Parallel matching method for multi-column lightning arresters

Abstract

The invention relates to the technical field of multi-column lightning arresters, in particular to a multi-column lightning arrester parallel matching method, which comprises the following steps of S1, performing aging screening and energy tolerance testing on zinc oxide resistor discs of the same batch; s2, measuring the direct-current reference voltage Uref of the resistor discs, the leakage current I0 under 0.75 Uref, the impact residual voltage UL under the lightning wave and the operation residual voltage US under the operation wave one by one; s3, screening the resistor discs for three times; and S4, high-low matching is carried out by taking the operation residual voltage US as a main matching basis, so that the operation residual voltage deviation of each column of series resistor disc group is smaller than a first preset value, and the direct current reference voltage numerical value deviation is smaller than a second preset value. The strict screening process ensures the consistency of the performance of the resistor discs, and the reasonable grouping mode makes the electrical performance of each column resistor disc group more balanced, thereby achieving the effect of improving the operating wave endurance capability and the current sharing characteristic of the multi-column lightning arrester, and reducing the probability of faults caused by uneven current distribution of the MOV.

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. The application provides a parallel grouping method of multi-column lightning arresters, which comprises the following steps. S1, aging screening and energy resistance testing are performed on zinc oxide varistors in the same batch; S2, the DC reference voltage U of the varistor is measured piece by piece; ref , the leakage current I0 under 0.75U, the impulse residual voltage U under lightning wave and the operating residual voltage U under operating wave are measured; ref L S ; 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 ; 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 of the multi-column lightning arrester and the current distribution characteristics are improved, and the probability of MOV failure caused by uneven current distribution is reduced.

[0006] Further, step S5 of testing the current distribution under the operating wave of the grouped parallel varistor column is further included: if the maximum current distribution uneven 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 uneven coefficient is too large, the grouping can be further adjusted.

[0007] ​​Further, step S1 comprises: performing alternating current accelerated aging test, and applying multiple square wave impulses to eliminate the resistance disc 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 disc, so as to screen out the resistance disc with stable performance. The square wave impulse can test the ability of the resistance disc to withstand energy in a short time. The resistance disc which does not meet the requirement may be damaged in actual use, affecting the performance of the lightning arrester.

[0008] Further, in step S3, the leakage current threshold of the initial screening is 20 μA, and the resistance disc 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 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 disc with a leakage current not meeting the requirement is eliminated.

[0009] Further, in step S3, the impulse current difference threshold of the secondary screening is 1%, and the resistance disc with an impulse current difference within 1% in the residual voltage test is selected as the secondary screening result. The consistency of the impulse current reflects the response characteristics of the resistance disc when it is subjected to an impact. The resistance disc with good consistency can better share the current and improve the current sharing characteristics when used in parallel.

[0010] Further, the first preset value and the second preset value are both 0.05%.

[0011] 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 discs are grouped according to the (Rmax, Rmin) pairing principle.

[0012] Further, the mathematical expression of the pairing principle is: Let the sorting sequence S=[S1, S2,..., S n ] where U S1 ≥U S2 ≥...≥U Sn , 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 disc group more balanced and reduce the deviation.

[0013] Further, the following formula is used to calculate the operation residual voltage deviation and the DC reference voltage value deviation: δX=(X Max -X Min ) / [(X Max +XMin ) / 2]x100%, wherein X represents U S and U ref One of the two. 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.

[0014] 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 the 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.

[0015] In summary, the present application at least includes the following beneficial technical effects: The multi-column surge arrester parallel grouping method provided by the embodiment 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 grouping of resistors according to 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. Among them, 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 according to 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

[0016] Figure 1 is a flowchart of the parallel grouping method of the column surge arrester of the embodiment of the present application. DETAILED DESCRIPTION

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The multi-column lightning arrester parallel grouping method 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 lightning arrester. The following will be described in combination with the accompanying drawings. Figure 1 The present application is described in further detail. Embodiments

[0021] The multi-column lightning arrester parallel grouping method provided by the embodiments of the present application includes the following steps: S1, aging screening and energy resistance test are performed on zinc oxide varistors of the same batch; 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 lightning 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.

