Air clear distance calculation method and system for offshore commutation platform

Abstract

The invention discloses an air clear distance calculation method and system for an offshore converter platform, and the method comprises the steps: calculating the lightning overvoltage and operation overvoltage of a to-be-measured point through the collected weather and meteorological data of the offshore converter platform; under a preset artificial pollution test condition, the pollution flashover voltage of the to-be-tested insulator is measured; according to a preset empirical formula, the minimum air clear distances under the pollution flashover voltage, the lightning overvoltage and the operation overvoltage are subjected to iterative calculation, and the maximum value is selected from the minimum air clear distances to serve as the optimal air clear distance; and according to the optimal air clear distance, designing the layout of the valve hall electrical equipment of the offshore converter platform. According to the method, the optimal air clear distance is calculated under the condition that the safety of the converter platform is guaranteed, and the total construction cost is reduced by effectively reducing the overall size of the offshore converter station.

Description

Technical Field

[0001] The present application belongs to the field of flexible direct current technology, and specifically relates to a method and system for calculating air clearance of an offshore converter platform. Background Art

[0002] As an important part of the offshore flexible DC transmission project, the offshore flexible DC converter station plays an important role in realizing large-capacity and long-distance offshore wind power transmission. For the offshore flexible DC converter station, the valve hall is one of the largest and most important areas in the platform. Its scale and layout largely determine the size and platform layout of the entire converter station. Therefore, the design of the valve hall has a great impact on the investment and construction cost of the offshore flexible DC converter station. Among them, the layout of the electrical equipment in the valve hall needs to be designed in combination with the requirements of the fully enclosed, compact, lightweight and stacked platform layout. Therefore, it is necessary to determine the lightning arrester protection level and equipment insulation level of the equipment in the converter station, and then study the air clearance between the equipment and the surrounding grounding body to reduce the construction cost of the offshore converter station.

[0003] The existing calculation methods for the air clearance of the converter station valve hall are mainly aimed at the geographical environment of high altitude areas, and there is almost no reference data for the calculation method of the air clearance of the offshore valve hall. In addition, due to the particularity of the humidity, temperature, salinity and grayscale of the offshore environment, it has a significant impact on the size of the air clearance of the valve hall design, which needs to be studied in depth. Summary of the invention

[0004] The present application proposes a method and system for calculating the air clearance of an offshore converter platform, which calculates the optimal air clearance while ensuring the safety of the converter platform, and reduces the total construction cost by effectively reducing the overall volume of the offshore converter station.

[0005] A first aspect of the present application provides a method for calculating the air clearance of an offshore converter platform, the method comprising:

[0006] Calculate the lightning overvoltage and operating overvoltage of the test point through the weather and meteorological data collected from the offshore converter platform;

[0007] Under the preset artificial pollution test conditions, measure the pollution flashover voltage of the insulator to be tested;

[0008] According to a preset empirical formula, iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the switching overvoltage, respectively, and select the maximum value from the minimum air clearances as the optimal air clearance;

[0009] Based on the optimal air clearance, the layout of the valve hall electrical equipment of the offshore converter platform is designed.

[0010] The above scheme first collects weather and meteorological data related to the temperature, humidity, salinity and grayscale of the offshore converter platform, and then calculates the lightning overvoltage and operating overvoltage based on the weather and meteorological data, fully considering the impact of the meteorological environment; then the insulator is subjected to a pollution test to obtain the pollution flashover voltage related to the grayscale and salinity, and the air clearance under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage are calculated respectively, and the largest air clearance is selected as the data basis for designing the layout of the valve hall electrical equipment of the offshore converter platform, so as to comprehensively consider the air clearance under different voltages, more comprehensively meet the safety requirements of the offshore converter platform under different operating conditions, and reduce the total construction cost by effectively reducing the overall volume of the offshore converter station while ensuring the safety of the converter platform.

[0011] In a possible implementation method of the first aspect, the lightning overvoltage and the operating overvoltage of the point to be measured are calculated by collecting weather and meteorological data of the offshore converter platform, specifically:

[0012] Acquiring weather and meteorological data of the offshore converter platform, and calculating the critical impulse flashover voltage of the air gap in the actual atmospheric environment according to the weather and meteorological data;

[0013] According to the preset first ratio and the critical impulse flashover voltage, the lightning overvoltage in the actual atmospheric environment is obtained;

[0014] According to the preset second ratio and the critical impulse flashover voltage, the operating overvoltage in the actual atmospheric environment is obtained;

[0015] The lightning overvoltage and the operating overvoltage are processed by using a g parameter method to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions.

[0016] The above scheme first calculates the critical impulse flashover voltage of the air gap in the actual atmospheric environment, and obtains the lightning overvoltage and the operating overvoltage therein at a preset ratio. Then, the lightning overvoltage and the operating overvoltage are processed by the g parameter method, and the discharge characteristics of the air gap are corrected by considering different meteorological conditions to ensure that the corrected results are more in line with the actual situation. At the same time, the data under the actual situation is converted into data under standard atmospheric conditions to facilitate subsequent calculations.

[0017] In a possible implementation method of the first aspect, the lightning overvoltage and the operating overvoltage are processed using a g parameter method to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions, specifically:

[0018] Obtaining humidity data and temperature data according to the weather and meteorological data;

[0019] Based on the g parameter method, a humidity correction coefficient is set according to the humidity data, and a temperature correction coefficient is set according to the temperature data;

[0020] Determine the atmospheric correction factor based on the humidity correction factor and the temperature correction factor;

[0021] The lightning overvoltage and the operating overvoltage are processed respectively by the atmospheric correction coefficient to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions.

[0022] The above scheme takes into account the influence of humidity and temperature on the discharge characteristics of the air gap respectively, and corrects the lightning overvoltage and switching overvoltage data by setting the humidity correction coefficient and the temperature correction coefficient, so that the corrected results are more in line with the actual situation and the data accuracy is improved.

