Calculation method for GIL compensation section length in vertical shaft

Abstract

The application discloses a kind of shaft GIL compensation section length calculation method, including determining GIL bus compensation section length calculation parameter;Calculate the deformation variable of GIL bus shell in shaft lower section when operating;The shell length of compensation section is calculated;The maximum deformation variable of conductor is calculated, so as to design the length of compensation section according to the deformation variable of compensation section shell and the maximum deformation of conductor;The application solves the problem that there is difference between GIL design length and actual installation length when replacing shaft section GIL with self-controllable GIL different gas chamber, and the length of compensation section can be reasonably set by calculation, so as to eliminate length difference.

Description

Technical Field

[0001] This invention relates to the field of GIL pipeline maintenance technology, and in particular to an overhead LNG pipeline support structure with settlement compensation adjustment. Background Technology

[0002] Factors causing deformation of the GIL shell include axial compression due to the GIL's own weight, temperature rise and axial expansion caused by current flowing through the internal conductors, and elongation of the shell along the axial direction due to the axial force (blind plate force) caused by the SF6 gas inside the shell. When replacing different chambers of the vertical shaft GIL with an autonomous and controllable GIL, the above factors will cause a difference between the designed length and the actual installation length of the GIL. Therefore, it is necessary to design a method for calculating the length of the vertical shaft GIL compensation section to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a method for calculating the length of the compensation section of a vertical shaft GIL, which solves the problem of the difference between the designed length and the actual installed length of the GIL when replacing different chambers of the vertical shaft GIL with an autonomous and controllable GIL. The length of the compensation section can be reasonably set through calculation, thereby eliminating the length difference.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] The method for calculating the length of the GIL compensation section in a vertical shaft includes:

[0006] S1, determine the calculation parameters for the GIL bus compensation section length;

[0007] S2, calculates the deformation of the lower section of the GIL busbar shell during operation;

[0008] S3, Calculate the shell length of the compensation section;

[0009] S4, calculate the maximum deformation of the conductor, and then design the length of the compensation section based on the deformation of the compensation section shell and the maximum deformation of the conductor.

[0010] Preferably, in step S1, the calculation parameters for the length of the GIL bus compensation section include the thermal expansion and contraction due to ambient temperature during installation, the axial elongation of the hoisting section shell under its own weight, and the compression of the shell after hoisting and removal.

[0011] Preferably, in step S2, calculating the deformation of the lower section of the GIL busbar shell during operation includes:

[0012] S201, Calculate the axial thermal expansion and contraction of the housing caused by changes in ambient temperature during installation:

[0013] ΔL shell- Environment = α(t2-t1)L;

[0014] In the formula, α is the linear expansion coefficient of aluminum alloy material, t2 is the ambient temperature at the installation site, t1 is the reference temperature, i.e. the turning temperature at which the shell undergoes thermal expansion and contraction, and L represents the calculated length of the lower section of the GIL shell in the shaft.

[0015] S202, Calculate the axial elongation of all shells above the compensation section shell, i.e., the hoisting section shell, under its own weight;

[0016] S203, measure the compression of the shell after the upper part of the GIL is removed by hoisting, and then calculate the axial elongation of the shell under the gravity of the GIL that the compensation section needs to compensate.

[0017] Preferably, in step S202, calculating the axial elongation of all shells above the compensation section shell, i.e., the hoisting section shell, under its own weight includes calculating the axial elongation of the shell under its own weight when the bridge crane lifts the hoisting section shell, as follows:

[0018] Calculate the length L of the hoisting section shell. 吊装段 :

[0019] L 吊装段 =LL n ;

[0020] In the formula, L 吊装段 This represents the length of the hoisting shell of the GIL section after removing all shells below it; L represents the calculated length of the lower section of the GIL shell in the shaft; L n This represents the sum of the lengths of all shells below the hoisting section.

