Gas-insulated rigid power transmission line with helical support structure and method for optimizing the same

Abstract

The application provides a new type of gas insulated rigid power transmission line with a spiral support structure and an optimization method thereof, which comprises three support insulators, a high-voltage conductor, a grounding shell, a high-voltage side / grounding side metal insert, a spiral metal ring and a roller. Compared with the original structure, the spiral metal ring and the roller are used to effectively improve the assembly convenience. The improved stable triangular support structure significantly improves the mechanical strength and stability, avoids the tilting and fracture risks of the three single support insulators caused by unbalanced stress, and can meet the support of conductors with different GIL arrangement angles. The application designs the structure of the new type of spiral support insulator, effectively reduces the electric field and stress of the insulating support insulator, improves the insulating performance, and improves the reliability of the safe operation of the power transmission line.

Description

Technical Field

[0001] This invention belongs to the field of computational electricity and mechanics, and relates to a novel design method for ultra-high voltage GIL (Gas Insulator) support insulator structures. More specifically, it relates to a gas-insulated rigid transmission line with a helical support structure and its optimization method. Background Technology

[0002] Gas-insulated transmission lines (GILs) are metal-encased transmission equipment widely used in power systems due to their high reliability, strong environmental adaptability, and lack of secondary pollution. The support insulators widely used in GILs primarily serve as insulation and support, and their insulation performance largely determines the safety and stability of the GIL. However, in recent years, three-support insulators have frequently experienced breakdown and rupture failures during operation, seriously threatening the safety of the entire transmission system. Strong electric fields and high mechanical stresses experienced by insulators in complex environments are significant contributing factors to insulation breakdown failures. Insulator structural design is a direct means of achieving uniform electric fields and reducing stress.

[0003] Traditional single-support insulator GIL structure, such as Figure 1 As shown, 1 is the supporting insulator, 2 is the grounding side insert, 3 is the high-voltage side insert, 4 is the high-voltage conductor, and 5 is the grounding outer shell. Traditionally, a single-support insulator is positioned directly below the high-voltage conductor and fixed to the outer shell by screws at the grounding insert.

[0004] Traditional single-support insulator structures have the following problems:

[0005] 1. Traditional insulators are fixed to the casing via grounding inserts. During installation, three single-support insulators in the same direction can cause the conductor to deviate from the center of the GIL (Gas Insulator Line), resulting in an imbalance of forces on the three insulators. 2. The weight of the GIL conductor and the mechanical stress generated by thermal expansion and contraction can lead to tilting or breakage of the three single supports in the same direction. 3. Single-support insulators are only suitable for fixed insulators and are insufficient for applications requiring sliding insulators. 4. Traditional support insulators only provide vertical support and are only suitable for horizontally arranged GIL lines. The actual GIL arrangement angle varies depending on the location; for example, vertically arranged GILs are also included. Traditional single-support insulators are insufficient for supporting vertically arranged GILs.

[0006] Therefore, there is an urgent need to develop a new type of supporting insulator to achieve coordinated control of the insulator's electric field and stress, thereby reducing its risk of bursting and breakdown. Summary of the Invention

[0007] Improving the insulation properties of insulators has become a problem that urgently needs to be solved by those skilled in the art.

[0008] To address the aforementioned problems, this invention proposes a gas-insulated rigid transmission line with a helical support structure, such as... Figure 2 As shown, the system includes three supporting insulators 1, 2, and 3, which are separated along the conductor axis and differ in radial angle by 120°; a high-voltage conductor 4; a grounding shell 5; high-voltage / grounding side metal inserts 8 and 9, which connect the supporting insulators to the conductor / shell and reduce the electric field at the insulator ends; a spiral metal ring 6, which connects the three grounding metal inserts and ensures that the three metal inserts are at the same potential; and a roller 7, which is installed in the gap between the spiral metal ring and the grounding shell and can assist the three insulators and conductors in being pushed into the GIL housing simultaneously, effectively improving assembly convenience.