[0023] In a possible implementation method of the first aspect, the lightning overvoltage and the operating overvoltage are specifically:

[0024] The specific expression of the lightning overvoltage is:

[0025]

[0026] Where U 50-thun is the lightning overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-thum Lightning impulse insulation level of electrical equipment on offshore converter platforms, K q is the atmospheric correction factor;

[0027] The specific expression of the operating overvoltage is:

[0028]

[0029] Where U 50-op is the operating overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-op Operation impulse insulation level for electrical equipment of offshore converter platforms, K q is the atmospheric correction factor.

[0030] In a possible implementation method of the first aspect, under preset artificial pollution test conditions, the pollution flashover voltage of the insulator to be tested is measured, specifically:

[0031] Based on the artificial pollution test conditions, a preset uniform voltage boost method is used to perform several voltage boost flashover tests on the insulator to be tested, and a flashover voltage value of each voltage boost flashover test is obtained;

[0032] After each voltage-up flashover test, the insulator to be tested is processed, and the ash density influence index and salt density influence index of each voltage-up flashover test are obtained respectively by using the preset ash density calculation formula and salt density calculation formula;

[0033] The flashover voltage value, ash density influence index and salt density influence index are fitted and analyzed by the least square method to obtain the pollution flashover voltage of the insulator to be tested.

[0034] The above scheme conducts several voltage-up flashover tests on the insulator under artificial pollution test conditions to obtain the corresponding flashover voltage value. Then, the ash density influence index and salt density influence index of each voltage-up flashover test are calculated based on the insulator to be tested, and the pollution flashover voltage is obtained, which provides data support for subsequent research on the influence of gray and salinity on air clearance.

[0035] In a possible implementation method of the first aspect, the flashover voltage value of each boost flashover test is obtained, specifically:

[0036] Record the experimental data of each voltage-boosting flashover test;

[0037] A first threshold number of lowest values ​​are selected from the experimental data, and an average value of the lowest values ​​is used as the flashover voltage value.

[0038] In a possible implementation method of the first aspect, according to a preset empirical formula, the minimum air clearances under the pollution flashover voltage, the lightning overvoltage, and the switching overvoltage are iteratively calculated respectively, and a maximum value is selected from the minimum air clearances as the optimal air clearance, specifically:

[0039] Calculate the pollution flashover voltage according to a preset air clearance-voltage relationship formula to obtain a first minimum air clearance under the pollution flashover voltage;

[0040] According to a preset air clearance-voltage relationship formula, by iterating the iteration factor, the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the switching overvoltage are calculated;

[0041] A maximum value is selected from the first minimum air clearance, the second minimum air clearance and the third minimum air clearance as the optimal air clearance.

[0042] The above scheme calculates the minimum air clearance under pollution flashover voltage, lightning overvoltage and switching overvoltage according to the preset air clearance-voltage relationship formula. It also iteratively calculates lightning overvoltage and switching overvoltage, and fully considers the impact of the micro-meteorological environment on the air clearance. Finally, the maximum value is selected from all the air clearance data as the optimal air clearance, which can effectively ensure the safety of the converter platform.

[0043] In a possible implementation method of the first aspect, according to a preset air clearance-voltage relationship formula, by iterating an iteration factor, the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the switching overvoltage are calculated, specifically:

[0044] According to a preset air clearance-voltage relationship formula and an iteration factor, the lightning overvoltage and the switching overvoltage are iteratively calculated, and a corresponding air clearance result is obtained in each iterative calculation;

[0045] After each iterative calculation is completed, the iteration factor is updated according to the air clearance result obtained this time and the preset iterative update formula, and the updated iteration factor is used in the next iterative calculation;

[0046] When the difference between the air clearance results obtained by two adjacent iterative calculations is less than a second threshold, the iterative calculation is stopped, and the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the operating overvoltage are determined.

[0047] In a possible implementation method of the first aspect, the iterative update formula is specifically:

[0048]

[0049] In the formula, g is the iteration factor, U 50 is the lightning overvoltage or the operating overvoltage, d is the air clearance result, δ is the air relative density, and k is the proportional factor.

[0050] A second aspect of the present application provides an air clearance calculation system for an offshore converter platform, the system comprising: an impulse test voltage acquisition module, a pollution flashover voltage acquisition module, an optimal air clearance acquisition module and a valve hall layout design module;

[0051] The impulse test voltage acquisition module is used to calculate the lightning overvoltage and operating overvoltage of the test point through the collected weather and meteorological data of the offshore converter platform;

[0052] The pollution flashover voltage acquisition module is used to measure the pollution flashover voltage of the insulator to be tested under preset artificial pollution test conditions;

[0053] The optimal air clearance acquisition module is used to iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage according to a preset empirical formula, and select the maximum value from the minimum air clearances as the optimal air clearance;

[0054] The valve hall layout design module is used to design the layout of the valve hall electrical equipment of the offshore converter platform according to the optimal air clearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the implementation manner will be briefly introduced below. Obviously, the drawings described below are only some implementation manners of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 This is a specific flow chart of a method for calculating the air clearance of an offshore converter platform provided in a certain embodiment of the present application;

[0057] Figure 2 It is a wiring diagram of a test platform for calculating the air clearance of an offshore converter platform provided in a certain embodiment of the present application;

[0058] Figure 3 It is a structural diagram of an air clearance calculation system for an offshore converter platform provided in a certain embodiment of the present application. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0060] It should be understood that the step numbers used in this article are only for the convenience of description and are not intended to limit the order in which the steps are executed.

[0061] First embodiment

[0062] The valve hall is one of the largest and most important areas in the offshore converter platform. Its size and layout largely determine the size and platform layout of the entire converter station. Therefore, the design of the valve hall has a great impact on the investment and construction costs of the offshore flexible DC converter station. In order to improve the electric field distribution, large-sized grading rings or shielding rings are installed on the top and protruding corners of each electrical equipment. Therefore, the air gap between the equipment and the surrounding grounding body is actually the minimum air clearance formed by the grading ring or shielding ring of the equipment and the surrounding walls or other grounding bodies. In theory, in order to reduce the volume of the valve hall, the air clearance between the electrical equipment and the grounding body is generally designed to be as small as possible. However, if the air clearance is too small, it is easy to cause the high-voltage end of the electrical equipment to be in a high-voltage state, causing damage to the equipment or even the platform.

