A method for parallel grouping of multi-column surge arresters

Abstract

This application relates to the field of multi-column surge arrester technology, and in particular to a method for parallel connection and grouping of multi-column surge arresters, comprising the following steps: S1, performing aging screening and energy withstand tests on zinc oxide resistors of the same batch; S2, measuring the DC reference voltage U of each resistor. ref 0.75U ref Leakage current I0 under lightning surge, residual voltage U under lightning surge L and the residual operating voltage U under the operating wave S S3, select resistors in three stages; S4, operate the residual voltage U S The primary basis for grouping is a combination of high and low voltage resistors, ensuring that the residual voltage deviation of each series-connected resistor group is less than a first preset value and the DC reference voltage deviation is less than a second preset value. This rigorous selection process guarantees the consistency of resistor performance, and the reasonable grouping method makes the electrical performance of each resistor group more balanced. This improves the operating waveform withstand capability and current sharing characteristics of the multi-column surge arrester, reducing the probability of MOV failure due to uneven current distribution.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of multi-column lightning arresters, in particular to a multi-column lightning arrester parallel matching method. BACKGROUND

[0002] In the development process of DC converter stations, the importance of high-voltage DC circuit breakers is increasingly prominent. As a core component of electrical protection, it plays a key role in ensuring the safe, economic and flexible operation of the DC system. When the system encounters a fault, the high-voltage DC circuit breaker can quickly cut off the circuit, effectively isolating the fault area and fault point, thereby ensuring the safe off-network of the line. It also plays an indispensable role in flexible DC networking and is one of the key devices for stable operation of related technologies. As an important component of high-voltage DC circuit breakers, metal oxide arresters (MOV) have characteristics such as high voltage level, large energy absorption, and long absorption time. Their electrical stress and application conditions are quite different from traditional application scenarios. With the continuous development of high-voltage DC transmission technology, the performance requirements for high-voltage DC circuit breakers and their components are becoming higher and higher, and the stable and reliable operation of metal oxide arresters has gradually become the focus of attention in high-voltage DC circuit breaker product design and engineering operation.

[0003] Currently, for multi-column parallel lightning arresters, the matching principles mainly include DC reference voltage test, residual voltage test, and current distribution screening test. In fact, most of these matching criteria are borrowed from the parameters of AC station lightning arresters. In terms of related standards, GB / T22389-2023 "High-voltage DC converter station without gap metal oxide arrester" does not mention the related information of DC circuit breaker MOV, and only GB / T38328-2019 "Common technical requirements for high-voltage DC circuit breakers of flexible DC systems" refers to the DC circuit breaker MOV as the energy absorption branch of the DC circuit breaker and mentions some related test requirements. In addition, scholars have proposed a variety of key technologies for improving the energy consumption branch MOV of high-voltage DC circuit breakers, such as the MOV energy absorption simulation technology proposed by Yang Bing et al., the MOV consistency and monitoring protection, and the key technology research suitable for high-voltage DC circuit breaker MOV test verification, but it is not specifically expanded; Liu Yaping et al. proposed the reliability improvement control of the energy consumption branch MOV of the flexible DC transmission project high-voltage DC circuit breaker, but did not specifically describe how to match the resistance sheets. The existing lightning arrester matching method has certain defects, and the multi-column parallel lightning arrester in actual operation is prone to problems such as insufficient operating wave resistance and poor current sharing characteristics due to the limitations of the existing matching criteria, which leads to MOV failure due to uneven current distribution and affects the stable and reliable operation of the high-voltage DC circuit breaker. SUMMARY

[0004] The application provides a parallel grouping method of multi-column lightning arresters, which can improve the operating wave resistance and current distribution characteristics of the multi-column lightning arresters.

[0005] The above object of the application is achieved by the following technical solutions.

[0006] The application provides a parallel grouping method of multi-column lightning arresters, which comprises the following steps.

