An evaluation method for the insulation margin risk coefficient of a UHV GIL three-pillar insulator

Abstract

The present invention discloses a method for evaluating the insulation margin risk coefficient of a three-pillar insulator of UHV GIL. Parameters of epoxy resin / aluminum oxide composite materials are measured and obtained; a geometric model of the three-pillar insulator is established; control equations of the electric field and stress field are established; the electric field, stress field and energy equation are iteratively solved within the region of the geometric model of the three-pillar insulator; the breakdown shape parameters of the epoxy resin / aluminum oxide composite materials are calculated; the energy distribution is derived into MATLAB to calculate the risk assessment coefficient; the electric field distribution, stress distribution, energy distribution and breakdown channel of the three-pillar insulator are obtained. The present invention solves the problem of evaluating the insulation margin risk coefficient of the three-pillar insulator under electrical and mechanical loads.

Description

Technical Field

[0001] The present invention belongs to the field of computational electro-mechanics, and specifically relates to the technical field of gas-insulated transmission equipment. More specifically, it relates to a method for evaluating the insulation margin risk coefficient of a three-pillar insulator for ultra-high voltage GIL. Background Art

[0002] Gas-insulated transmission line (GIL) is a metal-encapsulated transmission equipment, which has been widely used in the power system due to its high reliability, strong environmental adaptability, no secondary pollution and other advantages. The three-pillar insulator widely used in GIL mainly plays the roles of insulation and support, and its insulation performance largely determines the safety and stability of GIL. However, in recent years, the three-pillar insulator has frequently suffered breakdown and explosion failures during operation, seriously threatening the safety of the entire transmission system. During operation, the three-pillar mainly bears strong electric fields and complex mechanical stresses. Under extreme electrical and mechanical loads, the three-pillar insulator is prone to insulation breakdown failures. Therefore, carrying out the evaluation of the insulation margin risk coefficient of the three-pillar insulator can enable the GIL operators to clearly recognize the operation risks of the insulator, which has important scientific significance and engineering application value. Summary of the Invention

[0003] To solve the above problems, the present invention proposes a method for evaluating the insulation margin risk coefficient of a three-pillar insulator for ultra-high voltage GIL, which can efficiently and accurately predict the insulation margin risk coefficient of the three-pillar insulator under electrical and mechanical loads.

[0004] The object of the present invention is achieved by the following technical solutions.

[0005] The method for evaluating the insulation margin risk coefficient of a three-pillar insulator for ultra-high voltage GIL of the present invention includes the following steps:

[0006] Step 1: Measure and obtain material parameters

[0007] Perform uniaxial tension and broadband dielectric spectroscopy tests on the three-pillar insulator with epoxy resin / aluminum oxide composite materials respectively to obtain the parameters of the epoxy resin / aluminum oxide composite materials, including: the elastic modulus of the epoxy resin / aluminum oxide composite material Y p , the Poisson's ratio of the epoxy resin / aluminum oxide composite material mu , the tensile strength of the epoxy resin / aluminum oxide composite material σ p , the relative dielectric constant of the epoxy resin / aluminum oxide composite material ε p ; conduct AC breakdown tests on epoxy resin / aluminum oxide composite material specimens with different thicknesses and obtain their breakdown field strengths E b .

[0008] Step 2: Establish the geometric model of the three-pillar insulator

[0009] Based on the COMOSL finite element software, establish the geometric model of the 1100 kV HVAC-GIL three-pillar insulator, and perform mesh division on the geometric model of the three-pillar insulator. Among them, the geometric model of the three-pillar insulator includes a high-voltage conductor, three-pillar insulators, and a housing embedded coaxially from the inside out. Metal inserts are provided between the three ends of the three-pillar insulator and the housing.

[0010] Step 3: Calculate the total energy of the three-pillar insulator

[0011] (1) Establish the electric field control equation

[0012] The electric field strength is solved according to the Poisson equation of the electrostatic field:

[0013]

[0014] In the formula, ε r is the relative permittivity of the three-pillar insulator material; E is the electric field strength, kV / mm; is the electric potential, kV.

[0015] Boundary conditions: The potential of the high-voltage conductor is set to 1100 kV, and the housing is grounded.

