Method and device for selecting minimum air clearance of end fittings of wall bushings in converter stations

Abstract

The present application discloses a method and device for selecting the minimum air clearance of the end fitting of a wall-piercing bushing in a converter station. The method includes: calculating the minimum corona inception field strength on the surface of the end fitting according to the structural parameters of the end fitting; after setting the distance from the lowest point of the end fitting to the ground, constructing a simulation model and calculating the electric field strength through finite element simulation software, so as to obtain the minimum discharge voltage capable of generating the corona inception field strength at the distance from the lowest point of the end fitting to the ground; adjusting the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtaining several minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground; calculating the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground, and finding the minimum air clearance of the end fitting from the ground from the relationship curve according to the switching impulse discharge voltage. The present application realizes improving the safety of power equipment and reducing electrical risks.

Description

Technical Field

[0001] The present application relates to the technical field of fittings, and in particular, to a method and device for selecting the minimum air clearance of the end fitting of a wall-through bushing in a converter station. Background Art

[0002] A converter station is a hub to ensure the smooth progress of UHV power transmission. The shielding of the valve hall fittings not only determines the operation reliability of related equipment, but also directly affects the net space size of the entire valve hall. As a typical valve hall fitting, the wall-through bushing is large in size, and the air gap formed by it and the surrounding grounding bodies is closer to a slightly non-uniform electric field. Compared with the previous rod-plate, rod-rod, and line tower head gaps, the corona starting area on the electrode surface is larger and the discharge starting position is more random. Moreover, the discharge characteristics of the bushing under switching impulse voltage are an important basis for selecting the insulation clearance of the valve hall. However, there is currently a lack of sufficient data support and corresponding engineering guidance for the installation of bushings and the selection of insulation clearances. Only some simple installation methods of wall-through bushings for optimizing space occupation can be realized, and their electrostatic shielding performance is not high, and the safety level needs to be improved. Summary of the Invention

[0003] The present application provides a method and device for selecting the minimum air clearance of the end fitting of a wall-through bushing in a converter station, which are used to improve the safety of power equipment and reduce electrical risks.

[0004] In view of this, the first aspect of the present application provides a method for selecting the minimum air clearance of the end fitting of a wall-through bushing in a converter station, including:

[0005] S1. Calculate the minimum corona starting field strength on the surface of the end fitting according to the structural parameters of the end fitting of the wall-through bushing in the converter station valve hall;

[0006] S2. After setting the distance from the lowest point of the end fitting to the ground, construct a simulation model of the wall-through bushing in the converter station valve hall and its surrounding environment through finite element simulation software and calculate the electric field strength, and obtain the minimum discharge voltage that can generate the corona starting field strength at the distance from the lowest point of the end fitting to the ground according to the calculated electric field strength distribution and the minimum corona starting field strength;

[0007] S3. Adjust the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtain several minimum discharge voltages, and generate a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground;

[0008] S4. Calculate the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground, and find the corresponding distance from the lowest point of the end fitting to the ground from the relationship curve according to the switching impulse discharge voltage to obtain the minimum air clearance from the end fitting to the ground.

[0009] Preferably, calculating the minimum corona inception field strength on the surface of the end fitting of the wall-piercing bushing in the valve hall of the converter station includes:

[0010] Calculating the minimum corona inception field strength on the surface of the end fitting of the wall-piercing bushing in the valve hall of the converter station according to the pipe diameter, outer diameter of the end fitting of the wall-piercing bushing in the valve hall of the converter station, and the voltage applied to the end fitting.

[0011] Preferably, obtaining the minimum discharge voltage capable of generating the corona inception field strength at the lowest point of the end fitting from the ground based on the calculated electric field strength distribution and the minimum corona inception field strength includes:

[0012] Calculating the electric field strength deviation according to the difference between each electric field strength in the calculated electric field strength distribution and the minimum corona inception field strength;

[0013] Obtaining the applied voltage corresponding to the electric field strength deviation within the preset range, and determining the minimum discharge voltage capable of generating the corona inception field strength at the lowest point of the end fitting from the ground according to the applied voltage.

