020] A test system for the shunt non-uniformity of the valve chips of a high-voltage DC line EM arrester includes:

[0021] A simulation module for constructing a high-voltage DC power transmission system including EM arrester valve chips and obtaining preset square wave pulse parameters based on the high-voltage DC power transmission system;

[0022] A shock wave test platform for testing the current of each column of resistor chips of the EM arrester and the total current of the arrester under this working condition by applying a preset square wave pulse;

[0023] A calculation module for calculating the current non-uniformity coefficient and the range according to the current of each column of resistor chips and the total current of the arrester.

[0024] Further, the shock wave test platform includes a transformer T. The primary winding of the transformer T is connected to a power supply, and the secondary winding, a diode D, and a resistor R1 are connected in series and then connected in parallel with a switch branch. One end of the switch branch is connected to a sphere gap discharge device G, and the other end is used to connect the resistor chip under test.

[0025] Further, the switch branch is connected in parallel with a capacitor C.

[0026] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0027] The present invention aims at a high-voltage DC power transmission system, establishes an overvoltage calculation model, simulates the overvoltage waveform of an EM lightning arrester, uses a square wave close to the overvoltage waveform as the test waveform for testing, and uses the actual calculation result as the guidance for the current amplitude; the present invention also establishes a test platform for multi-column parallel lightning arresters, measures the multi-column current, and finally determines the method of using the current non-uniformity coefficient and the current range as evaluation indicators through analysis. This indicator provides a more reliable basis for the design optimization and performance improvement of lightning arresters.

[0028] The present invention proposes that on the basis that the current distribution non-uniformity coefficient β is less than 1.1, the current range of each column is used as a characterization index, and the test method for the current range of the EM lightning arrester is specified, providing a more reasonable and stringent index for the design of multi-column parallel lightning arresters, and further ensuring the reliable operation of the lightning arrester.

[0029] Furthermore, approximating the discharge current with a square wave pulse is based on the result of actual overvoltage analysis and is a non-uniform test result that conforms to the actual operating state of the EM lightning arrester. Conducting tests on this basis can make the test results more accurate and also provide a basis for the subsequent proposal of evaluation indicators for the non-uniformity of the lightning arrester current distribution.

[0030] The calculation of the current range is simple, and as the current range increases, the maximum energy of a single column and the current generally show an increasing trend. Therefore, on the basis of the shunt non-uniformity coefficient, the discharge current range between columns can characterize the extreme energy absorption difference of the EM lightning arrester. When the shunt non-uniformity coefficient of the EM lightning arrester meets the national standard requirement of <1.1 and the residual is not effectively controlled, it may lead to significantly larger energy absorption of a single column, accelerating the deterioration of the valve pieces inside the column, and the cumulative effect may cause the generation of short pieces; after the appearance of aging short pieces, the energy absorption of a single column increases significantly, and it is calculated that it can exceed its tolerance limit under a short-circuit fault, resulting in the thermal breakdown and cracking of the lightning arrester. Therefore, on the basis that the shunt non-uniformity coefficient meets the national standard requirements, the present invention proposes to use the current non-uniform range as a further evaluation indicator.

[0031] The present invention gives the specific test method and steps for the volt-ampere characteristics of the resistor chips under long-wave excitation of multi-column parallel lightning arresters. The test operation method is simple and has wide applicability. Brief Description of the Drawings

[0032] Figure 1 is the main circuit of the ±800 kV UHV DC power transmission system built by the present invention;

[0033] Figure 2a is the transmission line model of the ±800 kV UHV DC power transmission system built by the present invention;

[0034] Figure 2b is the circuit model of the multi-column parallel lightning arrester built by the present invention;

[0035] Figure 3 It is the circuit structure diagram of the shock wave test platform built by the present invention, which can not only be used for the screening of resistor chips, but also meet the requirements of the overvoltage square wave waveform needed for testing in the future;

[0036] Figure 4 It is the discharge current waveform diagram of the EM lightning arrester under the severe condition of single-pole line short circuit;