[0022] 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 / Uref ; S4, with the operating residual voltage U S As the main matching basis, high and low matching is carried out, so that the operating residual voltage deviation of each column series resistance disc set 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 set to 0.05%. The smaller the operating residual voltage deviation of each column resistance disc set is, the more balanced the electrical performance of each column resistance disc set is, and the better the operating wave resistance of the multi-column lightning arrester and the current sharing characteristic are.

[0023] 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.

[0024] 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 K LThe 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 and screened. Embodiments

[0025] The parallel grouping method of the multi-column lightning arrester provided by the embodiments of the application comprises the following steps: S1, aging screening and energy resistance test are performed on the zinc oxide resistance discs in the same batch; 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 disc are measured piece by piece; S3, the resistance disc is 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 ; 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%; S5, the current distribution test under the operating wave is performed on the parallel resistance disc column after grouping, if the maximum current distribution uneven coefficient β is greater than 5%, the step S4 is returned to further adjust the grouping 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% by the embodiment, so that the current distribution precision is improved by more than 2 times compared with the conventional method.

[0026] 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: Let the sorting sequence S=[S1, S2,..., S n ] wherein U S1 ≥U S2 ≥...≥U Sn , then the kth column distribution sequence is (S k , S n-k+1 ), k = 1, 2, …, m, m is the total number of columns. This arrangement 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 ], wherein 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 pairing method combines the largest and smallest operating residual voltage resistors together, so that the operating residual voltage of each column is balanced as much as possible. Embodiment

[0027] The multi-column lightning arrester parallel grouping method provided by the embodiment of the application comprises the following steps: S1, aging screening and energy tolerance test are performed on zinc oxide resistors of the same batch; 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 resistors are measured piece by piece; S3, the resistors 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 ; S4, high-low pairing grouping is performed based on the operating residual voltage U S as the main grouping basis, so that the operating residual voltage deviation of each column resistor group is less than 0.05%, and the DC reference voltage value deviation is less than 0.05%; S5, current distribution test under the operating wave is performed on the parallel resistor column after grouping, and if the maximum current distribution uneven coefficient β is greater than 5%, the grouping is returned to step S4 for further adjustment.

[0028] Specifically, the deviation calculation adopts δ X =(X Max - X Min ) / [(X Max + X Min ) / 2]×100%, wherein X represents the operating residual voltage U S and one of the DC reference voltage U ref . For example, for the operating residual voltage data of a certain 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% can be 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% can be calculated by the formula. Through this calculation method, the operating residual voltage deviation and the DC reference voltage numerical deviation of each column of series resistance chip groups can be accurately evaluated. The current distribution test under the operating wave of a plurality of parallel resistance chip columns arranged according to the above grouping method can ensure that the maximum current distribution uneven coefficient β is less than 5%. Embodiment

[0029] The multi-column lightning arrester parallel grouping method provided by the embodiment of the application comprises the following steps: S1, aging screening and energy tolerance testing are performed on zinc oxide resistance chips of the same batch; S2, the DC reference voltage U ref , the leakage current I0 under 0.75U ref , the impulse residual voltage U L under 8 / 20μs lightning wave, and the operating residual voltage U S under 30 / 60μs operating wave of the resistance chips are measured piece by piece; S3, the resistance chips 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 , wherein K S =U S / U ref , and K L =U L / U ref ; S4, the resistance chips are grouped according to the operating residual voltage US As the main matching basis, high-low matching is carried out, so that the operating residual voltage deviation of each column of series resistance chip groups is less than 0.05%, and the DC reference voltage value deviation is less than 0.05%; S5, the current distribution test under the operating wave is carried out 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 of matching.