[0063] Therefore, the main research purpose of the embodiments of the present application is to calculate the optimal air clearance while ensuring the safety of the converter platform, so as to design the overall volume of the offshore converter station to reduce the total construction cost.

[0064] like Figure 1 As shown, Figure 1 A specific flow chart of a method for calculating the air clearance of an offshore converter platform is provided for a certain embodiment of the present application. The method for calculating the air clearance of an offshore converter platform of this embodiment includes steps S1 to S4, which are described in detail as follows:

[0065] Step S1, calculating the lightning overvoltage and operating overvoltage of the test point by collecting the weather and meteorological data of the offshore converter platform.

[0066] In the embodiment of the present application, the experimental background is the Y / D valve side of the high-potential converter transformer in the 1100kV threshold hall.

[0067] First, obtain the weather and meteorological data of the offshore converter platform, including humidity data and temperature data, to determine the actual atmospheric environment. For example, the data obtained based on the experimental background of the embodiment of the present application is as follows:

[0068] Equipment environment Altitude / m Valve hall temperature / ℃ Valve hall humidity / % In valve hall, with air conditioning 0 5-60 5-60

[0069] Table 1

[0070] Then, the critical impulse flashover voltage of the air gap in the actual atmospheric environment is calculated according to the weather and meteorological data.

[0071] The specific expression of the critical impulse flashover voltage is:

[0072]

[0073] Where U 50 is the 50% critical impulse flashover voltage of the air gap, in kV; U ω K is the lightning / switching impulse insulation level of electrical equipment, in kV; ω is the margin factor, K q is the atmospheric correction coefficient, and σ is the variation coefficient of impulse discharge voltage of air gap.

[0074] The above σ is the preset first ratio and second ratio. In the embodiment of the present application, 3% is taken for lightning impulse and 6% is taken for operation impulse. Then the lightning overvoltage and operation overvoltage in the actual atmospheric environment can be obtained, and the specific expression is:

[0075]

[0076] Where U 50-thun is the lightning overvoltage under standard atmospheric conditions, Kω is the margin factor, U ω-thum Lightning impulse insulation level of electrical equipment on offshore converter platforms, K q is the atmospheric correction factor.

[0077]

[0078] Where U 50-op is the operating overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-op Operation impulse insulation level for electrical equipment of offshore converter platforms, K q is the atmospheric correction factor.

[0079] Among them, the atmospheric correction coefficient is used to correct the coefficient of the influence of atmospheric conditions on the test voltage. In the embodiment of the present application, it can be used to correct the lightning overvoltage and the operating overvoltage to obtain a more accurate air clearance under actual conditions and improve data accuracy.

[0080] Therefore, the g-parameter method is also used to process the atmospheric correction coefficient to achieve accuracy verification of the lightning overvoltage and the operating overvoltage.

[0081] For the atmospheric correction factor K q , there is K q =k1*k2, k1 is the atmospheric density correction factor, k2 is the humidity correction factor. The values ​​of k1 and k2 are derived from the acquired weather and meteorological data, and the specific relationship expression is:

[0082] k1=δ m ;

[0083]

[0084] k2=k w ;

[0085] Wherein, δ is the relative density of air, m is the first influencing factor, b is the atmospheric pressure of the actual atmospheric environment, the unit is kPa, b0 is the atmospheric pressure under standard atmospheric conditions, the value is 101.3 kPa; t is the air temperature, the unit is ℃; t0 is the temperature under standard atmospheric conditions, the value is 20℃; w is the second influencing factor, k is determined by a function depending on the impact test and the ratio of absolute humidity to air relative density h / δ, which is called the proportional factor here.

[0086] Optionally, the function of the impact test is k=1+0.014(h / δ-11).

[0087] It can be seen from the above formula that the atmospheric density correction coefficient is actually related to temperature, so it is also called the temperature correction coefficient in the embodiment of the present application. The value of the atmospheric correction coefficient can be determined based on k1 and k2.

[0088] Furthermore, the values ​​of the first influencing factor and the second influencing factor in the above formula are adjusted by the g parameter method to achieve the adjustment of the atmospheric correction coefficient. Correcting the discharge characteristics of the air gap can effectively consider the impact of different meteorological conditions on the discharge characteristics and ensure that the calculation results are closer to the actual situation. In the embodiment of the present application, the parameter g is introduced to determine the values ​​of m and w, and the definition of g is as follows:

[0089]

[0090] Where U 50 is the lightning overvoltage or the operating overvoltage, d is the air clearance result, δ is the air relative density, and k is the proportional factor.

[0091] Because the optimal air clearance will be calculated by iterating the parameter g in subsequent calculations, the parameter g can also be called an iteration factor.

[0092] Specifically, the functional relationship between the iteration factor and m and w is as follows:

[0093] g m w <0.2 0 0 0.2～1.0 g(g-0.2) / 0.8 g(g-0.2) / 0.8 1.0～1.2 1.0 1.0 1.2～2.0 1.0 (2.2-g)(2-g) / 0.8 >2.0 1.0 0

[0094] Table 2

[0095] Therefore, according to the iteration factor g, the values ​​of the humidity correction coefficient and the temperature correction coefficient can be determined, and the value of the atmospheric correction coefficient can be further determined, so as to correct the lightning overvoltage and operating overvoltage in the actual atmospheric environment to the lightning overvoltage and operating overvoltage under standard atmospheric conditions.

[0096] Step S2, measuring the pollution flashover voltage of the insulator to be tested under preset artificial pollution test conditions.

[0097] In the embodiment of the present application, based on the artificial pollution test conditions, a pollution flashover test is performed on the insulator to be tested to measure the pollution flashover voltage. Among them, the insulator is a device installed between conductors of different potentials or between conductors and grounding parts, which can withstand voltage and mechanical stress, and plays an important role in the electrical equipment of the offshore converter station. Measuring the pollution flashover voltage of the insulator to be tested in the electrical equipment is of great significance to the evaluation of the operating safety of the offshore converter station.

[0098] The simple test diagram of the pollution flashover test is as follows: Figure 2As shown, AC is the input voltage terminal, T is a low-voltage variable ratio transformer for primary voltage boosting, B is a high-voltage transformer for secondary voltage boosting to the reference voltage value of the insulator to be tested, R is a circuit protection resistor, and C1 and C2 are constant voltage capacitors.

