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 invention belongs to the field of lightning arrester performance testing, and in particular relates to an evaluation index, a test system and a test method for the valve plate current shunting non-uniformity of an EM lightning arrester in a high-voltage direct current line. Background Art

[0002] EM arrester, or metal return line arrester, is a device used to protect DC power system equipment from lightning strikes. When struck by lightning, EM arresters absorb huge currents, so they usually adopt a multi-column parallel electrical combination to prevent them from being damaged by excessive energy. The uneven current distribution of multi-column parallel arresters may be caused by a variety of factors, including the structural design of the arrester, external environmental conditions, and electrical connections between arrester columns. The unevenness may cause a large voltage gradient in some columns, causing them to bear a larger current. Therefore, the study of the current unevenness of multi-column parallel arresters is very important. The China National Standards Committee GB11032-2020: "AC Gapless Metal Oxide Arrester" China National Standards Committee GB / T22389-2008: "Guidelines for Gapless Metal Oxide Arrester in High-Voltage DC Converter Stations" and other standards use current unevenness as an indicator to quantify it, and believe that the current distribution unevenness coefficient β between the columns of the multi-column resistor should not be greater than 1.1. However, in reality, the operating conditions of EM arresters vary greatly, and this indicator cannot reasonably evaluate the non-uniformity of the arrester.

[0003] Previously, the research directions of the academic community on the uneven current distribution of multi-column parallel arresters were mostly the consequences of unevenness, which factors would increase the unevenness coefficient, and how to optimize the design to reduce unevenness. Chen Xilei and others theoretically analyzed the energy absorption capacity of the arrester after considering the uneven current distribution characteristics. First, they analyzed the influence of the deviation of the arrester's volt-ampere characteristics on the current distribution, and gave the definition of the current distribution unevenness coefficient. They derived the energy absorption capacity of the multi-column parallel arrester under uneven current distribution in detail, and gave the formula for calculating the energy absorption capacity. Finally, after analysis, it was concluded that a slight deviation in the volt-ampere characteristics of the resistor will cause a larger uneven current distribution of the arrester, and the uneven current distribution will reduce the energy absorption capacity of the entire arrester. Therefore, in order to achieve the purpose of equal current distribution in each column, the residual voltage deviation of the resistor should be controlled to not exceed 1%. This study provides a great reference for the design of lightning arresters and the overvoltage and insulation coordination of DC transmission systems. However, the study is based on the premise that the non-uniformity coefficient cannot exceed 1.1. The range of results is large, and the actual working conditions of the lightning arrester are quite different from the theoretical ones. There may be a situation where the margin is insufficient and the lightning arrester is damaged. If the lightning arrester runs for too long, it may cause "dwarf pieces" to occur, which in turn damages the lightning arrester. This problem is particularly prominent for lines in areas with frequent lightning strikes.

[0004] Therefore, relying solely on national standard indicators often cannot fully and accurately evaluate the current non-uniformity of lightning arresters. In actual situations, lightning arresters may face sudden high current shocks, and these shocks may cause temporary changes in current distribution non-uniformity. National standard indicators cannot fully reflect the impact of such temporary non-uniformity. Therefore, a more detailed and comprehensive research method is needed to more accurately evaluate the current non-uniformity of lightning arresters. Summary of the invention

[0005] The present invention provides a high-voltage DC line EM arrester valve plate current shunting non-uniformity testing system and method, so as to more reasonably and comprehensively test and evaluate the current distribution non-uniformity of multi-column parallel arresters.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for testing the current shunting non-uniformity of valve plates of EM arresters of high-voltage direct current lines, comprising:

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

[0009] S2, applying the square wave pulse to the resistor of the EM arrester under test, testing the current of each resistor and the total current of the arrester under the working condition; the total amplitude and pulse width of the square wave pulse are the same as the total amplitude and pulse width of the long wave of the EM arrester discharge current;

[0010] S3. Calculate the current non-uniformity coefficient and the range of the resistor current based on the current of each resistor column and the total current.

[0011] Furthermore, in step S1, when establishing the high voltage direct current transmission system simulation model, each column resistor of the EM arrester is simulated as a separate component.

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

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

[0014] S2.2. Calibrate all current loops of the shock wave test platform. When the results of all current loops are consistent, proceed to the next step.

[0015] S2.3. Select the resistors after screening and group them. Then put all the resistors in the same group into the shock wave test platform, apply square wave pulses, and record the current, residual voltage and total current of the arrester flowing through each column of resistor under the square wave pulse.

[0016] Furthermore, in step S2.3, the resistors are grouped according to the 1 mA DC reference voltage and the capacitance difference of 80% charge rate.