[0037] Figure 5 It is the DC parameter measurement test platform. The resistor chip to be measured is placed in the electrode, and the output current is adjusted by rotating the button. The device automatically displays the reference voltage. Whether the selected resistor chip meets the requirements is explored according to whether the reference voltage exceeds a 5% change;

[0038] Figure 6 It is the current loop calibration diagram; The EM lightning arrester is a multi-column parallel structure. Before the formal test of the multi-columns, the four current loops are calibrated to make their measurement results consistent. The four current loops are connected in series and respectively connected to the four ports of the oscilloscope to ensure the consistency of the results of the four current loops.

[0039] Figure 7 It is the calibrated measurement result;

[0040] Figure 8 It is the multi-column parallel connection diagram;

[0041] Figure 9 It is the relationship between the maximum current of a single column and the current range;

[0042] Figure 10 It is the relationship between the maximum energy of a single column and the current range. Detailed implementation manner

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific implementation manners.

[0044] In order to enable those skilled in the art of the present technology to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0045] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be another element in the middle. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be another element in the middle at the same time. The orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. used in this article is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used in this article have the same meaning as those commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0047] Referring to Figure 1 , a method for testing the shunt non-uniformity of the valve disc of a high-voltage DC line EM lightning arrester includes the following steps:

[0048] S1. Establish a Figure 1 , Figure 2a and Figure 2b simulation model of the ±800 kV UHV DC transmission system shown in the figure, evaluate the discharge current of the EM lightning arrester under the severe condition of single-pole line short circuit, approximate the discharge current with a square-wave pulse, and determine the total amplitude and square-wave pulse width of the long wave of the discharge current released by the EM lightning arrester;

[0049] S2. Establish a Figure 3 shock wave test platform shown in the figure, select the number of resistor chips according to the test capacity of the platform, group the resistor chips that have been screened, and try to increase the number of parallel columns of the valve discs of the lightning arrester within the allowable range of the test capacity. Calculate the number of parallel columns and the number of resistor chips in a single column, calibrate the current loop, and apply a preset square-wave pulse to the valve discs of the lightning arrester. The number of pulses received by a single column is close to that of the simulation, and the error does not exceed 20%.

[0050] S3. Collect test data, calculate the current non-uniformity coefficient and the range according to the test data, and complete the evaluation of the shunt non-uniformity.

[0051] The ±800 kV UHV DC transmission system simulation model built in step S1 is as shown in Figure 1 , Figure 2a and Figure 2b, the ±800kV UHVDC transmission system simulation model (hereinafter referred to as the simulation) includes the following parts:

[0052] 1) Converter. The converter is the core component of DC transmission, realizing the conversion from AC to DC and from DC to AC.

[0053] 2) Converter transformer. In the DC transmission system, the converter transformer regulates the voltage of the AC system, serves as the input of the converter, and at the same time undertakes functions such as AC-DC electrical isolation, suppressing lightning overvoltage, and suppressing the cross-domain propagation of fault current.

[0054] 3) DC filter. The DC filter is set at the outlet of the converter station, in parallel with the DC transmission line. Through impedance matching, it has low impedance characteristics at certain frequencies, thereby filtering the current of specific frequencies and playing a role in suppressing harmonic current from entering the DC line.

[0055] 4) AC filter. The AC filter is set between the AC system and the converter transformer, in parallel with the AC system bus. Through impedance design, it realizes low-resistance filtering characteristics for certain frequencies. Compared with the DC filter, in addition to suppressing the harmonic current in the converter from entering and interfering with the AC system, it also has the function of reactive power compensation.

[0056] 5) Smoothing reactor. The smoothing reactor is set between the DC converter and the DC transmission line. Its main function is to make the DC current more stable, reduce the harmonic voltage and current of the DC line, and at the same time also has the function of reducing the probability of inverter commutation failure and limiting the short-circuit current.

[0057] 6) DC overhead line. The DC overhead line is the transmission line connecting the rectifier station and the inverter station.