[0099] In the embodiment of the present application, the specific process of the pollution flashover test is as follows:

[0100] (1) After taking the insulator out of the dirty liquid, wipe the dirty liquid on the insulator steel cap with absorbent cotton, hang the insulator on the hook of the artificial fog chamber after 24 hours, start the steam pipe installed in the fog chamber to evenly generate hot fog, so that the visibility of the artificial fog chamber is less than 1m;

[0101] (2) When the insulator is fully wetted in the hot mist and the pollution layer solution on its surface has not dripped, the insulator is subjected to a flashover test using the uniform voltage increase method; each insulator is subjected to at least 4 flashover tests;

[0102] (3) Carry out flashover tests on three insulators under the same test conditions. Select the three lowest flashover voltage values ​​from the four flashover voltage values ​​recorded for each insulator. That is, take the average value of the nine flashover voltage values ​​of the three insulators as the flashover voltage value of the insulator under the pollution conditions.

[0103] After each flashover test, the insulator is rotated axially by 360 / n degrees, where n is the number of flashover tests currently being conducted. When the pollution layer of the insulator is saturated and wet again and the pollution layer solution on its surface does not drip, the voltage is increased again to perform the flashover test.

[0104] Furthermore, after each flashover test, the insulator is rinsed with distilled water, the washed dirty liquid is collected, and the dirty liquid is filtered through filter paper, and the dirt on the filter paper is dried and weighed to calculate the ash density impact index and salt density impact index. Among them, the ash density is the density of insoluble sediments on the surface area of ​​the insulator, and the salt density is the amount of sodium chloride attached to the surface area of ​​the insulator per square centimeter, which is equivalent to the content of conductive substances in the dirt. Since the salt density is only related to the amount, composition and properties of the insulator, the salt density can characterize the conductivity of the soluble substances in the dirt layer. Both are important parameters for characterizing the degree of dirt on the external insulation of electrical equipment, and are of great significance for evaluating and preventing flashover accidents of electrical equipment.

[0105] The gray density influence index can be obtained according to the preset gray density calculation formula. The specific calculation formula is:

[0106]

[0107] Where ρ1 is the gray density influence index, W fW is the weight of the filter paper containing the dirt after drying, in grams; i is the initial weight of the filter paper after drying, and A is the contaminated area on the insulator surface.

[0108] The salt density impact index can be obtained according to the preset salt density calculation formula. The specific calculation formula is:

[0109]

[0110] Where ρ2 is the salt density influence index, S a is the salt content, V is the volume of distilled water, and A is the contaminated area on the insulator surface.

[0111] Exemplarily, the embodiment of the present application performs flashover tests on 1100 kV composite insulators with arbitrary ash density and salt density. The test results are shown in the following table, with a total of 10 groups of valid data:

[0112] <![CDATA[ρ1(mg / cm 2 )]]> <![CDATA[ρ2(mg / cm 2 )]]> <![CDATA[U f / kV]]> <![CDATA[ρ1(mg / cm 2 )]]> <![CDATA[ρ2(mg / cm 2 )]]> <![CDATA[U f / kV <!-- 7 -->]]> 0.55 0.09 1542.8 1.62 0.21 1208.8 0.62 0.32 1322.1 2.32 0.46 1083.8 1.80 0.08 1329.7 3.89 0.29 1032.0 1.59 0.11 1295.0 3.11 0.48 1020.0 1.41 0.23 1250.7 4.49 0.32 1005.0

[0113] Table 3

[0114] Among them, U f is the flashover voltage value.

[0115] Assume U f Satisfies the functional relationship with ρ1 and ρ2 The least square method was used to fit the above test results and obtain U f The relationship between ρ1 and ρ2 is Here, the average value of ρ1 and ρ2 is used as the reference value for calculation, and the final pollution flashover voltage of the insulator to be tested is 1141.103.kV. O is the reference voltage level, which is set to 1100 kV in the embodiment of the present application.

[0116] Step S3, according to a preset empirical formula, iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the switching overvoltage respectively, and select the maximum value from the minimum air clearances as the optimal air clearance.

[0117] In the embodiment of the present application, it is first assumed that the initial value of the first influencing factor m and the second influencing factor w is 0, the threshold room temperature is 25° C., the poster height is 0, and the threshold room relative humidity is 60%, and the initial value of the atmospheric correction coefficient is calculated.

[0118] Then calculate the 50% impulse discharge voltage withstand voltage of the air gap as the lightning impulse insulation level and the switching impulse insulation level to clarify the lightning arrester configuration and insulation level of the offshore converter station.

[0119] According to the preset air clearance-voltage relationship formula (which can be an empirical formula), the air clearance for lightning overvoltage and switching overvoltage can be obtained, as follows:

[0120]

[0121]

[0122] Where d1 is the air clearance of lightning overvoltage, U 50-thun is the lightning overvoltage under standard atmospheric conditions, K is the electrode shape coefficient, different coefficients represent different electrode shapes, and the larger the shape, the more uniform the electric field. Since the influence of the motor shape is not considered in the embodiment of the present application, K is fixed to 1, so that a larger air clearance can be obtained to ensure a larger safety margin; d2 is the air clearance of the operating overvoltage, U 50-op It is the operating overvoltage under standard atmospheric conditions.

[0123] In the embodiment of the present application, the operation impulse insulation level of the Y / D valve side of the low-potential converter transformer is calculated to be 1105 kV. In general, in order to ensure safe operation, the larger air clearance between the lightning impulse and the operation impulse calculation value is taken as the minimum safe air clearance of the point. Due to the saturation effect of the gap under the operation impulse, the air clearance required under the operation voltage in the valve hall is much larger than the air clearance determined by the lightning impulse, so the air clearance of the operation overvoltage is generally taken.

[0124] In order to improve the calculation accuracy, the embodiment of the present application needs to iteratively calculate the air clearance of lightning overvoltage and switching overvoltage through an iterative factor, so as to obtain an air clearance value that is more in line with the actual situation, and effectively reduce the air clearance of the offshore platform converter station and the overall platform volume.