[0009] Furthermore, to enhance the insulation performance of the supporting insulator, this invention employs an optimization algorithm to optimize the shape parameters of the novel insulator, achieving coordinated control of the electric field and stress of the supporting insulator, including the following steps:

[0010] Step 1:

[0011] A geometric model of a novel gas-insulated rigid transmission line with a spiral support structure was established using SOLIDWORKS finite element software, and the insulator structure was parameterized.

[0012] Step Two:

[0013] ①Establish the electric field control equations

[0014] The current continuity equation is used to calculate the electric field distribution under DC voltage, as shown below:

[0015]

[0016] Where E is the DC steady-state electric field; γ is the conductivity of the insulating material;

[0017] Boundary conditions: The potential of the high-voltage conductor is set to 800kV, and the outer casing is grounded;

[0018] Set the electrical conductivity and relative permittivity of each component material;

[0019] ②Establish the mechanical stress control equation

[0020] Assuming the material is linearly elastic, stress and strain can be solved using the following equations:

[0021]

[0022] σ=(Y,G):v

[0023] Among them, F vσ is the volume force applied to the HV conductor; σ is the stress tensor; v is the strain tensor; Y is the Young's modulus of the dielectric material; G is the shear modulus of the material.

[0024] Boundary conditions: The potential of the high-voltage conductor is set to 6 times the gravity, and the metal insert is set as a fixed constraint;

[0025] Set the density, Young's modulus, and Poisson's ratio of the materials for each component;

[0026] ③ Calculate the electric field and stress

[0027] The electric field and stress control equations were solved using COMSOL to calculate the maximum internal electric field strength and maximum mechanical stress.

[0028] Step Two:

[0029] ① Set constraints

[0030] Shape parameter constraints: In the finite element analysis model of the electric field of the supporting insulator established in step one, the controlled variable method is used to allow the shape parameters to be optimized to vary within a certain range. The objective function is calculated when the parameters change, and the range of variation of the optimized shape parameters is shown in the following formula:

[0031] x 1min ≤x1≤x 1max

[0032] x 2min ≤x2≤x max

[0033] r 1min ≤r1≤r 1max

[0034] r 2min ≤r2≤r 2max

[0035] x 3min ≤x3≤x 3max

[0036] h 3min ≤h3≤h 3max

[0037] r 3min ≤r3≤r 3max

[0038] Where 1 is the top radius of the support column x1, 2 is the bottom radius of the support column x2, 3 is the top chamfer r1 of the support leg, 4 is the bottom chamfer r2 of the support leg, 5 is the radius of the insert x3, 6 is the depth of the insert h3, and 7 is the chamfer of the insert r3; the subscript min indicates the minimum value of each shape parameter, and the subscript max indicates the maximum value of each shape parameter.

[0039] The performance constraints are as follows:

[0040] E tmax <6kV / mm

[0041] σ max <20MPa

[0042] Among them, E tmax To support the maximum surface electric field of the insulator; σ max To support the maximum mechanical stress of the insulator;

[0043] ② Calculate the objective function

[0044] With the optimization objectives of reducing the maximum internal electric field strength and the maximum mechanical stress, the objective function expression is as follows:

[0045]

[0046] Among them, E imax The maximum internal electric field of the supporting insulator, E i0max The initial structure supports the maximum internal electric field of the insulator; σ max To support the maximum mechanical stress of the insulator, σ 0max The initial structure supports the maximum mechanical stress of the insulator;

[0047] Using the E of the insulator in step two imax With σ max Calculate the objective function;

[0048] Step 3:

[0049] Based on the constraints in step two, a genetic algorithm is used to optimize the shape parameters of the insulator, thereby minimizing the objective function and obtaining the optimal shape parameters under the corresponding optimization objective function.