[0014] Preferably, the calculation formula for the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground is:

[0015]

[0016] In the formula, U chmax is the maximum overvoltage that the minimum air clearance d min can withstand under standard atmospheric pressure conditions; U 50 is the switching impulse discharge voltage; k de is the design margin of the end fitting; σ is the coefficient of variation of the switching impulse discharge voltage; k at is the atmospheric correction coefficient.

[0017] Preferably, performing a preset number of position adjustments on the lowest point of the end fitting in the simulation model, obtaining a number of minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground includes:

[0018] S31. Keeping the distance from the lowest point of the end fitting to the wall in the simulation model, changing the distance from the lowest point of the end fitting to the ground a preset number of times, and returning to step S2 after each change in the distance from the lowest point of the end fitting to the ground, to obtain the minimum discharge voltages capable of generating the corona inception field strength at a preset number of distances from the lowest point of the end fitting to the ground under the same distance from the lowest point of the end fitting to the wall;

[0019] S32. Make a preset number of changes to the distance from the lowest point of the end fitting to the wall in the simulation model, and after each change to the distance from the lowest point of the end fitting to the wall, return to step S2 to obtain the minimum discharge voltage capable of generating a corona inception field strength at each of the preset number of distances from the lowest point of the end fitting to the wall and at each distance from the lowest point of the end fitting to the ground;

[0020] S33. Generate a relationship curve between the minimum discharge voltage and the corresponding distance from the lowest point of the end fitting to the ground for each distance from the lowest point of the end fitting to the wall.

[0021] Preferably, calculating the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground, and finding the corresponding distance from the lowest point of the end fitting to the ground from the relationship curve according to the switching impulse discharge voltage to obtain the minimum air clearance from the end fitting to the ground, includes:

[0022] Calculating the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground at several different distances from the lowest point of the end fitting to the wall;

[0023] Finding the corresponding distance from the lowest point of the end fitting to the ground from the corresponding relationship curve according to the switching impulse discharge voltage at each distance from the lowest point of the end fitting to the wall to obtain the minimum air clearance from the lowest point of the end fitting to the ground at different distances from the end fitting to the wall.

[0024] The second aspect of the present application provides a device for selecting the minimum air clearance of the end fitting of a converter station wall bushing, including:

[0025] A first calculation unit for calculating the minimum corona inception field strength on the surface of the end fitting according to the structural parameters of the end fitting of the converter station valve hall wall bushing;

[0026] A simulation unit for setting the distance from the lowest point of the end fitting to the ground in the finite element simulation software, constructing a simulation model of the converter station valve hall wall bushing and its surrounding environment through the finite element simulation software and calculating the electric field strength, and obtaining the minimum discharge voltage capable of generating a corona inception field strength at the distance from the lowest point of the end fitting to the ground according to the calculated electric field strength distribution and the minimum corona inception field strength;

[0027] A generation unit for making a preset number of position adjustments to the lowest point of the end fitting in the simulation model, obtaining a number of minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground;

[0028] A second calculation unit for calculating the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground, and finding the corresponding distance from the lowest point of the end fitting to the ground from the relationship curve to obtain the minimum air clearance from the end fitting to the ground.

[0029] Preferably, the first calculation unit is specifically configured to calculate the minimum corona inception field strength on the surface of the end fitting according to the pipe diameter, outer diameter of the end fitting of the wall-piercing bushing in the converter station valve hall, and the voltage applied to the end fitting.

[0030] Preferably, the simulation unit is specifically configured to:

[0031] Set the distance from the lowest point of the end fitting to the ground in the finite element simulation software, and construct a simulation model and calculate the electric field strength of the wall-piercing bushing in the converter station valve hall and its surrounding environment through the finite element simulation software;

[0032] Calculate the electric field strength deviation according to the difference between each electric field strength in the calculated electric field strength distribution and the minimum corona inception field strength;

[0033] Obtain the applied voltage corresponding to the electric field strength deviation within the preset range, and determine the minimum discharge voltage capable of generating the corona inception field strength at the distance from the lowest point of the end fitting to the ground according to the applied voltage.

[0034] Preferably, the calculation formula for the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground is:

[0035]

[0036] In the formula, U chmax is the maximum overvoltage that the minimum air clearance d min can withstand under standard atmospheric pressure conditions; U 50 is the switching impulse discharge voltage; k de is the design margin of the end fitting; σ is the coefficient of variation of the switching impulse discharge voltage; k at is the atmospheric correction coefficient.