[0125] Specifically, assuming that the initial values ​​of the first influencing factor m and the second influencing factor w are 0, the threshold room temperature is 25°C, the poster height is 0, and the threshold room relative humidity is 60%, the initial value of the atmospheric correction coefficient is calculated as follows:

[0126]

[0127]

[0128] k = 1 + 0.01 (h / g-11) = 2.267;

[0129]

[0130] Wherein, h is absolute humidity, R is relative humidity, which is 60% here. Since the first and second influencing factors are both defined as 0, the iteration factor g is 0.1, and k1 and k2 are both 1.

[0131] Then the lightning overvoltage and switching overvoltage of the first iteration and the corresponding air clearance results are calculated. If the difference between the air clearance results calculated in two consecutive iterations is not less than the second threshold, the iteration continues and the air clearance result calculated the most recently is substituted into A new iteration factor g is calculated, and then updated k1 and k2 are obtained according to Table 2 provided in the embodiment of the present application, and the atmospheric correction coefficient is further updated for the next iterative calculation until the iteration stops.

[0132] As mentioned above, in order to ensure the safe operation of the system as much as possible, the air clearance of the operating overvoltage is generally taken. Therefore, after the minimum air clearance of the operating overvoltage is obtained, the minimum air clearance of the flashover voltage is calculated according to the preset air clearance-voltage relationship formula, and the minimum air clearance of the two is compared, and the maximum value is selected as the optimal air clearance.

[0133] Step S4: designing the layout of the valve hall electrical equipment of the offshore converter platform according to the optimal air clearance.

[0134] In the embodiment of the present application, the air clearance between the electrical equipment to be tested and the grounding body, etc. is designed according to the obtained optimal air clearance to reduce the volume of the threshold hall.

[0135] Implementing the embodiments of the present application has the following beneficial effects:

[0136] The embodiment of the present application first collects weather and meteorological data related to the temperature, humidity, salinity and grayscale of the offshore converter platform, and then calculates the lightning overvoltage and the operating overvoltage based on the weather and meteorological data, fully considering the influence of the meteorological environment; then, a pollution test is performed on the insulator to obtain the pollution flashover voltage related to the grayscale and salinity, and the air clearance under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage are calculated respectively, and the maximum air clearance is selected as the data basis for designing the layout of the valve hall electrical equipment of the offshore converter platform, so as to comprehensively consider the air clearance under different voltages, more comprehensively meet the safety requirements of the offshore converter platform under different operating conditions, and reduce the total construction cost by effectively reducing the overall volume of the offshore converter station while ensuring the safety of the converter platform.

[0137] Second embodiment

[0138] Further, in order to execute the air clearance calculation system of the offshore converter platform corresponding to the above method embodiment to achieve the corresponding functions and technical effects, Figure 3 A structural diagram of an air clearance calculation system for an offshore converter platform is provided. For ease of description, only the parts related to this embodiment are shown. The air clearance calculation system for an offshore converter platform provided in the embodiment of the present application includes:

[0139] The impulse test voltage acquisition module 201 is used to calculate the lightning overvoltage and operating overvoltage of the test point through the collected weather and meteorological data of the offshore converter platform.

[0140] In an embodiment of the present application, weather and meteorological data of an offshore converter platform are obtained, and a critical impulse flashover voltage of an air gap in an actual atmospheric environment is calculated based on the weather and meteorological data; the lightning overvoltage in the actual atmospheric environment is obtained based on a preset first ratio and the critical impulse flashover voltage; the operating overvoltage in the actual atmospheric environment is obtained based on a preset second ratio and the critical impulse flashover voltage; the lightning overvoltage and the operating overvoltage are processed using a g parameter method to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions.

[0141] The pollution flashover voltage acquisition module 202 is used to measure the pollution flashover voltage of the insulator to be tested under preset artificial pollution test conditions.

[0142] In an embodiment of the present application, based on the artificial pollution test conditions, a preset uniform boost method is used to perform several boost flashover tests on the insulator to be tested, and the flashover voltage value of each boost flashover test is obtained; after each boost flashover test, the insulator to be tested is processed, and the ash density influence index and salt density influence index of each boost flashover test are respectively obtained by the preset ash density calculation formula and salt density calculation formula; the flashover voltage value, ash density influence index and salt density influence index are fitted and analyzed by the least squares method to obtain the pollution flashover voltage of the insulator to be tested.

[0143] The optimal air clearance acquisition module 203 is used to iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage according to a preset empirical formula, and select the maximum value from the minimum air clearances as the optimal air clearance.

[0144] In an embodiment of the present application, the pollution flashover voltage is calculated according to a preset air clearance-voltage relationship formula to obtain a first minimum air clearance under the pollution flashover voltage; according to a preset air clearance-voltage relationship formula, the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the operational overvoltage are calculated by iterating an iteration factor; and the maximum value among the first minimum air clearance, the second minimum air clearance and the third minimum air clearance is selected as the optimal air clearance.

[0145] The valve hall layout design module 204 is used to design the layout of the valve hall electrical equipment of the offshore converter platform according to the optimal air clearance.

[0146] In some embodiments, the impulse test voltage acquisition module 201 further includes:

[0147] In the embodiment of the present application, the experimental background is the Y / D valve side of the high-potential converter transformer in the 1100kV threshold hall.

[0148] First, obtain the weather and meteorological data of the offshore converter platform, including humidity data and temperature data, to determine the actual atmospheric environment. For example, the data obtained based on the experimental background of the embodiment of the present application is as follows:

[0149] Equipment environment Altitude / m Valve hall temperature / ℃ Valve hall humidity / % In valve hall, with air conditioning 0 5-60 5-60

[0150] Table 1

[0151] Then, the critical impulse flashover voltage of the air gap in the actual atmospheric environment is calculated according to the weather and meteorological data.

[0152] The specific expression of the critical impulse flashover voltage is:

[0153]

[0154] Where U 50 is the 50% critical impulse flashover voltage of the air gap, in kV; U ω K is the lightning / switching impulse insulation level of electrical equipment, in kV; ω is the margin factor, K q is the atmospheric correction coefficient, and σ is the variation coefficient of impulse discharge voltage of air gap.