[0050] 1) Initial parent generation: First, under the constraint of shape parameters, randomly generate m insulators with different shapes;

[0051] 2) Evaluation: Calculate the objective function for each supporting insulator according to step two, determine whether it meets the performance index constraints in step two, and set the objective function of insulators that do not meet the constraints to 10;

[0052] 3) Selection: Prioritize insulators with smaller objective functions in the initial population;

[0053] 4) Crossover: Select two insulators and randomly swap their shape parameters with a crossover probability of p, thereby creating a completely new individual (offspring);

[0054] 5) Mutation: Randomly change the shape parameters of the offspring, with a mutation probability of q, to ​​obtain a new individual;

[0055] 6) Evaluation: Calculate the objective function of all insulators after the update, set the objective function of insulators that do not meet the constraints to 10, and record the overall optimal result and the local optimal result;

[0056] 7) Repeat steps 3) to 6) above until the maximum number of iterations n is reached or the objective function remains unchanged after multiple iterations;

[0057] 8) Return results: The final output is the individual parameter combination with the lowest objective function value that satisfies all constraints, which is the optimal design scheme of the insulator structure, and the corresponding optimized single-support insulator model results are saved.

[0058] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0059] This invention provides a novel gas-insulated rigid transmission line with a helical support structure, comprising three supporting insulators separated by 2m along the conductor axis and 120° apart along the conductor radial angle; a high-voltage conductor; a grounding shell; high-voltage / grounding side metal inserts, which connect the supporting insulators to the conductor / shell and reduce the electric field at the insulator ends; a helical metal ring, which connects the three grounding metal inserts and ensures that the three metal inserts are at the same potential, with screw holes at the bottom of the insulators for connecting rollers and the grounding shell; and rollers installed in the gap between the helical metal ring and the shell, which can assist the three insulators and conductors in being pushed into the GIL shell simultaneously, effectively improving assembly convenience.

[0060] The main improvements of the novel helical support structure gas-insulated rigid transmission line provided by this invention are as follows: three supporting insulators in the same direction are arranged in different directions to form a stable triangular support structure, which significantly improves its mechanical strength and stability; a helical metal ring and a slide rail are set to ensure that the three insulators and the conductor are pushed into the GIL shell synchronously, and to ensure that the conductor is arranged in the center of the GIL pipe so that it is balanced by force; the risk of tilting and breakage of the three single supporting insulators caused by unbalanced force is avoided; the helical metal ring can be fixed or slidable to be used in sliding or fixed insulator situations; and conductor support can meet different GIL arrangement angles.

[0061] Another improvement of this invention focuses on the improvement of the novel spiral support structure. Through structural design, the electric field and stress of the insulation support structure are effectively reduced, its insulation performance is improved, and the reliability of the safe operation of the transmission line is enhanced. Attached Figure Description

[0062] Figure 1This is a traditional UHVDC GIL support insulator structure. 1 is the traditional support insulator, 2 is the low-voltage side insert, 3 is the high-voltage side insert, 4 is the high-voltage conductor, and 5 is the grounding shell.

[0063] Figure 2 This invention relates to a novel gas-insulated rigid transmission line with a helical support structure. It includes supporting insulators 1, 2, and 3; a high-voltage conductor 4; a grounding shell 5; a helical metal ring 6; a roller 7; and high-voltage / grounding side metal inserts 8 and 9.

[0064] Figure 3 This is a flowchart of the insulator structure design based on genetic algorithm of the present invention.

[0065] Figure 4 Key shape parameters of the supporting insulator of this invention:

[0066] Where 1 is the support top radius x1, 2 is the support bottom radius x2, 3 is the chamfer r1 at the top of the leg, 4 is the chamfer r2 at the bottom of the leg, 5 is the insert radius x3, 6 is the insert depth h3, and 7 is the insert chamfer r3.

[0067] Figure 5 The following are the optimized structures of the novel helical support insulator of this invention:

[0068] 1 represents the state before optimization, and 2 represents the state after optimization.