[0016] (2) Establish the stress field control equation

[0017] Assume that the three-pillar insulator material is a linear elastic material, and the stress distribution is solved according to Hooke's law:

[0018]

[0019] In the formula, σ is the normal stress, Pa; T is the shear stress, Pa; ν and are the elastic deformations under normal stress and shear stress respectively; Y is the elastic modulus of the three-pillar insulator material, Pa; G is the shear modulus of the three-pillar insulator material Pa.

[0020] Boundary conditions: The high-voltage conductor is subjected to gravity, and the metal insert is set as a fixed constraint.

[0021] (3) Calculate the total energy

[0022] Based on the above control equations, calculate the electric field and stress distributions, and calculate the total energy according to the following formula W :

[0023]

[0024] Among them, W ele is the electrostatic energy, Pa; W mec is the strain energy, Pa.

[0025] Assume that the three-pillar insulator is a linear dielectric with a dielectric constant, W ele which is given by the following formula:

[0026]

[0027] where ε 0 is the relative dielectric constant of vacuum.

[0028] The strain energy W mec depends on the maximum value of the normal strain energy W mec1 and the shear strain energy W mec2 and is expressed as:

[0029]

[0030] Step 4, calculate the shape parameter of the breakdown model

[0031] Breakdown is developed from internal defects. Assume that a defect occurs in any region of the dielectric. Under the action of the electro-force field, this defect will cause a breakdown channel to form in the dielectric. Therefore, the probability of dielectric breakdown can be calculated by the probability of defect generation in the dielectric. The probability of defect generation in a certain region of the dielectric follows the Weibull distribution:

[0032]

[0033] where W is the energy of this region; W c0 is the size d 0 of the critical breakdown energy; β is the shape parameter.

[0034] There is a dielectric with a thickness of d , which is divided into n layer regions between two electrodes. The length of each region is d 0. Then n = d / d 0. When one or more regions on any path between the two electrodes generate defects, breakdown will occur. Then the probability of breakdown of this dielectric is:

[0035]

[0036] where W i is the i total energy of the nth region.

[0037] For the flat specimen undergoing breakdown testing, with a uniform electric field inside it, the above equation can be simplified to:

[0038]

[0039] After equation transformation, the above equation can be derived as:

[0040]

[0041] The denominator of the exponent in the formula W c0 · n -1 / β can reflect the changing trend that the breakdown energy decreases with the increase of thickness, which conforms to the experimental law. Therefore, the critical breakdown energy d at a thickness of W c can be expressed as:

[0042]

[0043] According to the measured breakdown field strength E b of the epoxy resin / aluminum oxide composite and the relationship with the thickness d :

[0044]

[0045] The critical breakdown energy W c can be calculated based on the experimentally measured breakdown field strength E b as:

[0046]

[0047] where ε 0 is the vacuum permittivity, ε r is the relative permittivity of the dielectric material. Therefore, from the equality of formulas 12 and 14, we can obtain:

[0048]

[0049] According to the relationship between the breakdown field strength and thickness of epoxy resin / aluminum oxide, the β can be obtained using the fitting formula 13.

[0050] Step 5, calculate the risk assessment coefficient of the three-pillar insulator

[0051] (1) Export the total energy W Data

[0052] Calculate the total energy in COMSOL software W ( x , y , z , W i ), and then export the data. W Contains 4 columns of data, namely x Coordinate, y Coordinate, z Coordinate, total energy value W i .

[0053] (2) Map the total energy W Data

[0054] Build a 3D zero matrix Data of m × n × p in MATLAB, and map the fourth column data W in the total energy exported from COMSOL W i data into the matrix Data. Mapping rule: First, divide each direction coordinate into several intervals, that is x Direction division m intervals ( x 1, x 2, ……, x m ), y Direction division n intervals ( y 1, y 2, ……, y n ), z Direction division p intervals ( z 1, z 2, ……, z p ). Then, if W ( x , y , z ) in the data W i The corresponding coordinates meet the interval coordinates, then W iThe data is mapped to the corresponding positions of the Data matrix, and the number of data at the corresponding positions is recorded. Finally, the average value of the data in each interval is taken (i.e., the number of rows, columns, and layers of the 3D matrix Data can correspond) W t in the data x , y , z coordinates, and the values in the Data matrix correspond W t to the energy values). Among them, m =( x max - x min ) / d x , n =( y max - y min ) / d y , p =( z max - z min ) / d z ; x max and x min are respectively W ( x , y , z , W i )the coordinates in x the maximum and minimum values, and d x is x the coordinate step size; y max and y min are respectively W ( x , y , z , W i )the coordinates in y the maximum and minimum values, and d y is y the coordinate step size; z max and z min are respectively W ( x , y , z , W i )the coordinates in z the maximum and minimum values, and dz is z the coordinate step size.