[0021] Calculate the mass M of the hoisting section 吊装 :

[0022] M 吊装 =MM n -M SF6 -M 绝缘子 ;

[0023] In the formula, M represents the total mass of the phase GIL, M n M represents the sum of the masses of all the shells below the hoisting section. SF6 M represents the mass of SF6 gas introduced into the GIL. 绝缘子 This represents the sum of the masses of the insulators installed in all the shells below the hoisting section shell;

[0024] Hang the top of the hoisting section shell on the crane hook, and set the calculated hoisting shell length L... 吊装段 and the mass M of the hoisting section 吊装The data is input into ANSYS software, and ANSYS calculations are used to obtain the axial elongation ΔL of the shell under its own weight during hoisting. 壳体自重拉伸 .

[0025] Preferably, in step S203, after removing the hook, only the lower end of the entire shell is fixed. At this time, it is only subject to the weight of the GIL itself, and the shell will undergo axial compression deformation. The maximum axial compression deformation ΔL of the GIL shell under its own weight is measured. 壳体自重压缩 .

[0026] Preferably, in step S203, the axial elongation of the shell under the action of GIL gravity that the compensation section shell needs to compensate for is as follows:

[0027] ΔL weight =ΔL 壳体自重拉伸 +ΔL 壳体自重压缩 ;

[0028] In the formula, a positive value represents stretching, and a negative value represents contraction.

[0029] Preferably, in step S3, the shell length of the compensation section is calculated as follows:

[0030] S301, Use a laser rangefinder to measure the required actual length L of the outer shell of the compensation section of the pipe at this time. 实际 ;

[0031] S302, Calculate the final length of the compensation section shell:

[0032] L 补偿段 =L 实际 +ΔL weight +ΔL shell-环境 ;

[0033] In the formula, ΔL shell-环境 The calculated length L of the lower section of the GIL shell in the shaft is calculated. The calculated length L includes the length of the hoisting section, the length below the hoisting section, and the sum of the final compensation section length.

[0034] Preferably, in step S3, the deformation of the conductor is calculated as follows:

[0035] ΔL 导体 =ΔL 导体自重 +ΔL 导体温升 ;

[0036] In the formula, ΔL 导体自重 The axial deformation caused by the conductor's gravity is directly calculated by inputting the measured conductor length into the ANSYS software; ΔL 导体温升This represents the axial deformation caused by the conductor's temperature rise. It is calculated by inputting the above data into ANSYS software, which includes the measured conductor length, the coefficient of linear expansion of the aluminum alloy material, and the allowable temperature rise under the conductor's rated current.

[0037] The beneficial effects of this invention are as follows:

[0038] This invention provides a calculation method for the compensation section GIL during shaft section replacement, taking into account the influence of GIL self-weight and temperature. When using an autonomous GIL for replacement, this method and the final calculation results can be used to determine the length of the replacement compensation section. This solves the problem of the difference between the designed GIL length and the actual installation length when replacing different chambers of the shaft section GIL with an autonomous and controllable GIL. The length of the compensation section can be reasonably set through calculation, thereby eliminating the length difference. Attached Figure Description

[0039] Figure 1 This is a flowchart of the method of the present invention;

[0040] Figure 2 This is a schematic diagram of the finite element analysis model of the conductor in a single standard segment in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram illustrating the load and constraint application method of the conductor in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram illustrating the temperature load and constraint application method of the conductor in an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram showing the maximum axial deformation of the conductor after thermal expansion calculated using ANSYS software in an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of the load and constraint application method when the self-weight of the GIL causes axial compression of the shell in an embodiment of the present invention;

[0045] Figure 7 This is a cloud diagram showing the deformation of the shell when the shell is axially compressed due to the self-weight of the GIL in an embodiment of the present invention.

[0046] Figure 8 This is a schematic diagram of the axial elongation of the shell caused by temperature rise and the shell temperature load and constraint application method in an embodiment of the present invention;

[0047] Figure 9 This is a cloud diagram of shell deformation caused by axial elongation of the shell in an embodiment of the present invention;

[0048] Figure 10 This is a schematic diagram in an embodiment of the present invention where two independent air chambers are considered as one air chamber;

[0049] Figure 11 This is a deformation contour map of the shell caused by the axial force induced by SF6 gas inside the shell in an embodiment of the present invention;

[0050] Figure 12 This is a schematic diagram illustrating the load and constraint application method of the hoisting section shell when calculating the axial elongation of the shell under its own weight during the lifting of the hoisting section shell by the bridge crane in an embodiment of the present invention.

