+ / -800kV converter station lightning arrester insulation cooperation checking method considering multiple lightning strokes

Abstract

The invention discloses a + / -800kV converter station lightning arrester insulation cooperation checking method considering multiple lightning strokes, and the method comprises the steps: S1, building a high-frequency electromagnetic transient simulation model according to the engineering practice and the high-frequency demands of lightning overvoltage simulation calculation; s2, multiple lightning stroke lightning current waveform parameters and lightning stroke time intervals are selected, and parameters capable of representing different frequencies of ground-to-ground lightning in the region where the research object is located are obtained; s3, simulating and analyzing residual voltage, current and absorbed energy of the lightning arrester at different positions of multiple lightning / multiple lightning shielding failure; s4, comparing and analyzing amplitude values of residual voltage, current and absorbed energy of the lightning arrester under single lightning stroke / multiple lightning stroke, and selecting a maximum value; and S5, proposing a lightning arrester configuration scheme, adjusting the type of the lightning arrester in the simulation model, and repeating the steps S3 and S4 to carry out secondary checking and adjustment. According to the method, a lightning arrester type selection scheme capable of effectively inhibiting single lightning overvoltage and multiple lightning overvoltage is provided, and the lightning accident rate of the lightning arresters in the converter station is reduced.

Description

Technical Field

[0001] The invention relates to the field of overvoltage protection and insulation coordination of a direct current system, and in particular to an insulation coordination verification method for a ±800kV converter station arrester taking multiple lightning strikes into consideration. Background Art

[0002] At present, the insulation coordination design of the arrester in the converter station in the ±800kV UHV DC transmission project is mainly based on the method in GB / T 28541-2012 "Insulation coordination of ±800kV high-voltage DC converter station equipment", that is, the system overvoltage level is obtained according to various severe conditions of internal overvoltage and external overvoltage of the system, and the arrester is selected after fully considering various margins. Then, the applicability of the arrester selection is verified by simulating the electrical stress amplitude of the arrester under various fault conditions, and finally the insulation coordination design scheme of the arrester in the converter station is obtained. Among them, in the verification calculation of the external overvoltage, that is, the lightning overvoltage, the 2.6 / 50μs specified in GB / T50064-2014 is usually used as the lightning current waveform in the project, and the applicability of the arrester selection is verified by the calculation results of a single lightning strike.

[0003] In the existing insulation coordination design method of converter station arresters, for the consideration of external overvoltage conditions, only the overvoltage that occurs in the system during a single lightning strike is considered, and the residual voltage, current and absorbed energy of the arrester under a single lightning strike are verified, but the electrical stress characteristics of the arrester under multiple lightning strikes are not fully considered (the electrical stress characteristics include the residual voltage, current, and absorbed energy of the arrester). As a result, the AC side arrester of the converter station in the existing project fails after being subjected to multiple lightning strikes with current amplitudes that do not reach the lightning withstand level, causing the burning of system-related equipment and system oscillation. It can be seen that the design of the insulation coordination of the converter station arrester considering only a single lightning strike can no longer meet the refined needs of the actual fault conditions, and it is urgent to improve the insulation coordination design method of the converter station arrester in combination with the characteristics of actual multiple lightning strikes. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide a method for checking insulation coordination of a ±800kV converter station arrester taking into account multiple lightning strikes.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for checking insulation coordination of arresters in ±800kV converter stations considering multiple lightning strikes, comprising:

[0007] S1. According to the high-frequency requirements of actual engineering and lightning overvoltage simulation calculation, a high-frequency electromagnetic transient simulation model for calculating lightning overvoltage under different operating modes is built;

[0008] S2. Study and analyze the lightning current parameters of multiple lightning strikes, select the lightning current waveform parameters and lightning strike time intervals of multiple lightning strikes, and obtain the parameters that can characterize the different frequencies of ground lightning in the area where the research object is located;

[0009] S3, simulation analysis of the residual voltage, current and absorbed energy of the arrester when multiple lightning strikes / multiple lightning strikes at different positions;

[0010] S4. Compare and analyze the amplitudes of the residual voltage, current and absorbed energy of the arrester under single lightning strike / multiple lightning strikes, and select the maximum value;

[0011] S5. Propose a lightning arrester configuration scheme with sufficient margin and meeting the overvoltage suppression requirements, adjust the lightning arrester type in the simulation model, and repeat S3 and S4 for secondary verification and adjustment.