[0007] S1, aging screening and energy resistance testing are performed on zinc oxide varistors in the same batch;

[0008] S2, the DC reference voltage U of the varistor is measured piece by piece; ref , the leakage current I0 under 0.75U ref , the impulse residual voltage U L under lightning wave and the operating residual voltage U S under operating wave are measured;

[0009] S3, the varistors are screened three times: the first screening is based on the leakage current I0, the second screening is based on the consistency of impulse current, and the third screening is based on the consistency of the operating wave voltage ratio K S and the lightning wave voltage ratio K L , wherein K S =U S / U ref , and K L =U L / U ref ;

[0010] S4, high-low matching grouping is performed by taking the operating residual voltage U S as the main grouping basis, so that the operating residual voltage deviation of the varistor group in series in each column is less than a first preset value, and the DC reference voltage value deviation is less than a second preset value. The strict screening process ensures the consistency of the varistor performance, and the reasonable grouping method makes the electrical performance of the varistor group in each column more balanced, so that the operating wave resistance and current distribution characteristics of the multi-column lightning arresters are improved, and the probability of MOV failure caused by uneven current distribution is reduced.

[0011] Further, step S5 of testing the current distribution under operating wave of the grouped parallel varistor column is included: if the maximum current distribution unevenness coefficient β is greater than a third preset value, step S4 is returned to further adjust the grouping. Through the test, whether the grouped lightning arrester reaches the expected current distribution effect can be verified, and if the current distribution unevenness coefficient is too large, the grouping can be further adjusted.

[0012] Further, step S1 comprises: performing an alternating current accelerated aging test, and applying multiple square wave impulses to eliminate the resistance chip which does not meet the aging test and energy tolerance. The high temperature and high charge rate environment here can simulate the more severe working conditions that the lightning arrester may encounter in actual operation, accelerate the aging process of the resistance chip, so as to screen out the resistance chip with stable performance. The square wave impulse can test the ability of the resistance chip to withstand energy in a short time. The resistance chip which does not meet the requirement may be damaged in actual use, affecting the performance of the lightning arrester.

[0013] Further, in step S3, the leakage current threshold of the initial screening is 20 μA, and the resistance chip with a leakage current I0 less than 20 μA and a similar value is selected as the initial screening result. If the leakage current is too large, it indicates that the insulation performance of the resistance chip is poor, which may cause current leakage and affect the normal operation of the lightning arrester. A high-precision ammeter can be used to measure the leakage current, and the resistance chip with a leakage current not meeting the requirement is eliminated.

[0014] Further, in step S3, the impulse current difference threshold of the secondary screening is 1%, and the resistance chip with an impulse current difference within 1% during the residual voltage test is selected as the secondary screening result. The consistency of the impulse current reflects the response characteristics of the resistance chip when it is subjected to an impact. The resistance chip with good consistency can better share the current and improve the current sharing characteristics when used in parallel.

[0015] Further, the first preset value and the second preset value are both 0.05%.

[0016] Further, the matching strategy of high-low alternation is adopted in the grouping operation in step S4: after arranging the operation residual voltage U S in descending order, the resistance chips are grouped according to the (Rmax, Rmin) pairing principle.

[0017] Further, the mathematical expression of the pairing principle is:

[0018] Let the sorting sequence S = [S1, S2,..., S n ] where U S1 ≥ U S2 ≥... ≥ U Sn ,

[0019] Then the kth column distribution sequence is (S k , S n-k+1 ), k = 1, 2,..., m, and m is the total number of columns. This grouping method can make the operation residual voltage of each column resistance chip group more balanced and reduce the deviation.

[0020] Further, the following formula is used to calculate the operation residual voltage deviation and the DC reference voltage value deviation:

[0021] δX = (X Max - XMin ) / [(X Max +X Min ) / 2]x100%, wherein X represents U S and U ref . Through this calculation method, the operating residual voltage deviation and DC reference voltage value deviation of each column series resistor group can be accurately evaluated.