[0155] The above σ is the preset first ratio and second ratio. In the embodiment of the present application, 3% is taken for lightning impulse and 6% is taken for operation impulse. Then the lightning overvoltage and operation overvoltage in the actual atmospheric environment can be obtained, and the specific expression is:

[0156]

[0157] Where U 50-thun is the lightning overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-thum Lightning impulse insulation level of electrical equipment on offshore converter platforms, K q is the atmospheric correction factor.

[0158]

[0159] Where U 50-op is the operating overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-op Operation impulse insulation level for electrical equipment of offshore converter platforms, K q is the atmospheric correction factor.

[0160] Among them, the atmospheric correction coefficient is used to correct the coefficient of the influence of atmospheric conditions on the test voltage. In the embodiment of the present application, it can be used to correct the lightning overvoltage and the operating overvoltage to obtain a more accurate air clearance under actual conditions and improve data accuracy.

[0161] Therefore, the g-parameter method is also used to process the atmospheric correction coefficient to achieve accuracy verification of the lightning overvoltage and the operating overvoltage.

[0162] For the atmospheric correction factor K q , there is K q =k1*k2, k1 is the atmospheric density correction factor, k2 is the humidity correction factor. The values ​​of k1 and k2 are derived from the acquired weather and meteorological data, and the specific relationship expression is:

[0163] k1=δ m ;

[0164]

[0165] k2=k w ;

[0166] Wherein, δ is the relative density of air, m is the first influencing factor, b is the atmospheric pressure of the actual atmospheric environment, the unit is kPa, b0 is the atmospheric pressure under standard atmospheric conditions, the value is 101.3 kPa; t is the air temperature, the unit is ℃; t0 is the temperature under standard atmospheric conditions, the value is 20℃; w is the second influencing factor, k is determined by a function depending on the impact test and the ratio of absolute humidity to air relative density h / δ, which is called the proportional factor here.

[0167] Optionally, the function of the impact test is k=1+0.014(h / δ-11).

[0168] It can be seen from the above formula that the atmospheric density correction coefficient is actually related to temperature, so it is also called the temperature correction coefficient in the embodiment of the present application. The value of the atmospheric correction coefficient can be determined based on k1 and k2.

[0169] Furthermore, the values ​​of the first influencing factor and the second influencing factor in the above formula are adjusted by the g parameter method to achieve the adjustment of the atmospheric correction coefficient. Correcting the discharge characteristics of the air gap can effectively consider the impact of different meteorological conditions on the discharge characteristics and ensure that the calculation results are closer to the actual situation. In the embodiment of the present application, the parameter g is introduced to determine the values ​​of m and w, and the definition of g is as follows:

[0170]

[0171] Where U 50is the lightning overvoltage or the operating overvoltage, d is the air clearance result, δ is the air relative density, and k is the proportional factor.

[0172] Because the optimal air clearance will be calculated by iterating the parameter g in subsequent calculations, the parameter g can also be called an iteration factor.

[0173] Specifically, the functional relationship between the iteration factor and m and w is as follows:

[0174] g m w <0.2 0 0 0.2～1.0 g(g-0.2) / 0.8 g(g-0.2) / 0.8 1.0～1.2 1.0 1.0 1.2～2.0 1.0 (2.2-g)(2-g) / 0.8 >2.0 1.0 0

[0175] Table 2

[0176] Therefore, according to the iteration factor g, the values ​​of the humidity correction coefficient and the temperature correction coefficient can be determined, and the value of the atmospheric correction coefficient can be further determined, so as to correct the lightning overvoltage and operating overvoltage in the actual atmospheric environment to the lightning overvoltage and operating overvoltage under standard atmospheric conditions.

[0177] In some embodiments, the impulse test voltage acquisition module 201 further includes:

[0178] In the embodiment of the present application, based on the artificial pollution test conditions, a pollution flashover test is performed on the insulator to be tested to measure the pollution flashover voltage. Among them, the insulator is a device installed between conductors of different potentials or between conductors and grounding parts, which can withstand voltage and mechanical stress, and plays an important role in the electrical equipment of the offshore converter station. Measuring the pollution flashover voltage of the insulator to be tested in the electrical equipment is of great significance to the evaluation of the operating safety of the offshore converter station.

[0179] In the embodiment of the present application, the specific process of the pollution flashover test is as follows:

[0180] (4) After taking the insulator out of the dirty liquid, wipe the dirty liquid on the insulator steel cap with absorbent cotton, hang the insulator on the hook of the artificial fog chamber after 24 hours, start the steam pipe installed in the fog chamber to evenly generate hot fog, so that the visibility of the artificial fog chamber is less than 1m;

[0181] (5) When the insulator is fully wetted in the hot mist and the pollution solution on its surface has not dripped, the insulator is subjected to a flashover test using the uniform voltage increase method; each insulator is subjected to at least 4 flashover tests;

[0182] (6) Carry out flashover tests on three insulators under the same test conditions. Select the three lowest flashover voltage values ​​from the four flashover voltage values ​​recorded for each insulator. That is, take the average value of the nine flashover voltage values ​​of the three insulators as the flashover voltage value of the insulator under the pollution conditions.

[0183] After each flashover test, the insulator is rotated axially by 360 / n degrees, where n is the number of flashover tests currently being conducted. When the pollution layer of the insulator is saturated and wet again and the pollution layer solution on its surface does not drip, the voltage is increased again to perform the flashover test.

[0184] Furthermore, after each flashover test, the insulator is rinsed with distilled water, the washed dirty liquid is collected, and the dirty liquid is filtered through filter paper, and the dirt on the filter paper is dried and weighed to calculate the ash density impact index and salt density impact index. Among them, the ash density is the density of insoluble sediments on the surface area of ​​the insulator, and the salt density is the amount of sodium chloride attached to the surface area of ​​the insulator per square centimeter, which is equivalent to the content of conductive substances in the dirt. Since the salt density is only related to the amount, composition and properties of the insulator, the salt density can characterize the conductivity of the soluble substances in the dirt layer. Both are important parameters for characterizing the degree of dirt on the external insulation of electrical equipment, and are of great significance for evaluating and preventing flashover accidents of electrical equipment.