[0037] It can be seen from the above technical solutions that the present application has the following advantages:

[0038] This application calculates the minimum corona inception field strength on the surface of the end fitting, and establishes a simulation model of the wall-penetrating bushing and its environment in a finite element simulation software. Then, it calculates the electric field distribution, and obtains a corresponding relationship curve by using data such as the simulation results and the distance from the lowest point of the end fitting to the ground. Finally, it determines the minimum air clearance from the end fitting of the bushing to the ground in combination with the calculated switching impulse discharge voltage, optimizing the electric field performance and reducing the non-uniform distribution of the electric field strength, thereby improving the stability and reliability of the equipment; moreover, by simulating with the simulation model to obtain the minimum air clearance, it can reduce the maintenance cost by reducing the damage that may be caused by electric field problems, reduce the cost, and at the same time improve the engineering efficiency, helping engineers make decisions more quickly and reducing the trial-and-error cost; in addition, it improves the reliability of the equipment, reduces the potential risk of equipment failure, extends the equipment life, helps improve the safety of power equipment, reduces the electrical risk, and improves the safety of the equipment and personnel. Brief Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0040] Figure 1 It is a schematic flowchart of a method for selecting the minimum air clearance of the end fitting of a wall-penetrating bushing in a converter station provided by an embodiment of the present application;

[0041] Figure 2 It is a simulation model diagram of the end fitting provided by an embodiment of the present application;

[0042] Figure 3 It is a simulation result diagram of the end fitting provided by an embodiment of the present application;

[0043] Figure 4 It is a relationship curve diagram between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground provided by an embodiment of the present application;

[0044] Figure 5 It is an installation diagram of the bushing after determining the minimum air clearance from the end fitting to the ground provided by an embodiment of the present application;

[0045] Figure 6 It is a schematic structural diagram of a device for selecting the minimum air clearance of the end fitting of a wall-penetrating bushing in a converter station provided by an embodiment of the present application. Detailed Description of the Embodiments

[0046] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0047] For ease of understanding, please refer to Figure 1 , an embodiment of this application provides a method for selecting the minimum air clearance of the end fitting of the wall-piercing bushing in a converter station, including:

[0048] S1. Calculate the minimum corona inception field strength on the surface of the end fitting according to the structural parameters of the end fitting of the wall-piercing bushing in the converter station valve hall.

[0049] The minimum corona inception field strength on the surface of the end fitting can be calculated based on the pipe diameter, outer diameter of the end fitting of the wall-piercing bushing in the converter station valve hall and the voltage applied to the end fitting. Specifically, for the wall-piercing bushing in the valve hall, the end fitting refers to the grading ring, and the main dimensional parameters of the grading ring are the outer diameter of its circular ring structure and the pipe diameter of its cross-section. After obtaining such data according to the drawings or design requirements, the following corona inception field strength formula can be used to calculate the corona inception field strength:

[0050]

[0051] In the above formula, U is the voltage applied to the grading ring, with the unit of kV / m; d is the pipe diameter of the grading ring, and D is the outer diameter of the grading ring, both with the unit of m; ε0 is the dielectric constant of air, generally taken as 1; E c is the corona inception field strength corresponding to the voltage applied to the grading ring. The minimum corona inception field strength on the surface of the end fitting can be calculated through the above formula.

[0052] By using the corona inception field strength formula to calculate the minimum corona inception field strength on the surface of the end fitting, only the structural data of the end fitting is used, without using the structural and physical property data of other structures of the bushing, and at the same time, environmental data such as air pressure is not used, greatly reducing the data requirements and improving the overall efficiency of the process.

[0053] S2. Set the distance from the lowest point of the end fitting to the ground in the finite element simulation software, construct a simulation model of the wall-piercing bushing in the converter station valve hall and its surrounding environment through the finite element simulation software, calculate the electric field strength, and obtain the minimum discharge voltage that can generate the corona inception field strength at the distance from the lowest point of the end fitting to the ground according to the calculated electric field strength distribution and the minimum corona inception field strength.