[0051] Figure 13 This is a cloud diagram showing the axial deformation of the shell under its own weight when the bridge crane lifts the hoisting section shell in an embodiment of the present invention. Detailed Implementation

[0052] Example 1:

[0053] like Figure 1 As shown, the method for calculating the length of the GIL compensation section in a vertical shaft includes:

[0054] S1, determine the calculation parameters for the GIL bus compensation section length;

[0055] S2, calculates the deformation of the lower section of the GIL busbar shell during operation;

[0056] S3, Calculate the shell length of the compensation section;

[0057] S4, calculate the maximum deformation of the conductor, and then design the length of the compensation section based on the deformation of the compensation section shell and the maximum deformation of the conductor.

[0058] Preferably, in step S1, the calculation parameters for the length of the GIL bus compensation section include the thermal expansion and contraction due to ambient temperature during installation, the axial elongation of the hoisting section shell under its own weight, and the compression of the shell after hoisting and removal.

[0059] Preferably, in step S2, calculating the deformation of the lower section of the GIL busbar shell during operation includes:

[0060] S201, Calculate the axial thermal expansion and contraction of the housing caused by changes in ambient temperature during installation:

[0061] ΔL shell- Environment = α(t2-t1)L;

[0062] In the formula, α is the linear expansion coefficient of aluminum alloy material, t2 is the ambient temperature at the installation site, t1 is the reference temperature, i.e. the turning temperature at which the shell undergoes thermal expansion and contraction, and L represents the calculated length of the lower section of the GIL shell in the shaft.

[0063] S202, Calculate the axial elongation of all shells above the compensation section shell, i.e., the hoisting section shell, under its own weight;

[0064] S203, measure the compression of the shell after the upper part of the GIL is removed by hoisting, and then calculate the axial elongation of the shell under the gravity of the GIL that the compensation section needs to compensate.

[0065] Preferably, in step S202, calculating the axial elongation of all shells above the compensation section shell, i.e., the hoisting section shell, under its own weight includes calculating the axial elongation of the shell under its own weight when the bridge crane lifts the hoisting section shell, as follows:

[0066] Calculate the length L of the hoisting section shell. 吊装段 :

[0067] L 吊装段 =LL n ;

[0068] In the formula, L 吊装段 This represents the length of the hoisting shell of the GIL section after removing all shells below it; L represents the calculated length of the lower section of the GIL shell in the shaft; L n This represents the sum of the lengths of all shells below the hoisting section.

[0069] Calculate the mass M of the hoisting section 吊装 :

[0070] M 吊装 =MM n -M SF6 -M 绝缘子 ;

[0071] In the formula, M represents the total mass of the phase GIL, M n M represents the sum of the masses of all the shells below the hoisting section. SF6 M represents the mass of SF6 gas introduced into the GIL. 绝缘子 This represents the sum of the masses of the insulators installed in all the shells below the hoisting section shell;

[0072] Hang the top of the hoisting section shell on the crane hook, and set the calculated hoisting shell length L... 吊装段 and the mass M of the hoisting section 吊装 The data is input into ANSYS software, and ANSYS calculations are used to obtain the axial elongation ΔL of the shell under its own weight during hoisting. 壳体自重拉伸 .

[0073] Preferably, in step S203, after removing the hook, only the lower end of the entire shell is fixed. At this time, it is only subject to the weight of the GIL itself, and the shell will undergo axial compression deformation. The maximum axial compression deformation ΔL of the GIL shell under its own weight is measured. 壳体自重压缩 .

[0074] Preferably, in step S203, the axial elongation of the shell under the action of GIL gravity that the compensation section shell needs to compensate for is as follows:

[0075] ΔL weightt =ΔL 壳体自重拉伸 +ΔL 壳体自重压缩 ;

[0076] In the formula, a positive value represents stretching, and a negative value represents contraction.

[0077] Preferably, in step S3, the shell length of the compensation section is calculated as follows:

[0078] S301, Use a laser rangefinder to measure the required actual length L of the outer shell of the compensation section of the pipe at this time. 实际 ;

[0079] S302, Calculate the final length of the compensation section shell:

[0080] L 补偿段 =L 实际 +ΔL weight +ΔL shell-环境 ;

[0081] In the formula, ΔL shell-环境 The calculated length L of the lower section of the GIL shell in the shaft is calculated. The calculated length L includes the length of the hoisting section, the length below the hoisting section, and the sum of the final compensation section length.