[0185] The gray density influence index can be obtained according to the preset gray density calculation formula. The specific calculation formula is:

[0186]

[0187] Where ρ1 is the gray density influence index, W f W is the weight of the filter paper containing the dirt after drying, in grams; i is the initial weight of the filter paper after drying, and A is the contaminated area on the insulator surface.

[0188] The salt density impact index can be obtained according to the preset salt density calculation formula. The specific calculation formula is:

[0189]

[0190] Where ρ2 is the salt density influence index, S a is the salt content, V is the volume of distilled water, and A is the contaminated area on the insulator surface.

[0191] Exemplarily, the embodiment of the present application performs flashover tests on 1100 kV composite insulators with arbitrary ash density and salt density. The test results are shown in the following table, with a total of 10 groups of valid data:

[0192] <![CDATA[ρ1(mg / cm 2 )]]> <![CDATA[ρ2(mg / cm 2 )]]> <![CDATA[U f / kV]]> <![CDATA[ρ1(mg / cm 2 )]]> <![CDATA[ρ2(mg / cm 2 )]]> <![CDATA[U f / kV]]> 0.55 0.09 1542.8 1.62 0.21 1208.8 0.62 0.32 1322.1 2.32 0.46 1083.8 1.80 0.08 1329.7 3.89 0.29 1032.0 1.59 0.11 1295.0 3.11 0.48 1020.0 1.41 0.23 1250.7 4.49 0.32 1005.0

[0193] Table 3

[0194] Among them, U f is the flashover voltage value.

[0195] Assume U f Satisfies the functional relationship with ρ1 and ρ2 The least square method was used to fit the above test results and obtain U f The relationship between ρ1 and ρ2 is Here, the average value of ρ1 and ρ2 is used as the reference value for calculation, and the final pollution flashover voltage of the insulator to be tested is 1141.103.kV. O is the reference voltage level, which is set to 1100 kV in the embodiment of the present application.

[0196] In some embodiments, the optimal air clearance acquisition module 201 further includes:

[0197] In the embodiment of the present application, it is first assumed that the initial value of the first influencing factor m and the second influencing factor w is 0, the threshold room temperature is 25° C., the poster height is 0, and the threshold room relative humidity is 60%, and the initial value of the atmospheric correction coefficient is calculated.

[0198] Then calculate the 50% impulse discharge voltage withstand voltage of the air gap as the lightning impulse insulation level and the switching impulse insulation level to clarify the lightning arrester configuration and insulation level of the offshore converter station.

[0199] According to the preset air clearance-voltage relationship formula (which can be an empirical formula), the air clearance for lightning overvoltage and switching overvoltage can be obtained, as follows:

[0200]

[0201]

[0202] Where d1 is the air clearance of lightning overvoltage, U 50-thun is the lightning overvoltage under standard atmospheric conditions, K is the electrode shape coefficient, different coefficients represent different electrode shapes, and the larger the shape, the more uniform the electric field. Since the influence of the motor shape is not considered in the embodiment of the present application, K is fixed to 1, so that a larger air clearance can be obtained to ensure a larger safety margin; d2 is the air clearance of the operating overvoltage, U 50-op It is the operating overvoltage under standard atmospheric conditions.

[0203] In the embodiment of the present application, the operation impulse insulation level of the Y / D valve side of the low-potential converter transformer is calculated to be 1105 kV. In general, in order to ensure safe operation, the larger air clearance between the lightning impulse and the operation impulse calculation value is taken as the minimum safe air clearance of the point. Due to the saturation effect of the gap under the operation impulse, the air clearance required under the operation voltage in the valve hall is much larger than the air clearance determined by the lightning impulse, so the air clearance of the operation overvoltage is generally taken.

[0204] In order to improve the calculation accuracy, the embodiment of the present application needs to iteratively calculate the air clearance of lightning overvoltage and switching overvoltage through an iterative factor, so as to obtain an air clearance value that is more in line with the actual situation, and effectively reduce the air clearance of the offshore platform converter station and the overall platform volume.

[0205] Specifically, assuming that the initial values ​​of the first influencing factor m and the second influencing factor w are 0, the threshold room temperature is 25°C, the poster height is 0, and the threshold room relative humidity is 60%, the initial value of the atmospheric correction coefficient is calculated as follows:

[0206]

[0207]

[0208] k = 1 + 0.01 (h / g-11) = 2.267;

[0209]

[0210] Wherein, h is absolute humidity, R is relative humidity, which is 60% here. Since the first and second influencing factors are both defined as 0, the iteration factor g is 0.1, and k1 and k2 are both 1.

[0211] Then the lightning overvoltage and switching overvoltage of the first iteration and the corresponding air clearance results are calculated. If the difference between the air clearance results calculated in two consecutive iterations is not less than the second threshold, the iteration continues and the air clearance result calculated the most recently is substituted into A new iteration factor g is calculated, and then updated k1 and k2 are obtained according to Table 2 provided in the embodiment of the present application, and the atmospheric correction coefficient is further updated for the next iterative calculation until the iteration stops.

[0212] As mentioned above, in order to ensure the safe operation of the system as much as possible, the air clearance of the operating overvoltage is generally taken. Therefore, after the minimum air clearance of the operating overvoltage is obtained, the minimum air clearance of the flashover voltage is calculated according to the preset air clearance-voltage relationship formula, and the minimum air clearance of the two is compared, and the maximum value is selected as the optimal air clearance.

[0213] Implementing the embodiments of the present application has the following beneficial effects:

[0214] The embodiment of the present application first collects weather and meteorological data related to the temperature, humidity, salinity and grayscale of the offshore converter platform, and then calculates the lightning overvoltage and the operating overvoltage based on the weather and meteorological data, fully considering the influence of the meteorological environment; then, a pollution test is performed on the insulator to obtain the pollution flashover voltage related to the grayscale and salinity, and the air clearance under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage are calculated respectively, and the maximum air clearance is selected as the data basis for designing the layout of the valve hall electrical equipment of the offshore converter platform, so as to comprehensively consider the air clearance under different voltages, more comprehensively meet the safety requirements of the offshore converter platform under different operating conditions, and reduce the total construction cost by effectively reducing the overall volume of the offshore converter station while ensuring the safety of the converter platform.