[0054] After setting the minimum distance from the lowest point of the end fitting to the ground, the geometric modeling and mesh generation of the bushing, wall, and air domain can be completed in the finite element simulation software COMSOL. After applying materials, the voltage value, voltage application position, and boundary conditions are set. Since the bushing is on the DC side of the valve hall, DC voltage should be applied, and the specific value is determined according to actual operating conditions and requirements. Since the grading ring is an electrostatic shielding structure, the final voltage application positions are the metal rod inside the bushing and the grading ring in the valve hall itself. For the boundary conditions, only the voltage of the outer boundary of the air domain needs to be set to 0. The obtained simulation model can refer to Figure 2 , and the simulation results can refer to Figure 3 .

[0055] Then, use the calculation function inside the finite element simulation software to complete the calculation of the electric field strength, and obtain the electric field distribution and maximum field strength data. Calculate the electric field strength deviation based on the difference between each electric field strength in the calculated electric field strength distribution and the minimum corona onset field strength; obtain the applied voltage corresponding to the electric field strength deviation within the preset range, and determine the minimum discharge voltage that can generate the corona onset field strength at the minimum distance from the lowest point of the end fitting to the ground according to the applied voltage.

[0056] In the embodiment of the present application, the lowest point of the end fitting should be the lowest point of the grading ring of the bushing inside the valve hall. By continuously and finely adjusting the voltage until the calculated field strength E satisfies the following relationship:

[0057]

[0058] In the above formula, a is the electric field strength deviation, and 5% is an empirical value. When the electric field strength deviation a reaches the preset range [-5%, +5%], record the specific voltage values applied to the grading ring and the rod at this time, and the average value of the voltages applied to the grading ring and the rod can be taken as the minimum discharge voltage that can generate the corona onset field strength at the specified distance from the lowest point of the end fitting to the ground.

[0059] In the embodiment of the present application, by using the finite element simulation software COMSOL for model establishment, mesh generation, and electric field strength calculation, the electric field strength distribution data can be obtained efficiently, and the influence of the bushing installation on the electric field can be understood more accurately.

[0060] S3. Adjust the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtain several minimum discharge voltages, and generate a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground.

[0061] Adjust the position layout of the simulation model, and repeat the electric field strength calculation and voltage data acquisition in step two. After obtaining a sufficient amount of minimum discharge voltage data, make a relationship curve between the minimum discharge voltage and the specified distance from the lowest point of the end fitting to the ground. Specifically:

[0062] S31. In the simulation model, keep the distance from the lowest point of the end fitting to the wall, change the distance from the lowest point of the end fitting to the ground for a preset number of times, and return to step S2 after each change of the distance from the lowest point of the end fitting to the ground, so as to obtain the minimum discharge voltage that can generate the corona inception field strength at a preset number of distances from the lowest point of the end fitting to the ground under the same distance from the lowest point of the end fitting to the wall;

[0063] During the adjustment, the structure of the bushing remains unchanged. Instead, by changing the inclination angle of the bushing itself, the distance from the lowest point of the grading ring to the ground is changed without changing the distance from the lowest point of the grading ring to the wall. When changing the lowest point of the grading ring, attention should be paid to adjusting the position and size of the established valve hall wall and air domain to ensure that the valve hall wall and the fixed installation fitting position of the bushing are in a joined state, and the overall bushing and wall model should be wrapped in the established air domain. The distance from the lowest point of the grading ring to the ground can be changed in a gradient of 0.5 m each time. At each gradient, perform the same simulation calculation as in step S2 to obtain the minimum discharge voltage at this gradient. Perform simulation calculations for multiple gradients to obtain at least 15 groups of minimum discharge voltage data at different gradients. Taking the distance from the lowest point of the grading ring to the ground as the horizontal axis and the minimum discharge voltage as the vertical axis, make a relationship curve graph as Figure 4 shown.

[0064] S32. Change the distance from the lowest point of the end fitting to the wall for a preset number of times in the simulation model, and return to step S2 after each change of the distance from the lowest point of the end fitting to the wall, so as to obtain the minimum discharge voltage that can generate the corona inception field strength at each distance from the lowest point of the end fitting to the ground under a preset number of distances from the lowest point of the end fitting to the wall;

[0065] After completing step S31, if directly executing step S4, only the minimum air clearance under the specified distance from the lowest point of the grading ring to the wall can be obtained. However, the requirements for valve hall construction are different, and the position of the grading ring, that is, its distances to the wall and the ground, are also different. In the project, different simulation data should be obtained according to different distances to the wall to meet the engineering design requirements. Therefore, then determine at which distances from the lowest point of the grading ring to the wall the minimum air clearance needs to be obtained according to the actual reference needs in the project, change the distance from the lowest point of the grading ring to the wall by adjusting the inclination angle when installing the bushing (at this time, do not consider the distance from the lowest point of the grading ring to the ground), and after the adjustment is completed, return to step S2, execute step S2 and step S31 to obtain the minimum discharge voltage that can generate the corona inception field strength at each distance from the lowest point of the end fitting to the ground under different distances from the lowest point of the end fitting to the wall.