[0082] Preferably, in step S3, the deformation of the conductor is calculated as follows:

[0083] ΔL 导体 =ΔL 导体自重 +ΔL 导体温升 ;

[0084] In the formula, ΔL 导体自重 The axial deformation caused by the conductor's gravity is directly calculated by inputting the measured conductor length into the ANSYS software; ΔL 导体温升 This represents the axial deformation caused by the conductor's temperature rise. It is calculated by inputting the above data into ANSYS software, which includes the measured conductor length, the coefficient of linear expansion of the aluminum alloy material, and the allowable temperature rise under the conductor's rated current.

[0085] Example 2:

[0086] Taking the lower section of shaft #3 of a certain unit as an example, the length of the compensation section shell is calculated when the shaft section is replaced. The specific steps are as follows:

[0087] Step 1: Determining the length of the GIL busbar casing during thermal expansion and contraction:

[0088] The lower section of the GIL busbar in shaft #3 consists of two chambers, upper and lower. The GIL busbar shell in the shaft has a "fixed point" at the bottom and "sliding points" spaced 11.5m apart in the middle. During operation, the lower end of the shell is fixed to the "fixed point" and constrained by the "sliding points." When the shell expands due to heat, it can only extend upwards along the shell's axis, i.e., the shaft wall. The expansion of the vertical section of the GIL shell is compensated by "angle compensation" expansion joints arranged horizontally on the GIL in the horizontal tunnel above the shaft. Therefore, when the GIL shell undergoes thermal expansion and contraction due to temperature changes, the calculated length of the shell is the length above the fixed point, i.e., L = 216360mm.

[0089] Step 2: Determining the temperature increment of the lower section of the GIL busbar shell in the vertical shaft:

[0090] The lower section of the GIL busbar housing in shaft #3 is located inside the shaft and is an indoor product. The ambient temperature is minimally affected by external factors. The temperature rise test is conducted at a rated current of 5000A. The maximum allowable temperature rise is selected based on the principle that "the part that can be touched by the operating personnel but is not required to be touched during normal operation shall not exceed 40K", that is, temperature rise Δt = 40K.

[0091] Step 3: Determining the temperature increment of the GIL conductor in the lower section of the shaft:

[0092] The temperature rise of the GIL conductor in the lower section of shaft #3 is determined according to the maximum allowable temperature rise of no more than 65K under the rated current of 5000A, that is, the temperature rise is taken as Δt=65K.

[0093] Step 4: Physical property study of GIL shell and conductor materials:

[0094] The GIL shell material is EN AW5754, corresponding to the domestic material 5754. If the conductor is selected from the commonly used material 6A02-T6, the physical property parameters of the shell material 5754 and the conductor material 6A02-T6 are shown in Table 1. The data in the table are from the literature "Mechanical Design Handbook", Volume 1, Fourth Edition.

[0095]

[0096] Table 1: Physical properties of shell and conductor materials.

[0097] Step 5: Determining the quality of the lower section of the GIL busbar casing and conductors in the shaft:

[0098] (1) Conductor mass:

[0099] The conductor is made of aluminum alloy tubing. Given the large length-to-diameter ratio of the conductor (length L = 11222 mm, outer diameter 180 mm, wall thickness 10 mm), to simplify the calculation and account for calculation errors, the conductor is approximated as a straight tube with an inner diameter of 160 mm and an outer diameter of 180 mm. The mass of a unit length of 180 × 10 of the aluminum tube is 14.4 kg / m. Therefore, the mass of the aluminum conductor is m = 11222 × 10⁻³ × 14.41³ = 161.743 kg.

[0100] (2) Quality of the lower section of the GIL busbar in the shaft:

[0101] The mass of the lower section of the GIL busbar in shaft #3 consists of four parts: shell mass, conductor mass, basin insulator mass, and SF6 gas mass.