[0022] Further, in S3, for the collaborative consistency screening of the operating wave voltage ratio Ks and the lightning wave voltage ratio KL, the following formula is used for evaluation: Z = a * K S + b * K L , wherein Z is a comprehensive index, a and b are weight coefficients and a + b = 1. By comparing the value of the comprehensive index Z, resistor groups with similar values can be screened, which can make the screening more accurate and further improve the consistency of the resistors.

[0023] In summary, the present application at least includes the following beneficial technical effects:

[0024] The multi-column surge arrester parallel grouping method provided by the embodiments of the present application mainly includes aging screening and energy tolerance test of resistors, measurement of multiple parameters of resistors, three times of resistor screening, and resistor grouping based on operating residual voltage. Through a series of screening and grouping steps, the operating residual voltage deviation and DC reference voltage value deviation of each column series resistor group are ensured to be within a small range. The aging screening and energy tolerance test exclude resistors with unstable performance, and the multiple screening steps (based on leakage current, impulse current consistency, operating wave voltage ratio K S and lightning wave voltage ratio K L three times of screening) further optimize the performance parameters of the resistors, and the reasonable grouping method (high-low matching grouping based on operating residual voltage) makes the electrical performance of each column resistor group more balanced, improves the operating wave resistance of the multi-column surge arrester and the current sharing characteristics, and reduces the risk of MOV failure caused by uneven current distribution. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a flowchart of the parallel grouping method of the column surge arrester of the embodiments of the present application. DETAILED DESCRIPTION

[0026] The following embodiments will help those skilled in the art to further understand the role of the present application, but do not limit the present application in any form. It should be pointed out that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0027] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, technologies, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, methods, circuits, and devices are omitted so as not to obscure the description of the present application with unnecessary detail.

[0028] It is to be understood that the terminology "including", when used in the present specification and in the following claims, does not exclude the presence of other features, integers, steps, operations, elements, and / or groups thereof.

[0029] The parallel grouping method of the multi-column arrester provided by the embodiments of the present application mainly adopts multi-step screening and grouping of zinc oxide varistors, so as to improve the operating wave resistance and current sharing characteristics of the multi-column arrester. The following will be described in combination with the accompanying drawings. Figure 1 The present application will be described in further detail. Embodiments

[0030] The parallel grouping method of the multi-column arrester provided by the embodiments of the present application includes the following steps:

[0031] S1, aging screening and energy resistance test are performed on zinc oxide varistors of the same batch;

[0032] S2, the DC reference voltage U ref , the leakage current I0under 0.75U ref , the impulse residual voltage U L under 8 / 20 μs lightning wave, and the operating residual voltage U S under 30 / 60 μs operating wave of the varistors are measured piece by piece. ref The basic electrical properties of the varistors can be understood, the leakage current I0can reflect the insulation performance of the varistors, and the impulse residual voltage U L and the operating residual voltage U S are related to the protection performance of the arrester under different working conditions. Professional electrical measuring instruments such as voltmeter and ammeter can be used during measurement, and corresponding measurement standards and methods are used.

[0033] S3, the varistors are screened three times: the first screening is based on the leakage current I0, the second screening is based on the consistency of the impulse current, and the third screening is based on the consistency of the operating wave voltage ratio K S and the lightning wave voltage ratio K L , wherein K S = U S / U ref , and K L=U L / U ref ;

[0034] S4, with the operating residual voltage U S The high and low matching groups are matched as the main matching basis, so that the operating residual voltage deviation of each column series resistance disc group is less than a first preset value, and the DC reference voltage value deviation is less than a second preset value. In practice, the first preset value and the second preset value are generally both set to 0.05%. The smaller the operating residual voltage deviation of each column resistance disc group is, the more balanced the electrical performance of each column resistance disc group is, and the better the operating wave resistance of the multi-column lightning arrester and the current sharing characteristic are.