[0055] (3)Calculate the risk coefficient of the three-pillar insulator

[0056] First, in the z direction, starting from the first data in the first layer of the matrix Data (i.e., Data(1, 1, 1)), find the minimum value among the 9 adjacent data directly below the first layer in the second layer of the matrix, record this value and its position; then, find the minimum value among the 9 adjacent data directly below the minimum value data in the second layer in the third layer, record this value and its position; and so on, to obtain the minimum value and its position in all layers; and so on, to obtain the values and their corresponding positions on the m × n data as the starting point m × n paths. Compare the minimum cumulative value of the energy data and the corresponding position among all paths, and calculate the maximum risk coefficient of the insulator according to Formula 2.

[0057] (4)Construct the breakdown path

[0058] Import the position coordinates of the path with the maximum risk coefficient into COMSOL to construct the breakdown path with the maximum risk coefficient.

[0059] Compared with the prior art, the beneficial effects brought by the technical solution of the present invention are:

[0060] The present invention first proposes an evaluation model for the risk coefficient of the insulation margin of an insulator under the combined action of electrical and mechanical loads, which can effectively calculate the risk coefficient of the insulation margin of the insulator. And the implementation process of the present invention is simple, has strong practicability, high flexibility, and can be widely promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is a flowchart of the method for evaluating the risk coefficient of the insulation margin of the three-pillar insulator of UHV GIL according to the present invention.

[0062] Figure 2 is a geometric structure diagram of the three-pillar insulator according to the present invention.

[0063] Figure 3 is an electric field distribution diagram of the three-pillar insulator according to the present invention.

[0064] Figure 4 is a stress distribution diagram of the three-pillar insulator according to the present invention.

[0065] Figure 5 is an energy distribution diagram of the three-pillar insulator according to the present invention.

[0066] Figure 6 This is the breakdown channel diagram of the three - pillar insulator of the present invention.

[0067] Reference numerals: 1 - three - pillar insulator, 2 - outer shell, 3 - high - voltage conductor, 4 - metal insert. Specific implementation mode

[0068] The present invention will be further described below with reference to the accompanying drawings.

[0069] The present invention proposes a simulation method for the explosion and breakdown of a three - pillar insulator of UHV GIL. Under the framework of the dielectric phase - field theory, a phase - field model is constructed to describe the explosion and breakdown evolution of the three - pillar insulator under the action of electrical and mechanical loads. Based on this model, the explosion and breakdown morphology of the three - pillar insulator under extreme electrical and mechanical loads is obtained, and the influence of electrical and mechanical loads on the internal explosion and breakdown evolution law of the three - pillar insulator is explored.

[0070] The simulation method for the explosion and breakdown of the three - pillar insulator of UHV GIL in the present invention, as Figure 1 shown, the specific implementation process includes the following steps:

[0071] Step 1: Measure and obtain material parameters

[0072] Perform uniaxial tensile and broadband dielectric spectroscopy tests on the three - pillar insulator with epoxy resin / aluminum oxide composite materials respectively to obtain the parameters of the epoxy resin / aluminum oxide composite materials, including: the elastic modulus of the epoxy resin / aluminum oxide composite material Y p (for example Y p is 11290 MPa), the Poisson's ratio of the epoxy resin / aluminum oxide composite material mu (for example mu is 0.4), the tensile strength of the epoxy resin / aluminum oxide composite material σ p (for example σ p is 70 MPa), the relative dielectric constant of the epoxy resin / aluminum oxide composite material ε p (for example ε p is 5.5); conduct AC breakdown tests on epoxy resin / aluminum oxide composite material specimens with different thicknesses and obtain their breakdown field strengths E b .

[0073] Relationship between breakdown field strength and thickness

[0074]

[0075] Step 2: Establish a geometric model of the three - pillar insulator

[0076] Based on the COMOSL finite element software, a geometric model of the 1100 kV HVAC-GIL three-pillar insulator is established, and the mesh generation of the geometric model of the three-pillar insulator is carried out; among them, the geometric model of the three-pillar insulator includes a high-voltage conductor 3, three-pillar insulators 1, and a housing 2 nested in sequence from the inside to the outside along the coaxial line. Metal inserts 4 are provided between the three ends of the three-pillar insulator 1 and the housing 2, as Figure 2 shown. Among them, the high-voltage conductor 3 is set as a hollow structure.