[0066] S33. Generate a relationship curve between the minimum discharge voltage and the corresponding distance from the lowest point of the end fitting to the ground for each distance from the lowest point of the end fitting to the wall.

[0067] Assume there are a total of N different distances from the lowest point of the end fitting to the wall. For each distance from the lowest point of the end fitting to the wall, there are M sets of minimum discharge voltages that can generate the onset field strength at different distances from the lowest point of the end fitting to the ground. For the N different distances from the lowest point of the end fitting to the wall, relationship curves are plotted for the corresponding M sets of data. When plotting, the distance from the lowest point of the end fitting to the ground is taken as the horizontal axis, and the minimum discharge voltage is taken as the vertical axis. Through non-linear fitting, a relationship curve graph as shown in Figure 4 is obtained. Finally, N relationship curve graphs can be obtained, and each relationship curve graph corresponds to a distance from the lowest point of the end fitting to the wall.

[0068] In the embodiment of the present application, relationship curves between different specified distances to the ground and the minimum voltages that can generate the onset field strength are obtained using different simulation data. This provides an intuitive and clear way to represent the correlation between the two and establishes a convenient data index.

[0069] S4. Calculate the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground. According to the switching impulse discharge voltage, find the corresponding distance from the lowest point of the end fitting to the ground in the relationship curve to obtain the minimum air clearance from the end fitting to the ground.

[0070] If the minimum air clearance of the lowest point of the grading ring in the valve hall is known, substituting it into the following formula can calculate the maximum overvoltage that the air clearance can withstand under standard atmospheric pressure conditions:

[0071]

[0072] In the formula, d min is the minimum air clearance, with the unit of m; U chmax is the maximum overvoltage that the minimum air clearance can withstand under standard atmospheric pressure conditions, with the unit of kV; g is the gap coefficient representing the electrode shape characteristics, and generally takes 1.2 for the grading ring - to - ground gap.

[0073] After calculating the maximum overvoltage, use the correlation formula between the withstand voltage and the 50% switching impulse voltage, that is, the following formula to calculate the switching impulse discharge voltage corresponding to the minimum air clearance:

[0074]

[0075] In the formula, U 50 is the switching impulse discharge voltage, with the unit of kV; k de is the design margin of the end fitting, generally taking 1.05; σ is the coefficient of variation of the switching impulse discharge voltage, generally taking 6% for the switching impulse voltage; k at is the atmospheric correction coefficient. For the atmospheric correction coefficient, different settings should be made for different situations, and kat It is calculated by the following formula:

[0076]

[0077] In the formula, k α is the air density correction coefficient; k β is the humidity correction coefficient; δ is the relative air density, generally taken as 1; f1 and f2 are intermediate parameters, and the specific values should be determined according to the calculated value of the parameter η:

[0078]

[0079] After calculating the parameter η, the specific values of f1 and f2 are obtained by referring to the following formula:

[0080]

[0081]

[0082] In the embodiment of the present application, the 50% operating impulse voltage formula for the end fitting is used to calculate the operating impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground at the specified valve hall voltage level, ensuring a high fitting degree between the calculated data and the measured data in the actual engineering test and improving the accuracy of the data.

[0083] After calculating the operating impulse discharge voltages corresponding to the minimum air clearances from the lowest points of several different end fittings to the wall to the ground, the operating impulse discharge voltages at the lowest points of each end fitting to the wall correspond to the ordinates of the relationship curves obtained in step S3 at the lowest points of each end fitting to the wall. Use data analysis software such as matlab or origin to find its corresponding abscissa. The value of this abscissa is the minimum air clearance of the actual grading ring lowest point of the operating impulse discharge voltage at the lowest points of each end fitting to the wall, so as to obtain the minimum air clearances from the lowest points of the end fittings to the ground at different distances from the wall. Finally, according to the minimum air clearances from the lowest points of the end fittings to the ground at different distances from the wall applied to the actual valve hall construction, reference can be made to Figure 5 .