[0035] Specifically, step S1 includes: performing an alternating current accelerated aging test at 115℃ and 95% charge rate, applying multiple square wave impulses (such as applying 4 times 2ms square wave impulses), and removing resistance discs that do not meet the aging test and energy resistance. For example, a professional aging test box is used, the same batch of zinc oxide resistance discs are placed in the box, and the temperature and charge rate parameters are set for testing. The high temperature and high charge rate environment here can simulate the relatively harsh working conditions that the lightning arrester may encounter in actual operation, accelerate the aging process of the resistance disc, and screen out resistance discs with stable performance. Square wave impulse can test the ability of resistance disc to withstand energy in a short time. Resistance discs that do not meet the requirements may be damaged in actual use, affecting the performance of the lightning arrester. A square wave generator can be used to generate square wave impulses for multiple impact tests on the resistance disc.

[0036] Specifically, in step S3, the leakage current threshold of the initial screening is 20μA, and the resistance discs with leakage current I0 less than 20μA and similar values are selected as the initial screening. If the leakage current is too large, it indicates that the insulation performance of the resistance disc is poor, which may cause current leakage and affect the normal operation of the lightning arrester. A high-precision ammeter can be used to measure the leakage current, and the resistance discs with leakage current not meeting the requirements are removed. The difference threshold of the impulse current for the secondary screening is 1%, and the resistance discs with impulse current difference within 1% during residual voltage test are selected as the secondary screening; the consistency of the impulse current reflects the response characteristics of the resistance disc when it is impacted. Resistance discs with good consistency can better share current when used in parallel, improving the current sharing characteristic. During the residual voltage test, a current sensor or other equipment can be used to measure the impulse current and compare and screen. The third screening is based on the cooperative consistency of the operating wave pressure ratio K S =U S / U ref and the lightning wave pressure ratio K L =U L / U ref , and resistance discs with consistent operating pressure ratio K S and lightning pressure ratio K L are selected. The operating wave pressure ratio K S and the lightning wave pressure ratio KL The performance of the resistance disc under different waveforms can be comprehensively reflected, and the resistance disc with good consistency can make the lightning arrester have good protection effect under various working conditions. The operating wave voltage ratio and the lightning wave voltage ratio of each resistance disc can be calculated and compared for screening. Embodiments

[0037] The parallel grouping method of the multi-column lightning arrester provided by the embodiments of the application comprises the following steps:

[0038] S1, aging screening and energy tolerance test are performed on zinc oxide resistance discs in the same batch;

[0039] S2, the DC reference voltage U ref , the leakage current I ref under 0.75U L , the impulse residual voltage U L under 8 / 20 μs lightning wave, and the operating residual voltage U S under 30 / 60 μs operating wave of the resistance disc are measured piece by piece.

[0040] S3, the resistance disc is screened three times: the first screening is based on the leakage current I S , the second screening is based on the consistency of the impulse current, and the third screening is based on the consistency of the operating wave voltage ratio K L and the lightning wave voltage ratio K S , wherein K S = U ref / U L , and K L = U ref / U S ;

[0041] S4, high-low matching grouping is performed by taking the operating residual voltage U S as the main grouping basis, so that the operating residual voltage deviation of the series resistance disc group of each column is less than 0.05%, and the DC reference voltage value deviation is less than 0.05%.

[0042] S5, current distribution test under operating wave is performed on the parallel resistance disc column after grouping, if the maximum current distribution uneven coefficient β is greater than 5%, return to step S4 for further adjustment until the maximum current distribution uneven coefficient β is less than 5%, so as to ensure that the current distribution characteristics of the multi-column lightning arrester are good. The industry general standard only requires that β≤10%, and the maximum current distribution uneven coefficient β can be controlled to be less than 5% in the embodiment, so that the current distribution precision is improved by more than 2 times compared with the conventional method.