[0069] Figure 6 The electric field distribution of the novel spiral-supported insulator of this invention before and after optimization is shown in (a) before optimization and (b) after optimization.

[0070] Figure 7 The stress distribution of the novel spiral-supported insulator before and after optimization is shown in the following figures: (a) before optimization, (b) after optimization. Detailed Implementation

[0071] The present invention will now be further described with reference to the accompanying drawings.

[0072] This invention proposes a gas-insulated rigid transmission line with a helical support structure, such as... Figure 2As shown, the system includes three supporting insulators 1, 2, and 3, which are 2m apart along the conductor axis and 120° apart along the conductor radial angle; a high-voltage conductor 4; a grounding shell 5; high-voltage / grounding side metal inserts 8 and 9, which connect the supporting insulators to the conductor / shell and reduce the electric field at the insulator ends; a spiral metal ring 6, which connects the three grounding metal inserts and ensures that the three metal inserts are at the same potential; and a roller 7, installed in the gap between the spiral metal ring and the shell, which helps to push the three insulators and conductors into the GIL shell synchronously, effectively improving assembly convenience. Compared with the original structure, this invention utilizes a spiral metal ring and roller to effectively improve assembly convenience. The improved structure is a stable triangular support structure, which significantly improves its mechanical strength and stability; it avoids the risk of tilting and breakage of the three single supporting insulators due to unbalanced forces; and it can meet the conductor support requirements of different GIL arrangement angles. This invention designs a new type of spiral supporting insulator to effectively reduce the electric field and stress of the supporting insulator, improve its insulation performance, and enhance the reliability of the safe operation of the transmission line.

[0073] To improve the insulation performance of supporting insulators, this invention employs an optimization algorithm to optimize the shape parameters of a novel insulator, achieving coordinated control of the electric field and stress of the supporting insulator. The process includes the following steps, with a detailed flowchart shown below. Figure 3 As shown:

[0074] Step 1:

[0075] A geometric model of a novel gas-insulated rigid transmission line with a helical support structure was established using SOLIDWORKS finite element software, and the insulator structure was parameterized, such as... Figure 4 As shown.

[0076] Step Two:

[0077] ①Establish the electric field control equations

[0078] The current continuity equation is used to calculate the electric field distribution under DC voltage, as shown below:

[0079]

[0080] Where E is the DC steady-state electric field; γ is the conductivity of the insulating material.

[0081] Boundary conditions: The potential of the high-voltage conductor is set to 800kV, and the outer casing is grounded.

[0082] Table 2 shows the material electrical parameters of the present invention.

[0083] Table 2

[0084]

[0085] The electrical conductivity and relative permittivity of each component material are set as shown in Table 2, where γ0 and ε are the electrical conductivity and permittivity of the epoxy / alumina composite material, respectively.

[0086] ②Establish the mechanical stress control equation

[0087] Assuming the material is linearly elastic, stress and strain can be solved using the following equations:

[0088]

[0089] σ=(Y,G):v (2)

[0090] Where F v σ is the volume force applied to the HV conductor; σ is the stress tensor; v is the strain tensor; Y is the Young's modulus of the dielectric material; G is the shear modulus of the material.

[0091] Boundary conditions: The potential of the high-voltage conductor is set to 6 times the gravity, and the metal insert is set as a fixed constraint. Table 3 shows the material mechanical parameters of this invention.

[0092] Table 3

[0093]

[0094] The density, Young's modulus, and Poisson's ratio of each component material are set as shown in Table 3.

[0095] ③ Calculate the electric field and stress

[0096] The electric field and stress control equations were solved using COMSOL to calculate the maximum internal electric field strength and maximum mechanical stress.