[0102] The weight of the casing, the weight of the basin-type insulator, and the weight of the conductor can be categorized into the various modules of the GIL busbar in the lower section of shaft #3. Each module consists of a casing, insulators, and conductors. Specifically, the casing uses 512×6 aluminum tubing with a unit length weight of 25.739 kg / m; the conductor uses 180×10 aluminum tubing with a unit length weight of 14.413 kg / m; the insulator (airtight) weighs 47.5 kg, and the insulator (airtight) weighs 44.5 kg.

[0103] GIL consists of 15 standard modules (shell length 11500mm, conductor length 11222mm), four non-standard modules (shell lengths of 8400mm, 10960mm, 11400mm and 13100mm respectively; conductor lengths of 8122mm, 10682mm, 11122mm and 12822mm respectively), 17 insulators (ventilated) and 1 insulator (impermeable).

[0104] Ignoring the volume of insulators and conductors in the GIL, the volume of the lower section of the GIL shell in shaft #3 is:

[0105] V=π / 4×[(512-12)×10 -3 ] 2 ×216360×10 -3 =42.461m 3 ;

[0106] The SF6 gas filling the shell has a unit mass of 38.06 kg / m3 at rated pressure; the mass of SF6 gas is 42.461 × 38.06 = 1616.052 kg.

[0107] Therefore, the mass of the lower section of the GIL busbar in shaft #3 is:

[0108] M=(15×11500+8400+10960+11400+13100)×10 -3×25.736+(15×11222+8122

[0109] +10682+11122+12822)×10 -3 ×14.413+17×44.5+47.5+1616.052=11030.56kg.

[0110] Step Six: Calculate the deformation of the GIL conductor:

[0111] Factors that cause GIL conductor deformation during operation include: conductor gravity causing it to stretch along the axial direction, and conductor current carrying heat causing it to expand (elongate) along the axial direction. Since the conductor is a single-segment plug-in design, conductor deformation only affects its own segment and has no effect on adjacent segments. Therefore, it is only necessary to perform deformation calculations on the conductors in the GIL standard vertical module.

[0112] (1) Axial deformation caused by the conductor's gravity:

[0113] like Figure 2 The figure shows the finite element analysis model of the conductor in a single standard section; the calculated length of the conductor (180×10) in a single 11.5m standard section is 11222mm. During GIL operation, the conductor can be regarded as a suspended conductor with one end fixed and the other end able to freely extend and retract axially. The load and constraint application method of the conductor are shown in [reference needed]. Figure 3 As shown, under the influence of its own gravity, the conductor will elongate along the conductor axis.

[0114] The maximum axial deformation ΔL of the conductor under its own gravity was calculated using ANSYS software. 导体自重 =0.024091mm.

[0115] (2) Axial deformation caused by conductor temperature rise:

[0116] The conductor length L = 11222 mm, and the coefficient of linear expansion of the aluminum alloy material α = 2.3 × 10⁻⁶. -5 K -1 The allowable temperature rise Δt under a rated current of 5000A is 65K; the conductor operates in a suspended state with one end fixed and the other end free. The temperature load and constraint application method for the conductor are detailed in [link to relevant documentation]. Figure 4 The maximum axial deformation of the conductor after thermal expansion was calculated using ANSYS software. Figure 5 , △L 导体温升 =16.777mm.

[0117] (3) Maximum deformation of the conductor in the lower section of shaft #3 during GIL operation:

[0118] When the lower section of shaft #3 is running with GIL, the maximum deformation of the conductor is taken as the maximum deformation of the conductor in the standard vertical module of GIL. It consists of two parts: the maximum axial deformation of the conductor under its own weight and the axial elongation of the conductor when the temperature rise is allowed to be 65K, i.e., ΔL. 导体 =△L 导体自重 +△L 导体温升 =0.024091+16.777=16.801mm.

[0119] Step 7: Calculation of deformation of the GIL shell:

[0120] Factors causing deformation of the GIL casing include: axial compression of the casing due to the weight of the GIL itself; temperature rise of the casing caused by the current flowing through the conductors inside the GIL, leading to its expansion (elongation) along the axial direction; and axial force (i.e., blind plate force) caused by the SF6 gas inside the casing, leading to elongation of the casing along the axial direction.