[0084] This application calculates the minimum corona inception field strength on the surface of the end fitting, establishes a simulation model of the wall bushing and its environment in a finite element simulation software, then calculates the electric field distribution, and obtains a corresponding relationship curve using data such as the simulation results and the distance from the lowest point of the end fitting to the ground. Finally, the minimum air clearance between the end fitting of the bushing and the ground is determined by combining the calculated switching impulse discharge voltage, optimizing the electric field performance, reducing the non-uniform distribution of the electric field strength, thereby improving the stability and reliability of the equipment; moreover, by simulating the minimum air clearance through the simulation model, the maintenance cost can be reduced by reducing the damage that may be caused by electric field problems, the cost is lowered, and at the same time, the engineering efficiency is improved, helping engineers make decisions more quickly and reducing the cost of trial and error; in addition, the reliability of the equipment is improved, the potential risk of equipment failure is reduced, the equipment life is extended, which helps to improve the safety of power equipment, reduce electrical risks, and improve the safety of equipment and personnel.

[0085] The above is an embodiment of a method for selecting the minimum air clearance of the end fitting of the wall bushing in a converter station provided by this application. The following is an embodiment of a device for selecting the minimum air clearance of the end fitting of the wall bushing in a converter station provided by this application.

[0086] Please refer to Figure 6 , a device for selecting the minimum air clearance of the end fitting of the wall bushing in a converter station provided by an embodiment of this application, includes:

[0087] A first calculation unit for calculating the minimum corona inception field strength on the surface of the end fitting according to the structural parameters of the end fitting of the wall bushing in the valve hall of the converter station;

[0088] A simulation unit for setting the distance from the lowest point of the end fitting to the ground in the finite element simulation software, constructing a simulation model and calculating the electric field strength of the wall bushing in the valve hall of the converter station and its surrounding environment through the finite element simulation software, and obtaining the minimum discharge voltage that can generate the corona inception field strength at the distance from the lowest point of the end fitting to the ground according to the calculated electric field strength distribution and the minimum corona inception field strength;

[0089] A generation unit for adjusting the position of the lowest point of the end fitting in the simulation model a preset number of times, obtaining several minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance from the lowest point of the end fitting to the ground;

[0090] A second calculation unit for calculating the switching impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground, and finding the corresponding distance from the lowest point of the end fitting to the ground from the relationship curve according to the switching impulse discharge voltage to obtain the minimum air clearance between the end fitting and the ground.

[0091] As a further improvement, the first calculation unit is specifically configured to calculate the minimum corona inception field strength on the surface of the end fitting according to the pipe diameter, outer diameter of the end fitting of the wall-piercing bushing in the valve hall of the converter station, and the voltage applied to the end fitting.

[0092] As a further improvement, the simulation unit is specifically configured to:

[0093] Set the distance from the lowest point of the end fitting to the ground in the finite element simulation software, and construct a simulation model and calculate the electric field strength of the wall-piercing bushing in the valve hall of the converter station and its surrounding environment through the finite element simulation software;

[0094] Calculate the electric field strength deviation according to the difference between each electric field strength in the calculated electric field strength distribution and the minimum corona inception field strength;

[0095] Obtain the applied voltage corresponding to the electric field strength deviation within the preset range, and determine the minimum discharge voltage that can generate the corona inception field strength at the distance from the lowest point of the end fitting to the ground.

[0096] As a further improvement, the calculation formula for the switching impulse discharge voltage corresponding to the minimum air clearance from the lowest point of the end fitting to the ground is:

[0097]

[0098] In the formula, U chmax is the maximum overvoltage that the minimum air clearance d min can withstand under standard atmospheric pressure conditions; U 50 is the switching impulse discharge voltage; k de is the design margin of the end fitting; σ is the coefficient of variation of the switching impulse discharge voltage; k at is the atmospheric correction coefficient.