[0012] Further, in said S1, according to the actual project and the high-frequency requirements of lightning overvoltage simulation calculation, a high-frequency electromagnetic transient simulation model for calculating lightning overvoltage under different operation modes is built, specifically:

[0013] S11 Based on the actual engineering topology and parameters, the high-frequency model simulation method of each key equipment in the converter station is analyzed;

[0014] S12 combines the actual topology of the line and tower to build a high-frequency electromagnetic transient simulation model of 7 towers and lines on the AC / DC side of the converter station.

[0015] Further, the S2, studies and analyzes the lightning current parameters of actual multiple lightning strikes, and selects typical multiple lightning strike lightning current waveform parameters and lightning strike time intervals, specifically:

[0016] The lightning current parameters of multiple return-to-ground lightning obtained by artificial lightning induction are analyzed. The lightning current parameters include the frequency of multiple return-to-ground lightning, the polarity of multiple return-to-ground lightning, the lightning current amplitude, the lightning current wave front time / wave tail time and the lightning strike time interval. The parameters that can characterize the ground lightning of different frequencies in the area where the research object is located are selected to provide conditions for subsequent simulation calculations.

[0017] Further, the S3, simulation analysis of the residual voltage, current and absorbed energy of the arrester when multiple lightning strikes / multiple lightning strikes at different positions, is specifically:

[0018] Calculate the maximum shielding failure current of different towers through electrical geometry model and calculate the lightning withstand level of different towers through simulation to determine the lightning current amplitude used for shielding failure calculation;

[0019] The multiple return-to-ground lightning parameters obtained from the analysis in S2 are used to calculate the arrester electrical stress during multiple lightning strikes, and the obtained arrester electrical stress is recorded as the arrester electrical stress of multiple lightning strikes with actual waveforms; the multiple return-to-ground lightning current parameters of the first negative polarity lightning strike of 1 / 200μs and the subsequent lightning strike of 0.25 / 100μs specified in IEC 62305-1 and GB / T 21714.1-2015 are used to calculate the arrester electrical stress, and the result is recorded as the arrester electrical stress of severe multiple lightning strikes; the current of 2.6 / 50μs specified in GB / T 50064-2014 is used to calculate the single lightning strike performance, and the result is recorded as the arrester electrical stress of a single lightning strike.

[0020] Furthermore, since the duration of multiple lightning strikes is less than the adiabatic time of the arrester, which is 1 s, the energy absorbed by the arrester when multiple lightning strikes occur can be obtained by summing the absorbed energy during each lightning strike.

[0021] Further, the S5 proposes a lightning arrester configuration scheme with sufficient margin and meeting the overvoltage suppression requirements, adjusts the lightning arrester type in the simulation model, and repeats S3 and S4 for secondary verification and adjustment, specifically:

[0022] According to the maximum value of electrical stress obtained in S4, the arrester model with continuous operating voltage, protection level and energy absorption capacity that meet the overvoltage suppression requirements is selected based on the continuous operating voltage of the system;

[0023] Build a simulation model of the adjusted and updated arrester, repeat the two steps of lightning performance verification calculation and arrester performance parameter adjustment in S3 and S4, and verify whether the arrester configuration scheme can suppress the overvoltage within the specified range under single lightning strikes and multiple lightning strikes and whether the electrical stress of the arrester is within the rated stress range.

[0024] Furthermore, the selection of the first lightning stroke and subsequent return stroke parameters of multiple lightning strokes is based on the provisions on multiple lightning current waveforms in IEC 62305-1 and GB / T21714.1-2015.