[0097] Step 3:

[0098] ① Set constraints

[0099] Shape parameter constraints: In the finite element analysis model of the electric field of the supporting insulator established in step one, the controlled variable method is used to allow the shape parameters to be optimized to vary within a certain range. The objective function is calculated when the parameters change, and the range of variation of the optimized shape parameters is shown in the following formula:

[0100] 40≤x1≤80

[0101] 40≤x2≤80

[0102] 1≤r1≤9

[0103] 1≤r²≤18

[0104] 20≤x3≤40

[0105] 30≤h3≤70

[0106] 1≤r3≤18

[0107] Wherein, 1 is the top radius of the support column x1, 2 is the bottom radius of the support column x2, 3 is the top chamfer r1 of the support leg, 4 is the bottom chamfer r2 of the support leg, 5 is the radius of the insert x3, 6 is the depth of the insert h3, and 7 is the chamfer r3 of the insert;

[0108] Table 1 shows the initial values ​​of the key shape parameters of this invention.

[0109] Table 1

[0110]

[0111] The performance constraints are as follows:

[0112] E tmax <6kV / mm

[0113] σ max <20MPa

[0114] Among them, E tmax To support the maximum surface electric field of the insulator; σ max To support the maximum mechanical stress of the insulator.

[0115] ② Calculate the objective function

[0116] With the optimization objectives of reducing the maximum internal electric field strength and the maximum mechanical stress, the objective function expression is as follows:

[0117]

[0118] Among them, E imax The maximum internal electric field of the supporting insulator, E i0max The maximum internal electric field of the initial structural support insulator is 17.47 kV / mm; σ max To support the maximum mechanical stress of the insulator, σ 0max The maximum mechanical stress of the initial structural support insulator is 16.04 MPa.

[0119] Using the E of the insulator in step two imax With σ max Calculate the objective function.

[0120] Step 3:

[0121] Based on the constraints in step two, a genetic algorithm is used to optimize the insulator shape parameters, thereby minimizing the objective function and obtaining the optimal shape parameters under the corresponding optimization objective function.

[0122] 1) Initial parent generation: First, 300 insulators with different shapes are randomly generated under the constraints of shape parameters.

[0123] 2) Evaluation: Calculate the objective function for each supporting insulator according to step two, and determine whether it meets the performance index constraints in step two. Set the objective function of insulators that do not meet the constraints to 10.

[0124] 3) Selection: Prioritize insulators with smaller objective functions in the initial population.

[0125] 4) Crossover: Select two insulators and randomly swap their shape parameters. The crossover probability is 0.75, thus creating a completely new individual (offspring).

[0126] 5) Mutation: Randomly change the shape parameters of the offspring with a mutation probability of 0.01 to obtain a new individual.

[0127] 6) Evaluation: Calculate the objective function of all insulators after the update, set the objective function of insulators that do not meet the constraints to 10, and record the overall optimal result and the local optimal result;

[0128] 7) Repeat steps 3) to 6) above until the maximum number of iterations of 200 is reached or the objective function remains unchanged after multiple iterations.

[0129] 8) Return results: The final output is the individual parameter combination with the lowest objective function value that satisfies all constraints, which is the optimal design scheme of the insulator structure, and the corresponding optimized single-support insulator model results are saved.

[0130] 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 specific functions and working processes described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the protection scope of the present invention.

Claims

1. A gas-insulated rigid transmission line with a helical support structure, comprising support insulators (1), (2), and (3), the three support insulators (1), (2), and (3) being separated along the conductor axial direction and differing by 120° along the conductor radial direction; a high-voltage conductor (4); a grounding shell (5); a high-voltage side metal insert (9) and a grounding side metal insert (8); a helical metal ring (6), the helical metal ring (6) connecting the three grounding side metal inserts (8); and a roller (7), installed in the gap between the helical metal ring (6) and the grounding shell (5), to assist the three support insulators (1), (2), and (3) in being pushed into the GIL shell synchronously with the high-voltage conductor (4).