[0077] Step 3: Calculate the total energy of the three-pillar insulator

[0078] (1) Establish the electric field control equation

[0079] The electric field strength is solved according to the Poisson equation of the electrostatic field:

[0080]

[0081] In the formula, ε r is the relative permittivity of the three-pillar insulator material; E is the electric field strength, kV / mm; is the electric potential, kV.

[0082] Boundary conditions: The potential of the high-voltage conductor is set to 1100 kV, and the housing is grounded.

[0083] (2) Establish the stress field control equation

[0084] Assume that the three-pillar insulator material is a linear elastic material, and the stress distribution is solved according to Hooke's law:

[0085]

[0086] In the formula, σ is the normal stress, Pa; T is the shear stress, Pa; ν and are the elastic deformations under normal stress and shear stress respectively; Y is the elastic modulus of the three-pillar insulator material, Pa; G is the shear modulus of the three-pillar insulator material Pa.

[0087] Boundary conditions: The high-voltage conductor is subjected to gravity, and the metal insert is set as a fixed constraint.

[0088] (3) Calculate the total energy

[0089] Based on the above control equations, the electric field and stress distributions are calculated, and the total energy is calculated according to the following formula W :

[0090]

[0091] Among them, W ele is the electrostatic energy, Pa; W mec is the strain energy, Pa.

[0092] Assume that the three - pillar insulator is a linear dielectric with a dielectric constant, W ele which is given by the following formula:

[0093]

[0094] where ε 0 is the relative dielectric constant of vacuum.

[0095] The strain energy W mec depends on the maximum value of the normal strain energy W mec1 and the shear strain energy W mec2 which is expressed as:

[0096]

[0097] Step 4, calculate the shape parameter of the breakdown model

[0098] Breakdown is developed from internal defects. Assume that a defect occurs in any region of the dielectric. Under the action of the electro - force field, this defect will cause a breakdown channel to form in the dielectric. Therefore, the probability of dielectric breakdown can be calculated by the probability of defect generation in the dielectric. The probability of defect generation in a certain region of the dielectric follows the Weibull distribution:

[0099]

[0100] where W is the energy of this region; W c0 is the size d The critical breakdown energy at 0; β is the shape parameter.

[0101] There is a dielectric with a thickness of d which is divided into n layer regions between two electrodes, and the length of each region is d 0, then n = d / d 0. When one or more regions on any path between the two electrodes generate defects, breakdown will occur. Then the probability of breakdown of this dielectric is:

[0102]

[0103] wherein W i is the total energy of the i th region.

[0104] For the flat specimen undergoing breakdown test, since the internal electric field is a uniform electric field, the above formula can be simplified as:

[0105]

[0106] Through equation transformation, the above formula can be derived as:

[0107]

[0108] The denominator of the exponent in the formula W c0 · n -1 / β can reflect the changing trend that the breakdown energy decreases with the increase of thickness, which conforms to the experimental law. Therefore, the critical breakdown energy d at a thickness of W c can be expressed as:

[0109]

[0110] According to the breakdown field strength E b of the epoxy resin / aluminum oxide composite material measured above and the relationship with the thickness d :

[0111]

[0112] The critical breakdown energy W c can be calculated according to the breakdown field strength E b measured in the experiment:

[0113]

[0114] wherein, ε 0 is the vacuum permittivity, ε r is the relative permittivity of the dielectric material. Therefore, from the equality of formulas 12 and 14, we can obtain:

[0115]

[0116] According to the relationship between the breakdown field strength and thickness of epoxy resin / aluminum oxide, using the fitting formula 13, we can obtain β = 1.7.

[0117] Step Five, calculate the risk assessment coefficient of the three-pillar insulator

[0118] (1) Export the total energy W Data

[0119] Calculate the total energy in the COMSOL software W ( x , y , z , W i ), and then export the data. W Contains 4 columns of data, namely x Coordinate y Coordinate z Coordinate, total energy value W i .