[0121] (1) The self-weight of the GIL causes axial compression of the shell. The mass of the lower section of the GIL busbar in shaft #3 is M = 11030.56 kg. Ignoring the constraint of the horizontally installed corner expansion joint at the upper end of the shaft on the GIL shell, the GIL shell is considered as a column with a cross-section of 512 mm × 6 mm and a height of 216360 mm, fixed at the bottom and compressed only axially under its own weight. The load and constraint application method are detailed in [link to relevant documentation]. Figure 6 Using ANSYS software, the maximum axial compressive deformation ΔL of the GIL shell under its own weight was calculated. GIL自重-压缩 = -8.955mm, see the shell deformation contour map. Figure 7 .

[0122] (2) Temperature rise causes axial elongation of the shell:

[0123] The calculated length of the lower section of the GIL shell in the shaft is L = 216360 mm. The linear expansion coefficient of the aluminum alloy material is α = 2.3 × 10⁻⁵ K⁻¹. The allowable temperature rise of the shell under a conductor rated current of 5000 A is Δt = 40 K. Ignoring the constraint of the horizontally installed corner expansion joint at the upper end of the shaft on the GIL shell, the GIL shell is considered as a circular tube with a cross-sectional dimension of 512 mm × 6 mm, fixed at the bottom and elongating only axially after thermal deformation. The shell temperature load and constraint application method are detailed in [link to relevant documentation]. Figure 8 .

[0124] The axial deformation ΔL of the shell due to thermal expansion was calculated using ANSYS software. 壳体温升 =199.05mm, see the shell deformation contour map. Figure 9 .

[0125] (3) The axial force (i.e., blind plate force) caused by the SF6 gas inside the shell causes the shell to elongate along the axial direction:

[0126] The lower section of the GIL shell in shaft #3 consists of two independent air chambers. Ignoring the constraint of the horizontally installed corner expansion joint at the upper end of the shaft on the GIL shell, the GIL shell is treated as an air chamber fixed at the bottom and closed at both ends. Since the pressure on both sides of the air-insulator between the two independent air chambers is balanced, for the sake of simplified calculation, the air-insulator can be disregarded, and the two independent air chambers can be considered as one air chamber. See [link / details]. Figure 10 Under the action of SF6 gas pressure p = 0.82 MPa inside the shell, the shell elongates axially; the maximum axial deformation ΔL of the shell under the action of internal pressure is calculated using ANSYS software. 壳体内压 = 7.3766 mm; Deformation contour plot of the shell is shown below. Figure 11 .

[0127] Step 8: Determining the calculation parameters for the length of the compensation section shell during on-site replacement of the lower section of GIL in Shaft #3:

[0128] When replacing the entire lower section of the GIL in Shaft #3, all installation errors of the GIL shell are adjusted through the second-to-last section of the shell below the GIL, which is called the compensation section shell. After the other GIL shells are reinstalled according to the standard length in the drawings, the shell already installed above the compensation section shell is hoisted to its original installation position using a 20t bridge crane. The actual length required for this compensation section shell is measured using a laser rangefinder. Considering various factors that may affect the shell length during hoisting, the final installation length of the compensation section shell and conductor is determined. The standard section shell and conductor are then cut or lengthened to achieve the final installation length before reinstalling the compensation section shell, completing the GIL replacement. After replacement, when the GIL is filled with SF6 gas to the rated pressure and energized, the deformation of the vertical section shell must not exceed the adjustment range of the universal joint at a minimum ambient temperature of 0.3℃ and a maximum temperature of 40℃. The axial gap after the moving contact of the vertical section conductor is inserted into the stationary contact is within the range of 35mm-50mm. Therefore, the accuracy of the compensation section shell length becomes the main factor affecting the overall installation quality of the GIL.

[0129] The following factors should be considered when calculating (checking) the lengths of the compensation section shell and conductor:

[0130] (1) The influence of ambient temperature during installation. According to the previous calculation, the reference temperature of 22℃ is the turning point for thermal expansion and contraction of the shell and conductor. If the ambient temperature during installation is higher than this temperature, both the shell and conductor will thermally expand; if it is lower than this temperature, both the shell and conductor will contract. Therefore, the amount of thermal expansion and contraction of the shell and conductor must be calculated based on the ambient temperature during installation.