[0043] Specifically, the grouping operation in step S4 adopts a high-low alternating matching strategy: after arranging the operating residual voltage U S values in descending order, grouping is performed according to the (Rmax, Rmin) pairing principle. The mathematical expression of the pairing principle is:

[0044] Let the sorting sequence S = [S1, S2,..., S n ] where U S1 ≥ U S2 ≥... ≥ U Sn ,

[0045] The kth column distribution sequence is (S k , S n-k+1 ), k = 1, 2,..., m, m is the total number of columns. This grouping method can make the operating residual voltage of each column resistor group more balanced and reduce the deviation. To illustrate in detail, assume that there are a total of 10 resistors, and the corresponding sequence of the operating residual voltage in descending order is S = [S1, S2, S3, S4, S5, S6, S7, S8, S9, S 10 ], where U S1 ≥ U S2 ≥... ≥ U S10 , the total number of columns m = 5. Then according to the above pairing principle, the first column distribution sequence is (S1, S 10 ), the second column distribution sequence is (S2, S9), the third column distribution sequence is (S3, S8), the fourth column distribution sequence is (S4, S7), and the fifth column distribution sequence is (S5, S6). Such a pairing method combines the largest and smallest operating residual voltage resistors together, making the operating residual voltage of each column as balanced as possible. Embodiment

[0046] The multi-column surge arrester parallel grouping method provided by the embodiment of the application comprises the following steps:

[0047] S1, aging screening and energy tolerance test are performed on zinc oxide resistors in the same batch;

[0048] S2, the DC reference voltage U ref , the leakage current I0 under 0.75U ref , the impulse residual voltage U L under 8 / 20 μs lightning wave, and the operating residual voltage U S under 30 / 60 μs operating wave are measured on the resistors piece by piece;

[0049] S3, the resistors are screened three times: first screening based on the leakage current I0, second screening based on the consistency of the impulse current, and third screening based on the consistency of the operating wave voltage ratio K S and the lightning wave voltage ratio K L , where K S = U S / U ref , and K L = U L / U ref ;

[0050] S4, to operate the residual voltage U S As the main composition, the high and low composition is matched to make the operating residual voltage deviation of each column series resistance chip group less than 0.05%, and the DC reference voltage value deviation less than 0.05%;

[0051] S5, the current distribution test under the operating wave is performed on the matched parallel resistance chip column, if the maximum current distribution uneven coefficient β is greater than 5%, return to step S4 for further adjustment.

[0052] Specifically, the deviation calculation uses δ X =(X Max - X Min ) / [(X Max + X Min ) / 2]×100%, wherein X represents one of the operating residual voltage U S and the DC reference voltage U ref . For example, for the operating residual voltage data of a group of resistance chips, the maximum value U SMax =100V, and the minimum value U SMin =98V, the operating residual voltage deviation δ US =(100-98) / [(100+98) / 2]×100%≈2.02% is calculated by the formula; for the DC reference voltage, if the maximum value U refMax =200V, and the minimum value U refMin =198V, the DC reference voltage deviation δ Uref =(200-198) / [(200+198) / 2]×100%≈1.01% is calculated by the formula. Through this calculation method, the operating residual voltage deviation and the DC reference voltage value deviation of each column series resistance chip group can be accurately evaluated. The current distribution test under the operating wave is performed on a plurality of parallel resistance chip columns matched according to the above matching method, so that the maximum current distribution uneven coefficient β is less than 5%. Embodiment

[0053] The multi-column lightning arrester parallel matching method provided by the embodiment of the application comprises the following steps:

[0054] S1, aging screening and energy tolerance test are performed on the zinc oxide resistance chips of the same batch;

[0055] S2, the DC reference voltage U ref , the leakage current I0 under 0.75U ref , the impulse residual voltage U L under 8 / 20 μs lightning wave, and the operating residual voltage U S under 30 / 60 μs operating wave of the resistance chips are measured piece by piece;

[0056] S3, three times of screening of the resistance pieces: first screening based on the leakage current I0, second screening based on the consistency of the impulse current, and third screening based on the consistency of the operating wave voltage ratio K S and the lightning wave voltage ratio K L , wherein K S =U S / U ref , K L =U L / U ref ;

[0057] S4, high and low matching is performed with the operating residual voltage U S as the main matching basis, so that the operating residual voltage deviation of each column of series resistance piece groups is less than 0.05%, and the DC reference voltage value deviation is less than 0.05%;

[0058] S5, current distribution test under the operating wave is performed on the matched parallel resistance piece column, and if the maximum current distribution uneven coefficient β is greater than 5%, the step S4 is returned for further adjustment of the matching.