[0058] 7) Modeling of multi-column parallel arrester circuit. For the convenience of simulating the non-uniformity, each column of the EM arrester is used as a separate element for simulation, so the EM arrester model is composed of multi-column parallel nonlinear resistors outside the core body.

[0059] In this simulation model, simulate the severe condition of single-pole line short circuit, and obtain the overvoltage, discharge current and energy absorption of the EM arrester under this condition. The discharge current of the EM arrester under the severe condition of single-pole line short circuit is approximately a sine wave. As Figure 4 shown, for the convenience of the experiment, a square wave pulse approximation is adopted. The pulse width and amplitude of the square wave pulse are determined according to the pulse width and amplitude of the discharge current sine wave. The square wave pulse width is the same as that of the sine wave, and the amplitude is determined according to the area enclosed by the horizontal and vertical axes of the square wave being the same as the area enclosed by the horizontal and vertical axes of the sine wave. Determine the total amplitude and square wave pulse width of the square wave pulse approximating the long wave of the EM arrester discharge current; the amplitude is 400A and the square wave pulse width is 20ms.

[0060] In step S2, the established multi-column parallel shock wave experimental test platform is as Figure 3 shown. This test platform can be used for the screening of resistor chips.

[0061] The multi-column parallel test platform includes a transformer T. The primary winding of the transformer T is connected to the power supply. The first end of the secondary winding is connected to the anode of the diode D, and the cathode of the diode D is connected to the first end of the resistor R1. The second end of the resistor R1 is connected to the first end of the resistor R2, the first end of the capacitor C, and the first end of the sphere gap discharge device G. The second end of the resistor R2 is connected to the first end of the switch S. The second end of the switch S and the second end of the capacitor C are grounded. The second end of the sphere gap discharge device G is connected to the first end of the multi-column parallel resistor chip, and the second end of the multi-column parallel resistor chip is grounded. The multi-column parallel resistor chip includes four parallel resistors R. Among them, the function of the diode D is rectification. The resistors R1 and R2 are protective resistors, which are used to protect the circuit and the diode D and have the function of voltage stabilization at the same time. The capacitor C can play a filtering role.

[0062] When using the multi-column parallel shock wave experimental test platform for resistor chip screening, the shock wave test platform mainly includes an AC high-voltage test power supply, a voltage regulator, a transformer, a protective resistor, and a pair of spherical electrodes with the same diameter. The measurement principle is sphere gap discharge, and the measurement result is the peak value of the impulse voltage.

[0063] When using the multi-column parallel shock wave experimental test platform for resistor chip screening, the multi-column resistor chips are connected in parallel to the shock wave test equipment, and the 30 / 60 us operating residual voltage test and the 8 / 20 us lightning residual voltage test are carried out respectively. The resistor chips that are punctured, perforated, or fragmented are removed, and the shunt current of each column of resistor chips is measured and recorded to evaluate the shunt non-uniformity between columns.

[0064] Using the approximate square wave pulse determined in step S1 as the test excitation wave, the volt-ampere characteristics test of the resistor chip is carried out. The steps for the volt-ampere characteristics test of the resistor chip under the long-wave excitation of the multi-column parallel lightning arrester are as follows:

[0065] S2.1. Resistor chip screening. Basic screening of the resistor chips is carried out through DC parameter measurement, shock wave residual voltage test, full current, resistive current, capacitive current, and dielectric constant test of the resistor chips. The resistor chips after screening are used to further carry out the analysis of the non-uniformity coefficient. Among them, the DC parameter measurement is carried out through the Figure 5 shown DC parameter measurement test platform.

[0066] S2.2. Calibration of the measurement system of the shock wave experimental test platform. Before the formal test, according to Figure 6The current loop is calibrated as shown to ensure consistent measurement results of the current loop. The volt-ampere (V-A) characteristics of a single resistor chip are measured, and four current loops are connected in series and respectively connected to four ports of an oscilloscope. The test results are as Figure 7 shown. It can be found that the results of the four current loops are consistent. This indicates compliance with the test standards and allows for the formal test to be carried out.