[0025] Furthermore, the different operation modes include symmetrical bipolar operation, single-stage earth return line and single-stage metal return line operation.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] The present invention aims to propose a calibration method for the insulation coordination of ±800kV converter station arresters taking into account multiple lightning strikes, analyze the influence of multiple lightning strikes on the electrical stress of converter station arresters in combination with actual lightning current parameters, more comprehensively consider the requirements for arrester performance under lightning overvoltage conditions, and improve the current design and calibration method for insulation coordination of ±800kV converter station arresters. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a work flow chart of the present invention;

[0029] Figure 2 It is the equivalent model of the smoothing reactor in the PSCAD simulation of the present invention;

[0030] FIG3( a ) is a schematic diagram of the wiring of 7 towers on the AC side of the converter station;

[0031] Fig. 3(b) is a model example of 7 towers on the AC side of the converter station in PSCAD. DETAILED DESCRIPTION

[0032] The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0033] like Figure 1 As shown, a method for checking insulation coordination of arresters in ±800kV converter stations considering multiple lightning strikes includes the following steps:

[0034] S1. According to the actual project and the high-frequency requirements of lightning overvoltage simulation calculation, a high-frequency electromagnetic transient simulation model for calculating lightning overvoltage under different operating modes is established. Different operating modes refer to the operating modes of the DC system, symmetrical bipolar operation, single-stage earth return line operation, single-stage metal return line operation, etc.

[0035] Specifically:

[0036] S11 Based on the actual engineering topology and parameters, the high-frequency model simulation method of each key equipment in the converter station is analyzed, such as Figure 2 The figure shows the high-frequency equivalent model of the smoothing reactor in this embodiment.

[0037] The key equipment mentioned above refers to smoothing reactors, filters and lightning arresters, etc.

[0038] S12 combines the actual topology of the line and tower to build a high-frequency electromagnetic transient simulation model of the 7 towers and lines on the AC / DC side of the converter station. Figure 3(a) is a wiring diagram of the 7 towers on the AC side of the converter station, where a single AC three-phase line is represented by a line, and Figure 3(b) is an example of the 7-tower model on the AC side of the converter station built in the PSCAD electromagnetic transient simulation software;

[0039] S2. Study and analyze the lightning current parameters of actual multiple lightning strikes, select typical lightning current waveform parameters and lightning strike time intervals of multiple lightning strikes, and obtain parameters that can characterize the different frequencies of ground lightning in the area where the research object is located;

[0040] The lightning current parameters include the frequency of multiple return ground lightning, the polarity of multiple return ground lightning, the lightning current amplitude, the lightning current wave front time / wave tail time and the lightning strike time interval.

[0041] Artificial lightning induction tests are carried out in various regions, and the lightning current waveform parameters obtained from each lightning induction test are not repeatable, which means they represent the region. Regarding the frequency and polarity of ground lightning, the data can be obtained through the lightning location system to form a probability distribution relationship of different values; regarding the wave front / wave tail time and time interval, the lightning current parameters obtained by the actual lightning induction of the required frequency are directly selected; regarding the lightning current amplitude, the maximum shielding current of the transmission line is calculated through the electrical geometry model according to the tower type and conductor hanging position of different projects, and the critical shielding current of the insulator breakdown after the shielding failure is simulated, and the smaller value of the two is selected as the shielding lightning current amplitude. The occurrence of lightning is random and non-repeatable, so the main influencing factor of the characterization here is the area where artificial lightning induction is carried out.

[0042] It should be noted that the lightning current data obtained from the artificial lightning induction test may not be complete even if lightning is successfully induced once. Therefore, the data in Table 1 are the subsequent return stroke currents obtained from the actual lightning induction (the first return stroke cannot be induced with current technology, so the waveform in the relevant standards is used). Table 2 is the actual lightning current, and the current waveform selected for multiple lightning strike simulation.