[0017] Furthermore, in step S2.3, after the residual voltage and the total current are obtained, the volt-ampere characteristic curve of the arrester is obtained according to the residual voltage and the total current of the arrester.

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

[0019] Furthermore, the range of the resistor current is used as a criterion for evaluating the current shunting non-uniformity.

[0020] A high voltage DC line EM arrester valve plate current shunting non-uniformity testing system, comprising:

[0021] A simulation module, used for constructing a high-voltage direct current transmission system including an EM arrester valve plate, and obtaining preset square wave pulse parameters based on the high-voltage direct current transmission system;

[0022] The shock wave test platform is used to test the current of each resistor column and the total current of the EM arrester under the working condition by applying a preset square wave pulse;

[0023] The calculation module is used to calculate the current unevenness coefficient and the range according to the current of each resistor column and the total current of the lightning arrester.

[0024] Furthermore, the shock wave test platform includes a transformer T, wherein 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 spherical gap discharge device G, and the other end is used to connect a tested resistor.

[0025] Furthermore, the switch branch and the capacitor C are connected in parallel.

[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 direct current transmission system, establishes an overvoltage calculation model, simulates the overvoltage waveform of an EM arrester, uses a square wave close to the overvoltage waveform as an assessment waveform for testing, and uses actual calculation results as a guide for the current amplitude; the present invention also establishes a multi-column parallel arrester test platform, measures the multi-column current, and finally determines, through analysis, a method of using the current non-uniformity coefficient and the current extreme difference as evaluation indicators, which provides a more reliable basis for the design optimization and performance improvement of the arrester.

[0028] The present invention proposes to use the current extreme difference of each column as a characterization index on the basis that the current distribution uneven coefficient β is less than 1.1, and stipulates a test method for the current extreme difference of EM lightning arrester, which provides more reasonable and stringent indicators for the design of multi-column parallel lightning arresters and further ensures the reliable operation of the lightning arrester.

[0029] Furthermore, the use of square wave pulses to approximate the discharge current is based on the results of actual overvoltage analysis and is consistent with the uneven test results of the actual EM arrester operating state. Testing on this basis can make the test results more accurate and also provide a basis for the subsequent evaluation index of the current distribution unevenness of the arrester.

[0030] The current extreme difference is simple to calculate, and as the current extreme difference increases, the maximum energy and current of a single column generally show an increasing trend. Therefore, on the basis of the shunt unevenness coefficient, the discharge extreme difference between columns can characterize the extreme energy absorption difference of the EM arrester. When the shunt unevenness coefficient of the EM arrester meets the national standard requirement of <1.1, if the residual is not effectively controlled, the energy absorption of a single column will be significantly larger, accelerating the degradation of the valve plate in the column, and the cumulative effect will lead to the generation of short plates; after the aging short plates appear, 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 thermal collapse and cracking of the arrester. Therefore, on the basis that the shunt unevenness coefficient meets the national standard requirements, the present invention proposes to use the current uneven extreme difference as a further evaluation indicator.

[0031] The invention provides a specific method and steps for testing the volt-ampere characteristics of a resistor under long-wave excitation of a multi-column parallel arrester. The test operation method is simple and has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the main circuit of the ±800kV ultra-high voltage direct current transmission system constructed by the present invention;

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

[0034] Figure 2b It is a multi-column parallel arrester circuit model constructed by the present invention;

[0035] Figure 3 This is a circuit diagram of the shock wave test platform constructed by the present invention, which can not only be used to screen resistors, but also meet the overvoltage square wave waveform requirements required for subsequent testing;

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

[0037] Figure 5 It is a DC parameter measurement test platform. Put the resistor to be tested into the electrode, rotate the button to adjust the output current, and the device automatically displays the reference voltage. According to whether the reference voltage changes by more than 5%, it is explored whether the selected resistor meets the requirements;

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

[0039] Figure 7 is the calibration measurement result;

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

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

[0042] Fig.10 It is the relationship between the maximum energy of a single column and the current range. DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] In order to enable those skilled in the art 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. used herein indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are 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 cannot be understood as a limitation on the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention 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 related listed items.

[0047] Reference Figure 1 , a method for testing the non-uniformity of current diversion of valve plates of EM lightning arresters of high-voltage direct current lines, comprising the following steps:

[0048] S1. Establishment Figure 1 , Figure 2a and Figure 2b The ±800kV UHV DC transmission system simulation model shown in the figure evaluates the discharge current of the EM arrester under the severe working condition of single-pole line short circuit, uses square wave pulse to approximate the discharge current, and determines the total amplitude of the long wave of the EM arrester discharge current and the square wave pulse width;

[0049] S2. Establishment Figure 3 The shock wave test platform shown in the figure selects the number of resistors according to the platform test capability, groups the selected resistors, and tries to increase the number of parallel columns of the arrester valve within the test capability. Calculate the number of parallel columns and the number of single-column resistors, perform current loop calibration, and apply preset square wave pulses to the arrester valve. The number of pulses borne by a single column is close to the number of simulations, with an error of no more than 20%.