[0099] This application calculates the minimum corona inception field strength on the surface of the end fitting, establishes a simulation model of the wall-piercing bushing and its environment in the finite element simulation software, then calculates the electric field distribution, and obtains a corresponding relationship curve using data such as the simulation results and the distance from the lowest point of the end fitting to the ground. Finally, it determines the minimum air clearance between the end fitting of the bushing and the ground in combination with the calculated switching impulse discharge voltage, optimizing the electric field performance, reducing the uneven distribution of the electric field strength, thereby improving the stability and reliability of the equipment; moreover, by obtaining the minimum air clearance through simulation with the simulation model, it can reduce the maintenance cost by reducing the possible damage caused by electric field problems, lower the cost, and at the same time improve the engineering efficiency, helping engineers make decisions more quickly and reducing the trial-and-error cost; in addition, it improves the reliability of the equipment, reduces the potential equipment failure risk, extends the equipment life, helps improve the safety of power equipment, reduces electrical risks, and improves the safety of the equipment and personnel.

[0100] An embodiment of the present application further provides an electronic device, which includes a processor and a memory;

[0101] The memory is used to store program codes and transmit the program codes to the processor;

[0102] The processor is used to execute the method for selecting the minimum air clearance of the end fitting of the converter station wall bushing in the foregoing method embodiment according to the instructions in the program codes.

[0103] An embodiment of the present application further provides a computer-readable storage medium, which is used to store program codes. When the program codes are executed by a processor, the method for selecting the minimum air clearance of the end fitting of the converter station wall bushing in the foregoing method embodiment is implemented.

[0104] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0105] Terms such as "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0106] It should be understood that in the present application, "at least one (item)" means one or more, and "multiple" means two or more. "And / or" is used to describe the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B may be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one of the following (items)" or its similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, at least one of a, b, or c may mean: a, b, c, "a and b", "a and c", "b and c", or "a, b, and c", where a, b, and c may be single or multiple.

[0107] In several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0108] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0109] In addition, the functional units in each embodiment of this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0110] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of this application. The foregoing storage medium includes: USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks or optical disks and other media that can store program codes.

[0111] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for selecting the minimum air clearance of the end fittings of the wall bushing in a converter station, characterized in that: include: S1. Calculate the minimum corona initiation field strength on the surface of the end fittings of the wall bushing in the converter station valve hall according to the structural parameters of the end fittings; S2. After setting the distance between the lowest point of the end fitting and the ground, a simulation model is constructed and the electric field strength is calculated for the wall bushing of the converter station valve hall and its environment through finite element simulation software, and the minimum discharge voltage that can generate the corona initiation field strength under the distance between the lowest point of the end fitting and the ground is obtained according to the calculated electric field strength distribution and the minimum corona initiation field strength; Wherein, obtaining the minimum discharge voltage capable of generating the corona initiation field strength at the lowest point of the end fitting to the ground according to the calculated electric field strength distribution and the minimum corona initiation field strength comprises: Calculating the electric field intensity deviation according to the difference between each electric field intensity in the calculated electric field intensity distribution and the minimum corona initiation field intensity; Obtaining an applied voltage corresponding to an electric field strength deviation within a preset range, and determining a minimum discharge voltage capable of generating a corona initiation field strength at a distance between the lowest point of the end fitting and the ground according to the applied voltage; S3, adjusting the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtaining a number of minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance between the lowest point of the end fitting and the ground; S4. Calculate the operating impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground, and find the corresponding distance between the lowest point of the end fitting and the ground from the relationship curve according to the operating impulse discharge voltage to obtain the minimum air clearance between the end fitting and the ground.

2. The method for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 1 is characterized in that: The method of calculating the minimum corona initiation field strength on the surface of the end fitting of the wall bushing in the valve hall of the converter station according to the structural parameters of the end fitting comprises: The minimum corona initiation field strength on the surface of the end fitting is calculated based on the pipe diameter and outer diameter of the end fitting of the wall bushing in the converter station valve hall and the voltage applied to the end fitting.

3. The method for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 1 is characterized in that: The calculation formula for the switching impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground is: Where U chmax The minimum air clearance d under standard atmospheric pressure conditions min The maximum overvoltage that can be tolerated; U 50 k is the operating impulse discharge voltage; de is the design margin of the end fittings; σ is the coefficient of variation of the switching impulse discharge voltage; k at is the atmospheric correction factor.