[0120] (2) Map the total energy W Data

[0121] Construct a 3D zero matrix Data of 20×20×20 in MATLAB, and map the fourth column data W in the total energy exported from COMSOL W i data into the matrix Data. Mapping rule: First, divide each direction coordinate into several intervals, that is x Direction is divided into 20 intervals ( x 1, x 2, ……, x 20 ), y Direction is divided into 20 intervals ( y 1, y 2, ……, y 20 ), z Direction is divided into p intervals ( z 1, z 2, ……, z 20 ). Then, if W ( x , y , z ) in the data W i corresponding coordinates match the interval coordinates, map the W i data to the corresponding position in the Data matrix, and record the data quantity at the corresponding position. Finally, take the average value of the data in each interval (that is, the rows, columns, and layers of the 3D matrix Data can correspond to the W t data in x, y , z Coordinates, and the values in the Data matrix correspond W to the energy values).

[0122] (3) Calculate the risk coefficient of the three-pillar insulator

[0123] First, in the z direction, starting from the first data in the first layer of the matrix Data (i.e., Data(1, 1, 1)), find the minimum value among the 9 adjacent data directly below the first layer in the second layer of the matrix, record this value and its position; then, find the minimum value among the 9 adjacent data directly below the minimum value data in the second layer in the third layer, record this value and its position; and so on, to obtain the minimum value and its position in all layers; and so on, to obtain the values and their corresponding positions on 20×20 paths starting from the 20×20 data in the first layer of Data. Compare the minimum cumulative value of the energy data and the corresponding position among all paths, and calculate the maximum risk coefficient of the insulator according to Formula 2.

[0124] (4) Construct the breakdown path

[0125] Import the position coordinates of the path with the maximum risk coefficient into COMSOL to construct the breakdown path with the maximum risk coefficient, as shown in Figure 6 .

[0126] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific functions and working processes. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. These all fall within the protection scope of the present invention.