2. The optimization method for a gas-insulated rigid transmission line with a helical support structure according to claim 1, characterized in that, Optimizing the shape parameters of insulating components to achieve coordinated control of the electric field and stress of the supporting insulator includes the following steps: Step 1: Establish a geometric model of a novel gas-insulated rigid transmission line with a spiral support structure based on SOLIDWORKS finite element software, and parameterize the insulator structure; Step Two: ①Establish the electric field control equations The current continuity equation is used to calculate the electric field distribution under DC voltage, as shown below: in, E It is a DC steady-state electric field; γ It is the electrical conductivity of insulating materials; Boundary conditions: The potential of the high-voltage conductor is set to 800kV, and the outer casing is grounded; Set the electrical conductivity and relative permittivity of each component material; ②Establish the mechanical stress control equation Assuming the material is linearly elastic, stress and strain can be solved using the following equations: in, F v It is the volume force applied to the HV conductor; σ It is the stress tensor; v It is the strain tensor; Y It is the Young's modulus of the dielectric material; G It is the shear modulus of the material; Boundary conditions: The load on the high-voltage conductor is set to 6 times the gravity, and the metal insert is set as a fixed constraint; Set the density, Young's modulus, and Poisson's ratio of the materials for each component; ③ Calculate the electric field and stress The electric field and stress control equations were solved using COMSOL to calculate the maximum internal electric field strength and maximum mechanical stress. Step 3: ① Set constraints Shape parameter constraints: In the finite element analysis model of the electric field of the supporting insulator established in step one, the controlled variable method is used to allow the shape parameters to be optimized to vary within a certain range. The objective function is calculated when the parameters change, and the range of variation of the optimized shape parameters is shown in the following formula: Where x1 is the top radius of the support column, x2 is the bottom radius of the support column, r1 is the top chamfer of the support leg, r2 is the bottom chamfer of the support leg, x3 is the radius of the insert, h3 is the depth of the insert, and r3 is the chamfer of the insert; the subscript min indicates the minimum value of each shape parameter, and the subscript max indicates the maximum value of each shape parameter. The performance constraints are as follows: in, E tmax To support the maximum surface electric field of the insulator; σ max To support the maximum mechanical stress of the insulator; ② Calculate the objective function With the optimization objectives of reducing the maximum internal electric field strength and the maximum mechanical stress, the objective function expression is as follows: in, E imax Supports the maximum internal electric field of the insulator. E i0max The initial structure supports the maximum internal electric field of the insulator; σ max To support the maximum mechanical stress of the insulator, σ 0max The initial structure supports the maximum mechanical stress of the insulator; Using the insulator in step two E imax and σ max Calculate the objective function; Step 3: Based on the constraints in step two, a genetic algorithm is used to optimize the insulator shape parameters, thereby minimizing the objective function and obtaining the optimal shape parameters under the corresponding optimization objective function.

3. The optimization method according to claim 2, characterized in that, Step three is described in detail below: 1) Initial parent generation: First, under the constraint of shape parameters, randomly generate m insulators with different shapes; 2) Evaluation: Calculate the objective function for each supporting insulator according to step two, determine whether it meets the performance index constraints in step two, and set the objective function of insulators that do not meet the constraints to 10; 3) Selection: Prioritize insulators with smaller objective functions in the initial population; 4) Crossover: Select two insulators and randomly swap their shape parameters with a crossover probability of p, thereby creating a completely new offspring. 5) Mutation: Randomly change the shape parameters of the offspring, with a mutation probability of q, to ​​obtain a new individual; 6) Evaluation: Calculate the objective function of all insulators after the update, set the objective function of insulators that do not meet the constraints to 10, and record the overall optimal result and the local optimal result; 7) Repeat steps 3) to 6) until the maximum number of iterations n is reached or the objective function remains unchanged after multiple iterations; 8) Return results: The final output is the individual parameter combination with the lowest objective function value that satisfies all constraints, which is the optimal design scheme of the insulator structure, and the corresponding optimized single-support insulator model results are saved.

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