[0030] During the matching process, the volt-ampere characteristic curve of the resistance chip is recorded synchronously to assist in judging consistency. The volt-ampere characteristic curve can directly reflect the electrical performance of the resistance chip. By comparing the volt-ampere characteristic curves of different resistance chips, the consistency of the resistance chip can be more accurately judged, and the accuracy of the matching is further improved. Embodiment

[0031] The multi-column lightning arrester parallel matching method provided by the embodiment of the application comprises the following steps: S1, aging screening and energy resistance test are carried out on the zinc oxide resistance chips of the same batch; 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 chip are measured piece by piece; S3, the resistance chip is screened three times: the first screening is based on the leakage current I0, the second screening is based on the impulse current consistency, and the third screening is based on the cooperative 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 ; S4, high-low matching is carried out as the main matching basis, so that the operating residual voltage deviation of each column of series resistance chip groups is less than 0.05%, and the DC reference voltage value deviation is less than 0.05%; S5, the current distribution test under the operating wave is carried out 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 of matching.

[0032] Specifically, in the step S3 of screening the resistance chip three times, for the operating wave voltage ratio K S =U S / U ref and the lightning wave voltage ratio K L =U L / Uref The synergistic consistency screening can be evaluated by a better algorithm. Introducing weight coefficients a and β (a + β = 1), according to the different application scenarios of the operating wave and the lightning wave, giving K S and K L different weights, and then calculating the comprehensive index Z to screen the resistance sheet, the specific formula is: Z = a * K S + β * K L .

[0033] For example, in a certain application scenario, more emphasis is placed on the performance of the operating wave, a = 0.7, β = 0.3. Assuming there are 4 resistance sheets, their parameters are as follows: Resistance sheet 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; Resistance sheet 2: U S2 = 108V, U ref2 = 100V, U L2 = 118V, then K S2 = U S2 / U ref2 = 1.08, K L2 =U L2 / U ref2 = 1.18, Z2 = 0.7 * 1.08 + 0.3 * 1.18 = 1.11; Resistance 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; Resistance sheet 4: U S3 = 107V, Uref3 = 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.

[0034] From the above four resistance chips, the two with the best consistency are selected, i.e., resistance chip 2 and resistance chip 4, whose Z values are closest. By comparing the values of the comprehensive index Z, resistance chips with similar values can be selected for grouping, which can make the selection more accurate and further improve the consistency of the resistance chips.

[0035] By comprehensively and strictly screening and grouping the zinc oxide resistance chips of the same batch, the performance consistency of the resistance chips is ensured from multiple aspects, so that the operating wave resistance and current sharing characteristics of the multi-column lightning arrester are significantly improved. Specifically, the aging screening and energy resistance test exclude resistance chips with unstable performance, multiple screening steps further optimize the performance parameters of the resistance chips, and a reasonable grouping method makes the electrical performance of each column resistance chip group more balanced, ultimately reducing the risk of MOV failure caused by uneven current distribution and improving the stable and reliable operation ability of the high-voltage direct-current circuit breaker.

[0036] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; 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 selection is conducted in three stages: initial selection based on leakage current I0, secondary selection based on inrush current consistency, and secondary selection 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 / Uref,K L =U L / Uref; S4, to operate residual pressure U S The high and low voltages are matched 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 deviation is less than the second preset 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, In step S3, the leakage current threshold for the initial screening is 20μA, and resistors with leakage current I0 < 20μA and similar values ​​are selected as the initial screening results.

5. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, In step S3, the threshold for the difference in impact current during the secondary screening is 1%, and the resistors with an impact current difference of less than 1% during the residual voltage test are selected as the results of the secondary screening.

6. 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%.

7. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, The grouping operation in step S4 adopts a high-low alternating matching strategy: the operation residual voltage U S After sorting the values ​​in descending order, group them according to the (Rmax, Rmin) pairing principle.

8. The method for parallel connection and grouping of multi-post surge arresters according to claim 7, characterized in that, The mathematical expression for 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.

9. 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 and U ref One of the two.

10. The method for parallel connection and grouping of multi-post surge arresters according to claim 1, characterized in that, In S3, for the operating wave pressure ratio K S With lightning surge voltage ratio K L The consensus screening is evaluated using the following formula: Z = α * K S +β* K L Z is a comprehensive index, and α and β are both weighting coefficients with α + β = 1.

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