[0050] S3. Collect test data, calculate the current unevenness coefficient and range based on the test data, and complete the shunt unevenness evaluation.

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

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

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

[0054] 3) DC filter. The DC filter is installed at the outlet of the converter station and connected 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 suppressing the harmonic current from entering the DC line.

[0055] 4) AC filter. The AC filter is set between the AC system and the converter transformer, connected in parallel with the AC system bus, and realizes low-resistance filtering characteristics for certain frequencies through impedance design. 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 and reduce the harmonic voltage and current of the DC line. It also has the function of reducing the probability of inverter commutation failure and limiting short-circuit current.

[0057] 6) DC overhead lines. DC overhead lines are transmission lines connecting rectifier stations and inverter stations.

[0058] 7) Modeling of multi-column parallel arrester circuit. To facilitate the simulation and analysis of non-uniformity, each column of the EM arrester is simulated as a separate component, and the core of the EM arrester model is composed of multi-column parallel nonlinear resistors.

[0059] In this simulation model, the severe working condition of single-pole short circuit is simulated to obtain the overvoltage, discharge current and energy absorption of the EM arrester under this working condition. The discharge current of the EM arrester under the severe working condition of single-pole short circuit is similar to a sine wave, such as Figure 4 As shown, for the convenience of the experiment, the square wave pulse is used for approximation. 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 the sine wave, and the amplitude is determined according to the area surrounded by the horizontal and vertical axes of the square wave and the area surrounded 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 multi-column parallel shock wave experimental test platform is established as follows: Figure 3 As shown, the test platform can be used to screen resistors.

[0061] The multi-column parallel test platform includes a transformer T, the primary winding of the transformer T is connected to a 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 spherical 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 spherical gap discharge device G is connected to the first end of the multi-column parallel resistor sheet, the second end of the multi-column parallel resistor sheet is grounded, and the multi-column parallel resistor sheet includes four parallel resistors R. Among them, the role 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. The capacitor C can play a filtering role.

[0062] When using a multi-column parallel shock wave test platform for resistor 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 spherical gap discharge, and the measurement result is the peak value of the impulse voltage.

[0063] When using a multi-column parallel shock wave experimental test platform to screen resistors, the multi-column resistors are connected in parallel to the shock wave test equipment, and 30 / 60us operating residual voltage tests and 8 / 20us lightning residual voltage tests are performed respectively. Resistors that have been broken down, perforated, or broken are eliminated, and the shunt current of each column resistor is measured and recorded to evaluate the shunt unevenness between columns.

[0064] The approximately square wave pulse determined in step S1 is used as the excitation wave for the test to test the volt-ampere characteristics of the resistor. The volt-ampere characteristics test steps of the resistor under long-wave excitation of the multi-column parallel lightning arrester are as follows:

[0065] S2.1. Resistor screening. The resistors are screened by DC parameter measurement, shock wave residual voltage test, resistor full current, resistive current, capacitive current, dielectric constant test, etc. The screened resistors are used for further non-uniformity coefficient analysis. Figure 5 The DC parameter measurement test platform shown is used for testing.

[0066] S2.2. Calibration of the measurement system of the shock wave test platform. Before the formal test, Figure 6The current loop is calibrated as shown to ensure that the current loop measurement results are consistent. The volt-ampere (VA) characteristic of a single resistor is measured, and four current loops are connected in series and connected to the four ports of the oscilloscope respectively. The test results are shown in Figure 7 As shown in the figure, it can be found that the results of the four current loops are consistent, which means that they meet the test standards and formal tests can be carried out.

[0067] S2.3, the resistors are grouped for formal testing. 20 resistors that have been basically screened are selected, and the resistors are grouped according to the 1mA DC reference voltage and the capacitance difference of 80% charge rate. Considering the experimental capacity, multi-column single pieces are selected, and the resistors are grouped into multi-column parallel combinations. Then, the 4 resistors in the same group are placed in the shock wave test platform. Figure 8 The schematic diagram of multiple resistors in parallel is shown in Figure 1. A preset square wave pulse is applied to obtain the test results, i.e., the current flowing through each resistor, the residual voltage, and the total current under the excitation of a 20ms approximate square wave pulse.