[0059] The volt-ampere characteristic curve of the resistance piece is recorded synchronously during the matching process to assist in judging the consistency. The volt-ampere characteristic curve can intuitively reflect the electrical performance of the resistance piece, and the consistency of the resistance piece can be more accurately judged by comparing the volt-ampere characteristic curves of different resistance pieces, thereby further improving the accuracy of the matching. Embodiment

[0060] The multi-column lightning arrester parallel matching method provided by the embodiment of the application comprises the following steps:

[0061] S1, aging screening and energy tolerance test are performed on the zinc oxide resistance pieces of the same batch;

[0062] S2, the DC reference voltage U ref , the leakage current I0 under 0.75U ref , the impulse residual voltage U L under the 8 / 20 μs lightning wave, and the operating residual voltage U S under the 30 / 60 μs operating wave of the resistance pieces are measured piece by piece;

[0063] S3, three times of screening of the resistance pieces: first screening based on the leakage current I0, second screening based on the consistency of the impulse current, and third screening based on the consistency of the operating wave voltage ratio K S and the lightning wave voltage ratio K L , wherein K S =U S / U ref , K L =U L / U ref ;

[0064] S4, with the operating residual voltage US as the main matching basis, high and low matching is performed to make the operating residual voltage deviation of each column of series-connected resistor chip sets less than 0.05%, and the DC reference voltage value deviation less than 0.05%;

[0065] S5, the current distribution test under the operating wave is performed on the matched parallel resistor chip column, and if the maximum current distribution unevenness coefficient β is greater than 5%, return to step S4 for further adjustment of the matching.

[0066] Specifically, in the step S3 of screening resistor chips three times, for the operating wave voltage ratio K S =U S / U ref and the lightning wave voltage ratio K L =U L / U ref , a better algorithm can be used for evaluation. Introducing weight coefficients α and β (α + β = 1), according to different application scenarios of different emphasis on operating wave and lightning wave, different weights are given to K S and K L , and then the comprehensive index Z is calculated to screen resistor chips, and the specific formula is: Z = α * K S + β * K L .

[0067] For example, in a certain application scenario, more emphasis is placed on the performance of the operating wave, and α = 0.7 and β = 0.3. Assuming that there are 4 resistor chips, their parameters are as follows:

[0068] Resistor chip 1: U S1 = 110V, U ref1 = 100V, U L1 = 120V, then K S1 = U S1 / U ref1 = 1.1, K L1 = U L1 / U ref1 = 1.2, Z1 = 0.7 * 1.1 + 0.3 * 1.2 = 1.13;

[0069] Resistor chip 2: U S2 = 108V, U ref2 = 100V, U L2 = 118V, then K S2 = U S2 / U ref2 = 1.08, K L2 = U L2 / Uref2 = 1.18, Z2 = 0.7 * 1.08 + 0.3 * 1.18 = 1.11;

[0070] Resistor sheet 3: U S3 = 106V, U ref3 = 100V, U L3 = 116V, then K S3 = U S3 / U ref3 = 1.06, K L3 = U L3 / U ref3 = 1.16, Z3 = 0.7 * 1.06 + 0.3 * 1.16 = 1.09;

[0071] Resistor sheet 4: U S3 = 107V, U ref3 = 100V, U L3 = 117V, then K S3 = U S3 / U ref3 = 1.07, K L3 = U L3 / U ref3 = 1.17, Z3 = 0.7 * 1.06 + 0.3 * 1.16 = 1.1.

[0072] Two resistor sheets with the best consistency are selected from the above four resistor sheets, i.e., resistor sheet 2 and resistor sheet 4, and the Z values thereof are closest. By comparing the values of the comprehensive index Z, resistor sheets with similar values can be screened and grouped, and such a method can make the screening more accurate and further improve the consistency of the resistor sheets.