[0067] S2.3. Formal test of resistor chip grouping. Twenty resistor chips after basic screening are selected. According to the 1 mA DC reference voltage and the capacitance difference at a charge rate of 80%, the resistor chips are grouped. Considering the experimental capabilities, multi-column single chips are selected, and the resistor chips are grouped into multi-column parallel combinations. Then, 4 resistor chips in the same group are placed in the shock wave test platform, Figure 8 which is a schematic diagram of multi-column resistor chips in parallel. A preset square wave pulse is applied to obtain the test results, namely, the current magnitude flowing through each column of resistor chips, the residual voltage, and the total current under a 20 ms approximate square wave pulse excitation.

[0068] S2.4. Data statistics and analysis. Record the current magnitude flowing through each column of resistor chips, the residual voltage, and the total current under a 20 ms approximate square wave pulse excitation. According to the residual voltage and the total current, the volt-ampere characteristic curve of the arrester can be obtained; according to the definition of the non-uniformity coefficient, calculate the non-uniformity coefficient of each group of data, and calculate the range of the non-uniformity coefficient, and analyze the relationship between the range and the maximum absorption energy of a single column of the arrester. The maximum absorption energy of a single column of the arrester is obtained through simulation calculation.

[0069] The test results are shown in Table 1. The data in Table 1 are the test results, the calculated current non-uniformity coefficient, and the range, for a total of five groups of data.

[0070] Table 1 Relationship between current range and single-column load

[0071] Group number Maximum current / kA Maximum absorbed energy / MJ Non-uniformity coefficient Range 1 0.362 4.296 1.114 0.283 2 0.382 4.538 1.178 0.404 3 0.375 4.349 1.131 0.357 4 0.375 4.393 1.141 0.382 5 0.368 4.420 1.150 0.302

[0072] The non-uniformity coefficient and the range are calculated respectively. According to GB / T 11032-2020 "AC Non-gap Metal Oxide Surge Arresters", the non-uniformity coefficient of the multi-column parallel arrester is calculated, and its definition is:

[0073]

[0074] In the formula: β is the non-uniformity coefficient; n is the number of parallel columns; I max is the maximum current peak value passing through the resistor chip column or arrester element, in amperes (A); I arr is the total current passing through the arrester, in amperes (A).

[0075] The calculation method of the range is:

[0076]

[0077] where: γ is the non-uniformity coefficient; I max is the maximum current peak passing through the resistor column or arrester element, with the unit of ampere (A); I min is the minimum current peak passing through the resistor column or arrester element, with the unit of ampere (A).

[0078] For the EM arrester used in the ±800 kV DC system, it is advisable to control the current difference index < 0.3.

[0079] The relationship between the difference and the maximum current and maximum energy of a single column is represented by a line graph. From Figure 9 and 10 , we can see that as the current difference increases, the maximum energy of a single column and the current generally show an increasing trend. By expanding the current coefficient range, it can also be found that as the difference increases, the current and energy borne by a single column gradually increase. Therefore, the difference can be used to describe the load characteristics of the resistor chip.

[0080] The term "comprising" used to describe a combination shall include the identified elements, components, parts or steps and other elements, components, parts or steps that do not substantially affect the basic novel features of the combination. Using the terms "including" or "comprising" to describe the combination of elements, components, parts or steps here also contemplates embodiments consisting essentially of these elements, components, parts or steps. By using the term "may" here, it is intended to indicate that any attribute described as "may" included is optional.

[0081] Multiple elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step can be divided into multiple separate elements, components, parts or steps. The disclosure of "a" or "an" used to describe an element, component, part or step does not mean to exclude other elements, components, parts or steps.

[0082] It should be understood that the above description is for illustrative purposes and not for limitation. By reading the above description, many embodiments and many applications other than the provided examples will be obvious to those skilled in the art. Therefore, the scope of this teaching should not be determined with reference to the above description, but should be determined with reference to the full scope of the foregoing claims and the equivalents of these claims. For the sake of completeness, all articles and references including patent applications and published announcements are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to abandon such subject matter, nor should the applicant be considered not to have considered such subject matter as part of the disclosed inventive subject matter.