[0043] For example, based on the statistical data of the lightning location system in Guangdong Province from 2010 to 2021, the probability of multiple return ground lightning in Guangdong Province being 2 to 5 times is 78.12%, which can characterize the frequency characteristics of multiple return ground lightning in most of this area; negative polarity multiple return ground lightning accounts for 96.83%; some statistical data of lightning current amplitude, lightning current wave front time / wave tail time and lightning strike time interval are shown in Table 1. Therefore, the lightning current parameters in Table 2 are used as the simulation calculation parameters when 2 to 5 multiple return ground lightning strike the tower, among which I 1st ,I 2nd ,I 3rd ,I 4th and I 5th They represent the first counterattack, the second subsequent counterattack, the third subsequent counterattack, the fourth subsequent counterattack and the fifth subsequent counterattack respectively.

[0044] Table 1 Actual current parameters of subsequent return strokes caused by artificial lightning in Guangdong in 2021 (partial)

[0045]

[0046] Table 2 Current waveform parameters of 2-5 return-to-ground lightning

[0047]

[0048] S3. Simulate and analyze the residual voltage, current and absorbed energy of the arrester when multiple lightning strikes or multiple lightning strikes at different locations, including:

[0049] S31, calculating the maximum shielding failure current of different towers through the electrical geometry model and calculating the lightning withstand level of different towers through simulation, and determining the lightning current amplitude used for shielding failure calculation; taking the 1st tower closest to the converter station on the AC side of the converter station in this embodiment (hereinafter referred to as the DC side #1 tower) as an example, the maximum shielding failure current of this tower is 25kA;

[0050] S32, use the multiple return ground lightning parameters obtained from the analysis in S2 to calculate the arrester electrical stress during multiple lightning strikes, and the obtained arrester electrical stress is recorded as the arrester electrical stress of multiple lightning strikes with actual waveform; use the multiple return ground lightning current parameters specified in IEC 62305-1 and GB / T 21714.1-2015, with the first negative polarity lightning strike of 1 / 200μs and the subsequent lightning strike of 0.25 / 100μs, to calculate the arrester electrical stress, and the result is recorded as the arrester electrical stress of severe multiple lightning strikes; use the current of 2.6 / 50μs specified in GB / T 50064-2014 to calculate the single lightning strike performance, and the result is recorded as the arrester electrical stress of single lightning strike.

[0051] S4. Compare and analyze the amplitudes of the residual voltage, current and absorbed energy of the arrester under single lightning strike / multiple lightning strikes, and select the maximum value;

[0052] The specific steps for selecting the maximum value are: according to the simulation calculation results of the electrical stress amplitude under different lightning strike conditions in S3, compare and analyze the amplitude of the electrical stress of the arrester under single lightning strike / multiple lightning strikes, and select the maximum value as a reference for the arrester selection. For example, in this example, the maximum voltage amplitude of the line arrester is 1061kV, the maximum current amplitude is 26.00kA, and the maximum absorbed energy under single lightning strike is 1373kJ.

[0053] In this embodiment, the rated parameters of the first line arrester in the AC side of the converter station are shown in Table 3, and the simulation calculation results are shown in Table 4. The table only shows the simulation calculation results of two times using the actual subsequent return stroke lightning current waveform. The energy is the energy absorbed by the arrester after a single shielding failure. Since the duration of multiple lightning strikes is less than the adiabatic time of the arrester 1s, the energy absorbed by the arrester when multiple lightning strikes occur can be obtained by summing the absorbed energy during each lightning strike.

[0054] Table 3 Technical parameters of 500kV line arrester (model: Y20W1-444 / 1027)

[0055]

[0056] Table 4 Electrical stress of line arrester when different waveform lightning current strikes the #1 tower on the AC side of the converter station

[0057]

[0058]

[0059] S5. Propose a lightning arrester configuration scheme with sufficient margin and meeting the overvoltage suppression requirements, adjust the lightning arrester type in the simulation model, and repeat S3 and S4 for secondary verification and adjustment.