[0215] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for calculating the air clearance of an offshore converter platform, characterized in that: include: Calculate the lightning overvoltage and operating overvoltage at the test point through the weather and meteorological data collected from the offshore converter platform; Under the preset artificial pollution test conditions, measure the pollution flashover voltage of the insulator to be tested; According to a preset empirical formula, iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the switching overvoltage, respectively, and select the maximum value from the minimum air clearances as the optimal air clearance; Based on the optimal air clearance, the layout of the valve hall electrical equipment of the offshore converter platform is designed.

2. The air clearance calculation method of the offshore converter platform according to claim 1, characterized in that: The weather and meteorological data of the offshore converter platform are collected to calculate the lightning overvoltage and operating overvoltage of the test point, specifically: Acquiring weather and meteorological data of the offshore converter platform, and calculating the critical impulse flashover voltage of the air gap in the actual atmospheric environment according to the weather and meteorological data; According to the preset first ratio and the critical impulse flashover voltage, the lightning overvoltage in the actual atmospheric environment is obtained; According to the preset second ratio and the critical impulse flashover voltage, the operating overvoltage in the actual atmospheric environment is obtained; The lightning overvoltage and the operating overvoltage are processed by using a g parameter method to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions.

3. The air clearance calculation method of the offshore converter platform according to claim 2 is characterized in that: The g parameter method is used to process the lightning overvoltage and the operating overvoltage to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions, specifically: According to the weather and meteorological data, humidity data and temperature data are obtained; Based on the g parameter method, a humidity correction coefficient is set according to the humidity data, and a temperature correction coefficient is set according to the temperature data; Determine the atmospheric correction factor based on the humidity correction factor and the temperature correction factor; The lightning overvoltage and the operating overvoltage are processed respectively by the atmospheric correction coefficient to obtain the lightning overvoltage and the operating overvoltage under standard atmospheric conditions.

4. The air clearance calculation method of the offshore converter platform according to claim 3 is characterized in that: The lightning overvoltage and the operating overvoltage are specifically: The specific expression of the lightning overvoltage is: Where U 50-thun is the lightning overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-thum Lightning impulse insulation level of electrical equipment on offshore converter platforms, K q is the atmospheric correction factor; The specific expression of the operating overvoltage is: Where U 50-op is the operating overvoltage under standard atmospheric conditions, K ω is the margin factor, U ω-op Operation impulse insulation level for electrical equipment of offshore converter platforms, K q is the atmospheric correction factor.

5. The air clearance calculation method of the offshore converter platform according to claim 1, characterized in that: The method of measuring the pollution flashover voltage of the insulator to be tested under the preset artificial pollution test conditions is as follows: Based on the artificial pollution test conditions, a preset uniform voltage boost method is used to perform several voltage boost flashover tests on the insulator to be tested, and a flashover voltage value of each voltage boost flashover test is obtained; After each voltage-up flashover test, the insulator to be tested is processed, and the ash density influence index and salt density influence index of each voltage-up flashover test are obtained respectively by using the preset ash density calculation formula and salt density calculation formula; The flashover voltage value, ash density influence index and salt density influence index are fitted and analyzed by the least square method to obtain the pollution flashover voltage of the insulator to be tested.

6. The air clearance calculation method of the offshore converter platform according to claim 5, characterized in that: The flashover voltage value obtained in each voltage-boosting flashover test is specifically: Record the experimental data of each voltage-boosting flashover test; A first threshold number of lowest values ​​are selected from the experimental data, and an average value of the lowest values ​​is used as the flashover voltage value.

7. The air clearance calculation method of the offshore converter platform according to claim 1, characterized in that: According to the preset empirical formula, the minimum air clearance under the pollution flashover voltage, the lightning overvoltage and the switching overvoltage are iteratively calculated respectively, and the maximum value is selected from the minimum air clearance as the optimal air clearance, specifically: Calculate the pollution flashover voltage according to a preset air clearance-voltage relationship formula to obtain a first minimum air clearance under the pollution flashover voltage; According to a preset air clearance-voltage relationship formula, by iterating the iteration factor, the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the switching overvoltage are calculated; A maximum value is selected from the first minimum air clearance, the second minimum air clearance and the third minimum air clearance as the optimal air clearance.

8. The air clearance calculation method of the offshore converter platform according to claim 7, characterized in that: The second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the switching overvoltage are calculated by iterating the iteration factor according to the preset air clearance-voltage relationship formula, specifically: According to a preset air clearance-voltage relationship formula and an iteration factor, the lightning overvoltage and the switching overvoltage are iteratively calculated, and a corresponding air clearance result is obtained in each iterative calculation; After each iterative calculation is completed, the iteration factor is updated according to the air clearance result obtained this time and the preset iterative update formula, and the updated iteration factor is used in the next iterative calculation; When the difference between the air clearance results obtained by two adjacent iterative calculations is less than a second threshold, the iterative calculation is stopped, and the second minimum air clearance under the lightning overvoltage and the third minimum air clearance under the operating overvoltage are determined.

9. The air clearance calculation method of the offshore converter platform according to claim 8, characterized in that: The iterative update formula is specifically: In the formula, g is the iteration factor, U 50 is the lightning overvoltage or the operating overvoltage, d is the air clearance result, δ is the air relative density, and k is the proportional factor.

10. An air clearance calculation system for an offshore converter platform, characterized in that: include: Impulse test voltage acquisition module, pollution flashover voltage acquisition module, optimal air clearance acquisition module and valve hall layout design module; The impulse test voltage acquisition module is used to calculate the lightning overvoltage and operating overvoltage of the test point through the collected weather and meteorological data of the offshore converter platform; The pollution flashover voltage acquisition module is used to measure the pollution flashover voltage of the insulator to be tested under preset artificial pollution test conditions; The optimal air clearance acquisition module is used to iteratively calculate the minimum air clearances under the pollution flashover voltage, the lightning overvoltage and the operating overvoltage according to a preset empirical formula, and select the maximum value from the minimum air clearances as the optimal air clearance; The valve hall layout design module is used to design the layout of the valve hall electrical equipment of the offshore converter platform according to the optimal air clearance.

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