Claims

1. A method for evaluating the insulation margin risk coefficient of a three-pillar insulator of UHV GIL, characterized in that, It includes the following steps: Step 1: Measure and obtain material parameters The three - pillar insulators are respectively subjected to uniaxial tension and broadband dielectric spectroscopy tests using epoxy resin / aluminum oxide composites to obtain the parameters of the epoxy resin / aluminum oxide composites, including: the elastic modulus of the epoxy resin / aluminum oxide composites Y p , the Poisson's ratio of the epoxy resin / aluminum oxide composites mu , the tensile strength of the epoxy resin / aluminum oxide composites σ p , the relative dielectric constant of the epoxy resin / aluminum oxide composites ε p . An AC breakdown test is carried out on epoxy resin / aluminum oxide composite specimens with different thicknesses and their breakdown field strengths are obtained E b ; Step 2: Establish a geometric model of a three-pillar insulator Based on the COMOSL finite element software, establish a geometric model of a 1100kV HVAC-GIL three-pillar insulator, and perform mesh division on the geometric model of the three-pillar insulator; among them, the geometric model of the three-pillar insulator includes a high-voltage conductor, three-pillar insulators, and a housing embedded coaxially from the inside to the outside in sequence, and metal inserts are provided between the three ends of the three-pillar insulators and the housing; Step 3: Calculate the total energy of the three-pillar insulator (1) Establish an electric field control equation The electric field strength is solved according to the Poisson equation of the electrostatic field: Wherein, ε r is the relative permittivity of the three-pillar insulator material; E is the electric field strength, kV / mm; is the electric potential, kV; Boundary conditions: The potential of the high-voltage conductor is set to 1100 kV, and the housing is grounded; (2) Establish a stress field control equation Assume that the material of the three-pillar insulator is a linear elastic material, and the stress distribution is solved according to Hooke's law: Where, σ is the normal stress, in Pa; T is the shear stress, in Pa; ν and are the elastic deformations under normal stress and shear stress respectively; Y is the elastic modulus of the three-pillar insulator material, in Pa; G is the shear modulus of the three-pillar insulator material, in Pa; Boundary conditions: The high-voltage conductor is subjected to gravity, and the metal insert is set as a fixed constraint; (3) Calculate the total energy Calculate the electric field and stress distributions based on the above control equations, and calculate the total energy according to the following formula W : wherein, W ele is the electrostatic energy, Pa; W mec is the strain energy, Pa; Assume that the three-pillar insulator is a linear dielectric with a dielectric constant, W ele which is given by the following formula: Among them ε 0 is the relative permittivity of vacuum; Strain energy W mec depending on the maximum of the normal strain energy W mec1 and the shear strain energy W mec2 which is expressed as: Step 4: Calculate the shape parameters of the breakdown model Breakdown is developed from internal defects. Assume that a defect occurs in any area of the dielectric, then this defect will cause a breakdown channel to form in the dielectric under the action of the electro-mechanical field. Therefore, the probability of dielectric breakdown can be calculated by the probability of a defect occurring in the dielectric; the probability of a defect occurring in a certain area within the dielectric follows the Weibull distribution: Among them W is the energy of this area; W c0 is the dimension d is the critical breakdown energy at 0; β is the shape parameter; There is a dielectric thickness of d , which is divided into n layer regions between two electrodes, and the length of each region is d 0, then n = d / d 0; When defects occur in any one or more regions on a certain path between two electrodes, breakdown will occur. Then the probability of breakdown of this dielectric is: Among them W i is the total energy of the i th area; For a flat specimen undergoing a breakdown test, the internal electric field is a uniform electric field, so the above formula is simplified to: After equation transformation, the above formula can be derived as: The denominator of the exponent in the formula W c0 · n -1 / β It can reflect the change trend that the breakdown energy decreases with the increase of thickness, which conforms to the experimental law. Therefore, the critical breakdown energy d at a thickness of W c can be expressed as: According to the breakdown field strength of the epoxy resin / aluminum oxide composite material measured above E b and the thickness d relationship: Critical breakdown energy W c It can be calculated based on the breakdown field strength measured in the experiment E b as follows: Therefore, according to the equality of formulas (12) and (14), we can obtain: Obtained according to the relationship between the breakdown field strength and thickness of epoxy resin / aluminum oxide, using the fitting formula (13) β ; Step 5: Calculate the risk assessment coefficient of the three-pillar insulator (1)Derive the total energy W Data Calculate the total energy in COMSOL software W ( x , y , z , W i ), and then export the data; W It contains 4 columns of data, namely x coordinates, y coordinates, z coordinates, and the total energy value W i ; (2)Mapping the total energy W Data Construct a m × n × p 3D zero matrix Data in MATLAB, and map the fourth column data W in the total energy W i exported from COMSOL to the matrix Data; Mapping rule: First, divide the coordinates in each direction into several intervals, that is, x direction division m intervals ( x 1, x 2, ……, x m ), y direction division n intervals ( y 1, y 2, ……, y n ); Then, if z direction division p intervals ( z 1, z 2, ……, z p ); Then, if the data W ( x , y , z ) W i corresponding coordinates match the interval coordinates, map the W i data to the corresponding position in the Data matrix, and record the number of data at the corresponding position. Finally, take the average value of the data in each interval (that is, the rows, columns, and layers of the 3D matrix Data can correspond to the W t coordinates in the x , y , z data, and the values in the Data matrix correspond to the W t energy value); Among them, m =( x max - x min ) / d x , n =( y max - y min ) / d y , p =( z max - z min ) / d z ; x max and x min are respectively W ( x , y , z , W i ) the maximum and minimum values of the coordinates in, d x is x the x coordinate step size; y max and y min are respectively W ( x , y , z , W i ) the maximum and minimum values of the coordinates in, d y is y the y coordinate step size; z max and z min are respectively W ( x , y , z , W i ) the maximum and minimum values of the coordinates in, d z is z the z coordinate step size; (3) Calculate the risk coefficient of the three-pillar insulator First, in the z direction, starting from the first data in the first layer of the matrix Data (i.e., Data(1, 1, 1)), find the minimum value among the 9 data adjacent directly below the first layer in the second layer of the matrix, record this value and its position; then, find the minimum value among the 9 data adjacent directly below the minimum value data in the second layer in the third layer, record this value and its position; and so on to obtain the minimum value and its position in all layers; and so on to obtain the values and their corresponding positions on the m × n data as the starting point m × n paths; compare the minimum cumulative value of the energy data and the corresponding position among all paths, and calculate the maximum risk coefficient of the insulator according to formula (2); (4) Construct a breakdown path Import the position coordinates of the path with the maximum risk coefficient into COMSOL to construct a breakdown path with the maximum risk coefficient.

2. The insulation margin risk coefficient evaluation method for a UHV GIL three-pillar insulator according to claim 1, characterized in that The boundary conditions described in Step 3 are not limited to applying gravity to the guide rod, but also include external forces in different directions.

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