[0060] S51 selects the arrester model that meets the overvoltage suppression requirements based on the maximum value of the electrical stress obtained in the study of S4, taking into full consideration the margins of harmonics, high-frequency transients, etc., and in accordance with the existing arrester parameter selection principles and methods. For example, in this embodiment, after the #1 tower on the AC side of the converter station suffers a shielding failure, the residual voltage amplitude and current amplitude of each type of arrester exceed the rated stress, and in the case of multiple lightning faults, the residual voltage amplitude, current amplitude and absorbed energy of the arrester are higher than those of a single lightning fault. When a harsh waveform is used as the impulse current waveform, the absorbed energy of the line arrester will exceed the rated stress of 4444kJ of this type of arrester after suffering 5 lightning shielding failures.

[0061] S52 builds a simulation model of the updated arrester, repeats the lightning performance verification calculation and arrester performance parameter adjustment steps in S3 and S4, and verifies whether the arrester configuration scheme can suppress the overvoltage within the specified range under single and multiple lightning strikes and whether the electrical stress of the arrester is within the rated stress range. In this embodiment, the AC side line arrester of the converter station finally adopts the Y20W1-444 / 1106 model, and its lightning impulse protection level is 1106kV, which is greater than the arrester used in this embodiment (1027kV).

[0062] In other words, the verification of lightning arrester selection is to verify through simulation that when the lightning current reaches the lightning resistance level, the stress amplitude in the lightning arrester meets the requirements.

[0063] Furthermore, the margin is for the selection of the continuous operating voltage of the arrester. CCOV and PCOV should be higher than the maximum operating voltage at the installation of the arrester, and the superimposed harmonics and high-frequency transient operating voltage under severe working conditions should be considered to avoid excessive energy absorption by the arrester. This margin has no limit, and in engineering design, the parameters are selected for the next protection level.

[0064] In the prior art, the principle of lightning arrester configuration is: the overvoltage on the AC side of the converter station is limited by the AC side lightning arrester, and the overvoltage on the DC side is limited by the DC side lightning arrester.

[0065] The selection method of the present invention is to configure the arrester to a higher level when the electrical stress of the arrester obtained by simulation is slightly greater than a certain level of protection, because a margin for harmonics should be considered.

[0066] The advantages of the present invention are as follows: according to actual current parameters of multiple return ground lightning in different regions, lightning currents that can characterize actual multiple lightning strikes are selected for simulation calculation, so as to simulate multiple lightning intrusion wave overvoltage conditions that are more in line with actual conditions; at the same time, the single lightning strike specified in the existing standard GB / T 50064-2014, the severe multiple lightning strikes specified in the standards IEC 62305-1 and GB / T21714.1-2015, and the actual multiple lightning strikes are considered, and the requirements of the actual lightning strike fault conditions on the lightning performance of the arrester are more comprehensively analyzed, and a lightning arrester selection scheme that can effectively suppress the single lightning overvoltage and the multiple lightning overvoltage is proposed, so as to reduce the lightning strike accident rate of the arrester in the converter station.

[0067] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A ±800kV converter station arrester insulation coordination verification method considering multiple lightning strikes, characterized in that: include: S1. According to the high-frequency requirements of actual engineering and lightning overvoltage simulation calculation, a high-frequency electromagnetic transient simulation model for calculating lightning overvoltage under different operating modes is built; S2. Study and analyze the lightning current parameters of multiple lightning strikes, select the lightning current waveform parameters and lightning strike time intervals of multiple lightning strikes, and obtain the parameters that can characterize the different frequencies of ground lightning in the area where the research object is located; S3, simulation analysis of the residual voltage, current and absorbed energy of the arrester when multiple lightning strikes / multiple lightning strikes at different positions; S4. Compare and analyze the amplitudes of the residual voltage, current and absorbed energy of the arrester under single lightning strike / multiple lightning strikes, and select the maximum value; S5. Propose a lightning arrester configuration scheme with sufficient margin and meeting the overvoltage suppression requirements, adjust the lightning arrester type in the simulation model, and repeat S3 and S4 for secondary verification and adjustment.

2. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: S1: According to the actual project and the high-frequency requirements of lightning overvoltage simulation calculation, a high-frequency electromagnetic transient simulation model for calculating lightning overvoltage under different operating modes is built, specifically: S11 Based on the actual engineering topology and parameters, the high-frequency model simulation method of each key equipment in the converter station is analyzed; S12 combines the actual topology of the line and tower to build a high-frequency electromagnetic transient simulation model of 7 towers and lines on the AC / DC side of the converter station.

3. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: S2: Study and analyze the lightning current parameters of actual multiple lightning strikes, and select typical multiple lightning strike lightning current waveform parameters and lightning strike time intervals, specifically: The lightning current parameters of multiple return-to-ground lightning obtained by artificial lightning induction are analyzed. The lightning current parameters include the frequency of multiple return-to-ground lightning, the polarity of multiple return-to-ground lightning, the lightning current amplitude, the lightning current wave front time / wave tail time and the lightning strike time interval. The parameters that can characterize the ground lightning of different frequencies in the area where the research object is located are selected to provide conditions for subsequent simulation calculations.

4. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: S3, simulation analysis of the residual voltage, current and absorbed energy of the arrester when multiple lightning strikes / multiple lightning strikes at different positions, specifically: Calculate the maximum shielding failure current of different towers through electrical geometry model and calculate the lightning withstand level of different towers through simulation to determine the lightning current amplitude used for shielding failure calculation; The multiple return-to-ground lightning parameters obtained by the analysis in S2 are used to calculate the arrester electrical stress during multiple lightning strikes, and the obtained arrester electrical stress is recorded as the arrester electrical stress during multiple lightning strikes with actual waveforms; The multiple return ground lightning current parameters of the first negative polarity lightning stroke of 1 / 200μs and the subsequent lightning stroke of 0.25 / 100μs specified in IEC 62305-1 and GB / T21714.1-2015 are used to calculate the electrical stress of the lightning arrester, and the result is recorded as the electrical stress of the lightning arrester under severe multiple lightning protection strokes; the current of 2.6 / 50μs specified in GB / T 50064-2014 is used to calculate the single lightning stroke performance, and the result is recorded as the electrical stress of the lightning arrester under single lightning protection strokes.

5. The ±800kV converter station arrester insulation coordination verification method according to claim 4 is characterized in that: Since the duration of multiple lightning strikes is less than the adiabatic time of the arrester, which is 1s, the energy absorbed by the arrester when multiple lightning strikes occur can be obtained by summing the absorbed energy during each lightning strike.

6. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: S5, proposes a lightning arrester configuration scheme with sufficient margin and meeting the overvoltage suppression requirements, adjusts the lightning arrester type in the simulation model, and repeats S3 and S4 for secondary verification and adjustment, specifically: According to the maximum value of electrical stress obtained in S4, the arrester model with continuous operating voltage, protection level and energy absorption capacity that meet the overvoltage suppression requirements is selected based on the continuous operating voltage of the system; Build a simulation model of the adjusted and updated arrester, repeat the two steps of lightning performance verification calculation and arrester performance parameter adjustment in S3 and S4, and verify whether the arrester configuration scheme can suppress the overvoltage within the specified range under single lightning strikes and multiple lightning strikes and whether the electrical stress of the arrester is within the rated stress range.

7. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: The selection of the first lightning stroke and subsequent return stroke parameters of multiple lightning strokes is based on the provisions on multiple lightning current waveforms in IEC 62305-1 and GB / T 21714.1-2015.

8. The ±800kV converter station arrester insulation coordination verification method according to claim 1 is characterized in that: The different operation modes include symmetrical bipolar operation, single-stage earth return line and single-stage metal return line operation.

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