Claims

1. A test method for the non-uniformity of shunt current of the valve disc of a high-voltage DC line EM lightning arrester, characterized in that, Including: S1. Establish a simulation model of a high-voltage direct current (HVDC) transmission system. Based on the HVDC transmission system simulation model, evaluate the discharge current of the EM arrester under the severe condition of a monopole line short circuit. Approximate the discharge current with a square-wave pulse, and determine the total amplitude and square-wave pulse width of the long-wave discharge current of the EM arrester. S2. Apply the square-wave pulse to the resistor chips of the EM arrester under test, and measure the current of each column of resistor chips and the total current of the arrester under this condition. The total amplitude and square-wave pulse width of the square-wave pulse are the same as those of the long-wave of the discharge current of the EM arrester. S3. Calculate the current unevenness coefficient and the range of the resistor chip current according to the current of each column of resistor chips and the total current.

2. The method for testing the shunt non-uniformity of the valve disc of the HVDC line EM lightning arrester according to claim 1, characterized in that, In step S1, when establishing the HVDC transmission system simulation model, each column of resistor chips of the EM arrester is simulated as an independent component.

3. The method for testing the uneven shunt of the valve disc of the HVDC line EM lightning arrester according to claim 1, wherein Step S2 includes the following steps: S2.

1. Screen the resistor chips through DC parameter measurement, impulse residual voltage test, full current of the resistor chip, resistive current, capacitive current, and permittivity test. S2.

2. Calibrate all current loops of the impulse test platform. When the results of all current loops are consistent, proceed to the next step. S2.

3. Select the screened resistor chips, group the resistor chips, and then place all the resistor chips in the same group into the impulse test platform, apply a square-wave pulse, and record the current flowing through each column of resistor chips, the residual voltage, and the total current of the arrester under the square-wave pulse.

4. The method for testing the uneven shunt of the valve disc of the HVDC line EM lightning arrester according to claim 3, characterized in that, In step S2.3, the resistor chips are grouped according to the 1 mA DC reference voltage and the capacitance difference at a charging rate of 80%.

5. The method for testing the uneven shunt of the valve disc of the HVDC line EM lightning arrester according to claim 3, characterized in that, In step S2.3, after obtaining the residual voltage and the total current, obtain the volt-ampere characteristic curve of the arrester according to the residual voltage and the total current of the arrester.

6. The method for testing the uneven shunt of the valve plate of the HVDC line EM lightning arrester according to claim 1, wherein In step S3, the range is: the quotient of the difference between the maximum current and the minimum current in parallel columns divided by the average current of each column.

7. The method for testing the uneven shunt of the valve disc of the HVDC line EM lightning arrester according to claim 1, characterized in that Use the range of the resistor chip current as the evaluation criterion for shunt unevenness.

8. A test system for the uneven shunt of a valve disc of a high-voltage DC line EM lightning arrester, characterized in that, Including: A simulation module, used to construct a HVDC transmission system including EM arrester valve chips, and obtain preset square-wave pulse parameters based on the HVDC transmission system. An impulse test platform, used to measure the current of each column of resistor chips and the total current of the EM arrester under this condition by applying a preset square-wave pulse. A calculation module, used to calculate the current unevenness coefficient and the range according to the current of each column of resistor chips and the total current of the arrester.

9. The test system for the uneven current sharing of the valve plates of the HVDC line EM lightning arrester according to claim 8, wherein, The impulse test platform includes a transformer T. The primary winding of the transformer T is connected to a power supply. The secondary winding, a diode D, and a resistor R1 are connected in series and then connected in parallel with a switch branch. One end of the switch branch is connected to a sphere gap discharge device G, and the other end is used to connect the resistor chips under test.

10. The test system for the uneven shunt of the valve disc of the HVDC line EM lightning arrester according to claim 8, wherein, The switch branch is connected in parallel with a capacitor C.

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