4. The method for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 1, characterized in that: The step of adjusting the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtaining a plurality of minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance between the lowest point of the end fitting and the ground includes: S31, maintaining the distance between the lowest point of the end fitting and the wall in the simulation model, changing the distance between the lowest point of the end fitting and the ground for a preset number of times, and returning to step S2 after each change of the distance between the lowest point of the end fitting and the ground, and obtaining the minimum discharge voltage that can generate the corona initiation field strength under the same distance between the lowest point of the end fitting and the wall and the preset number of distances between the lowest point of the end fitting and the ground; S32, in the simulation model, changing the distance between the lowest point of the end fitting and the wall for a preset number of times, and returning to step S2 after each change of the distance between the lowest point of the end fitting and the wall, to obtain the minimum discharge voltage that can generate the corona initiation field strength under the preset number of distances between the lowest point of the end fitting and the wall and the distance between the lowest point of each end fitting and the ground; S33 generates a relationship curve between the minimum discharge voltage and the corresponding distance between the lowest point of each end fitting and the ground, based on the distance between the lowest point of each end fitting and the wall.

5. The method for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 4, characterized in that: The calculating the switching impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground, and finding the corresponding distance between the lowest point of the end fitting and the ground from the relationship curve according to the switching impulse discharge voltage to obtain the minimum air clearance between the end fitting and the ground, comprises: Calculate the switching impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground under several different distances between the lowest point of the end fitting and the wall; According to the operating impulse discharge voltage at the distance between the lowest point of each end fitting and the wall, the corresponding distance between the lowest point of the end fitting and the ground is found from the corresponding relationship curve to obtain the minimum air clearance between the lowest point of the end fitting and the ground at different distances between the lowest point of the end fitting and the wall.

6. A device for selecting the minimum air clearance of the end fittings of the wall bushing in a converter station, characterized in that: include: The first calculation unit is used to calculate the minimum corona induction field strength on the surface of the end fitting of the wall bushing of the converter station valve hall according to the structural parameters of the end fitting; A simulation unit is used to set the distance between the lowest point of the end fitting and the ground in the finite element simulation software, to construct a simulation model and calculate the electric field strength of the wall bushing of the converter station valve hall and its environment through the finite element simulation software, and to obtain the minimum discharge voltage that can generate the corona initiation field strength under the distance between the lowest point of the end fitting and the ground according to the calculated electric field strength distribution and the minimum corona initiation field strength; The simulation unit is specifically used to set the distance between the lowest point of the end fitting and the ground in the finite element simulation software, and to construct a simulation model and calculate the electric field strength of the wall bushing of the converter station valve hall and its environment through the finite element simulation software; Calculating the electric field intensity deviation according to the difference between each electric field intensity in the calculated electric field intensity distribution and the minimum corona initiation field intensity; Obtaining an applied voltage corresponding to an electric field strength deviation within a preset range, and determining a minimum discharge voltage capable of generating a corona initiation field strength at a distance between the lowest point of the end fitting and the ground according to the applied voltage; A generating unit, used for adjusting the position of the lowest point of the end fitting in the simulation model for a preset number of times, obtaining a plurality of minimum discharge voltages, and generating a relationship curve between the minimum discharge voltage and the distance between the lowest point of the end fitting and the ground; The second calculation unit is used to calculate the operating impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground, and find the corresponding distance between the lowest point of the end fitting and the ground from the relationship curve according to the operating impulse discharge voltage to obtain the minimum air clearance between the end fitting and the ground.

7. The device for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 6, characterized in that: The first calculation unit is specifically used to calculate the minimum corona induction field strength on the surface of the end fitting of the converter station valve hall wall bushing according to the pipe diameter, outer diameter and voltage applied to the end fitting.

8. The device for selecting the minimum air clearance of the end fittings of the wall bushing of a converter station according to claim 6, characterized in that: The calculation formula for the switching impulse discharge voltage corresponding to the minimum air clearance between the lowest point of the end fitting and the ground is: Where U chmax The minimum air clearance d under standard atmospheric pressure conditions min The maximum overvoltage that can be tolerated; U 50 k is the operating impulse discharge voltage; de is the design margin of the end fittings; σ is the coefficient of variation of the switching impulse discharge voltage; k at is the atmospheric correction factor.

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