[0073] By comprehensively and strictly screening and grouping the zinc oxide resistor sheets in the same batch, the performance consistency of the resistor sheets is ensured from multiple aspects, and the operating wave resistance and current distribution characteristics of the multi-column lightning arrester are significantly improved. Specifically, the aging screening and energy resistance test exclude the resistor sheets with unstable performance, the multiple screening steps further optimize the performance parameters of the resistor sheets, the reasonable grouping method makes the electrical performance of each column resistor group more balanced, and finally the risk of MOV failure caused by uneven current distribution is reduced, and the stable and reliable operation ability of the high-voltage direct-current circuit breaker is improved.

[0074] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method for parallel connection and grouping of multi-column surge arresters, characterized in that, Includes the following steps: S1, aging screening and energy tolerance test of the same batch of zinc oxide resistors; S2, Measure the DC reference voltage U of each resistor element. ref 0.75U ref Leakage current I0 under lightning surge, residual voltage U under lightning surge L and the residual operating voltage U under the operating wave S ; S3, resistor elements are screened in three stages: initial screening based on leakage current I0, secondary screening based on inrush current consistency, and secondary screening based on operating surge voltage ratio K. S With lightning surge voltage ratio K L The consistency of the collaboration is filtered three times, where K S =U S / U ref K L =U L / U ref ; S4, to operate residual pressure U S High and low voltage combinations are used as the main basis for matching, so that the operating residual voltage deviation of each series resistor group is less than the first preset value and the DC reference voltage value deviation is less than the second preset value. The initial screening based on leakage current I0 involves selecting resistors whose leakage current I0 is less than or similar to the leakage current threshold as the initial screening result. The leakage current threshold is 20μA. The secondary screening based on the consistency of the impact current involves selecting resistors whose impact current difference during the residual voltage test is less than the impact current difference threshold as the secondary screening result. The impact current difference threshold is 1%. The basis of the operating wave pressure ratio K S With lightning surge voltage ratio K L The coordination consistency is screened three times based on the operational wave pressure ratio K. S With lightning surge voltage ratio K L The formula Z=α*K is used. S +β*K L A screening process was conducted, selecting resistors with similar Z values ​​as the results of three rounds of screening. Z represents a comprehensive index, α and β are weighting coefficients with α + β = 1, and K... S =U S / U ref K L =U L / U ref ; The high-low pairing adopts a high-low alternating matching strategy, which is to adjust the operating residual voltage U. S After sorting the values ​​in descending order, they are grouped according to the pairing principle of (Rmax, Rmin), where the mathematical expression of the pairing principle is: Let the sorted sequence be S = [S1, S2, ..., S...]. n Among them, U S1 ≥U S2 ≥...≥U Sn Then the allocation sequence of the k-th column is (S k ,S n-k+1 k = 1, 2, ..., m, where m is the total number of columns; Where Rmax is the residual operating voltage U in the resistor array to be matched. S The resistor with the highest value, R min The residual operating voltage U in the resistors to be matched S The resistor with the lowest value, S1 is the first resistor in sequence S, U S1 It is the residual operating voltage U of resistor S1 S Value, S n It is the nth resistor in sequence S, U Sn It is resistor S n Operating residual pressure U S value.

2. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, Including step S5: Perform current distribution test on the parallel resistor columns after grouping under the operating wave. If the maximum current distribution non-uniformity coefficient β is greater than the third preset value, return to step S4 to further adjust the grouping.

3. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, Step S1 includes: conducting an AC accelerated aging test and applying multiple square wave shocks to remove resistors that do not meet the aging test and energy tolerance requirements.

4. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, Both the first preset value and the second preset value are 0.05%.

5. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, The following formulas are used to calculate both the operating residual voltage deviation and the DC reference voltage numerical deviation: δ X =(X Max -X Min ) / [(X Max +X Min ) / 2]×100%, Where X represents U S or U ref One of the two, X Max X represents the maximum value of parameter X corresponding to each resistor element within each column. Min This represents the minimum value of parameter X corresponding to each resistor element within each column.

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