[0068] S2.4, data statistics and analysis. Record the current, residual voltage and total current flowing through each column resistor under 20ms approximate square wave pulse excitation. The volt-ampere characteristic curve of the arrester can be obtained based on the residual voltage and total current; according to the definition of the non-uniformity coefficient, calculate the non-uniformity coefficient of each set 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 and the calculated current non-uniformity coefficient and range, with a total of five sets of data.

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

[0071] Group No. Maximum current / kA Maximum absorbed energy / MJ Unevenness coefficient Very bad 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 unevenness coefficient and range are calculated respectively. According to GB / T 11032-2020 "AC gapless metal oxide arrester", the unevenness coefficient of the multi-column parallel arrester is calculated, which is defined as:

[0073]

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

[0075] The calculation method of range is:

[0076]

[0077] Where: γ is the non-uniformity coefficient; I max It is the maximum current peak value passing through the resistor column or lightning arrester element, in ampere (A); I min It is the minimum peak current passing through the resistor column or lightning arrester element, measured in ampere (A).

[0078] For EM arresters used in ±800kV DC systems, the current extreme difference index should be controlled to <0.3.

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

[0080] The term "consisting of" describing a combination shall include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to illustrate that any of the attributes described that "may" be included are optional.

[0081] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0082] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A method for testing the current shunting non-uniformity of valve plates of EM arresters in high-voltage DC lines, characterized in that: include: S1. Establish a high-voltage direct current transmission system simulation model, evaluate the discharge current of the EM arrester under the severe working condition of single-pole line short circuit based on the high-voltage direct current transmission system simulation model, use square wave pulse to approximate the discharge current, and determine the total amplitude and square wave pulse width of the long-wave discharge current of the EM arrester; S2, applying the square wave pulse to the resistor of the EM arrester under test, testing the current of each resistor and the total current of the arrester under the working condition; the total amplitude and pulse width of the square wave pulse are the same as the total amplitude and pulse width of the long wave of the EM arrester discharge current; S3. Calculate the current non-uniformity coefficient and the range of the resistor current based on the current of each resistor column and the total current.

2. The method for testing the non-uniformity of valve current diversion of EM arrester in high-voltage direct current line according to claim 1 is characterized in that: In the step S1, when establishing the high voltage direct current transmission system simulation model, each column resistor of the EM arrester is simulated as a separate component.

3. The method for testing the non-uniformity of valve current diversion of EM arrester in high voltage DC line according to claim 1 is characterized in that: The step S2 comprises the following steps: S2.

1. Screen the resistors through DC parameter measurement, shock wave residual voltage test, resistor full current, resistive current, capacitive current, and dielectric constant test; S2.

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

3. Select the resistors after screening and group them. Then put all the resistors in the same group into the shock wave test platform, apply square wave pulses, and record the current, residual voltage and total current of the arrester flowing through each column of resistor under the square wave pulse.

4. The method for testing the non-uniformity of valve current diversion of EM arrester in high-voltage direct current line according to claim 3 is characterized in that: In the step S2.3, the resistors are grouped according to the 1 mA DC reference voltage and the capacitance difference of 80% charge rate.

5. The method for testing the non-uniformity of valve current diversion of EM arrester in high-voltage direct current line according to claim 3 is characterized in that: In the step S2.3, after the residual voltage and the total current are obtained, the volt-ampere characteristic curve of the arrester is obtained according to the residual voltage and the total current of the arrester.

6. The method for testing the current shunting non-uniformity of valve plates of EM arresters of high-voltage direct current lines according to claim 1 is characterized in that: In step S3, the range is: the quotient of the difference between the maximum current and the minimum current in each column connected in parallel and the average current of each column.

7. The method for testing the current shunting non-uniformity of valve plates of EM arresters of high-voltage direct current lines according to claim 1 is characterized in that: The extreme difference of the resistor current is used as the evaluation standard for shunt non-uniformity.

8. A high-voltage DC line EM arrester valve plate current shunt non-uniformity test system, characterized in that: include: A simulation module, used for constructing a high-voltage direct current transmission system including an EM arrester valve plate, and obtaining preset square wave pulse parameters based on the high-voltage direct current transmission system; The shock wave test platform is used to test the current of each resistor column and the total current of the EM arrester under the working condition by applying a preset square wave pulse; The calculation module is used to calculate the current unevenness coefficient and the range according to the current of each resistor column and the total current of the lightning arrester.

9. The high-voltage DC line EM arrester valve plate current shunting non-uniformity testing system according to claim 8 is characterized in that: The shock wave test platform comprises a transformer T, wherein 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 spherical gap discharge device G, and the other end is used to connect a tested resistor.

10. The high-voltage DC line EM arrester valve plate current shunting non-uniformity testing system according to claim 8, characterized in that: The switch branch and the capacitor C are connected in parallel.

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