[0131] (2) The compensation section shell needs to compensate for the axial elongation of all shells above it (hereinafter referred to as the hoisting section shell) under their own weight. This elongation includes the axial elongation of the shell under its own weight when the bridge crane lifts the hoisting section shell, and the length reduction of the entire shell under its own weight after the hook is removed, the elastic deformation of the hoisting section shell disappears, and the shell is compressed under its own weight after the compensation section shell is reinstalled.

[0132] (3) Adjustment range of the universal joint at the top of the GIL. When the GIL is running, part of the current flowing through the conductor is consumed in the conductor resistance, which generates heat and raises the temperature of the GIL conductor, SF6 gas and shell, causing axial thermal expansion of the conductor and shell. The axial thermal expansion of the conductor is compensated by the axial gap between the conductor contact and the contact seat. The axial expansion of the shell must be compensated by the universal joint at the top of the GIL. Therefore, it is necessary to ensure that the axial elongation of the shell does not exceed the adjustment range of the universal joint when the GIL is running.

[0133] Step Nine: Calculation of axial thermal expansion and contraction of the housing caused by changes in ambient temperature during installation:

[0134] ΔL shell- Environment = α(t2-t1)L;

[0135] In the formula, α is the coefficient of linear expansion of aluminum alloy, 2.3 × 10⁻⁶. -6 ℃ -1 t2 is the ambient temperature at the time of installation, t1 is the reference temperature, i.e. the turning point temperature at which the shell undergoes thermal expansion and contraction, 22℃, and L represents the calculated length of the lower section of the GIL shell in shaft #3.

[0136] Step 10: Calculation of the axial elongation of the shell under its own weight when the bridge crane lifts the hoisting section shell:

[0137] The length of the lower section of shaft #3, L4A, refers to the calculated length of the lower section of the GIL shell in shaft #3 after excluding the penultimate and second-to-last sections below the GIL. The length of the hoisting section shell is as follows:

[0138] L 吊装段 =LL -2 -L -1 =216360-10600-8400=197360mm, where L -2 L -1 It refers to the lengths of the second-to-last and last sections of the casing below the GIL.

[0139] Lifting section mass: M 吊装段 =MM -2 -M -1 -M SF6 -M 绝缘子 ;

[0140] 11030.56-(10600+8400)×10-3×25.739-1616.052-(44.5+47.5)=8836.5kg.

[0141] Where M = 11030.56 kg, is the total mass of the 4A phase GIL; M -2 =10600×10⁻³×25.739kg, which is the mass of the second-to-last shell section; M -1 =8400×10⁻³×25.739 kg, which is the mass of the penultimate shell section; M SF6 =1616.052 kg, which is the mass of SF6 gas filled into the GIL; M 绝缘子 = (44.5 + 47.5) kg, which is the mass of the insulators installed in the second-to-last and last-to-last sections of the GIL casing. The top of the hoisting section casing is hung on the crane hook. Using ANSYS software, the axial elongation of the casing under its own weight during hoisting is calculated as follows:

[0142] △L 壳体自重拉伸 = 7.4513mm. See [link to details regarding shell load and constraint application method for hoisting section]. Figure 12 See the axial deformation cloud diagram of the shell. Figure 13 .

[0143] Step 11: Calculation of the length shortening of the lower section of the GIL in shaft #3 after the hook is removed, under its own weight and pressure:

[0144] After the compensation section shell, hoisting section shell, and penultimate section shell (i.e., fixed section shell) are welded together to form the lower section shell of shaft #3, the hook is removed. The entire shell section is fixed only at its lower end, like a column. At this point, it is only subject to the weight of the GIL itself, and the shell will undergo axial compressive deformation. The maximum axial compressive deformation of the GIL shell under its own weight is ΔL. 壳体自重压缩 = -8.955mm.

[0145] Step 12: Calculation of the axial elongation of the shell under GIL gravity that needs to be compensated for in the compensation section:

[0146] When determining the length of the compensation section shell, the axial expansion and contraction of the entire shell under its own weight in the lower section of shaft #3 must be considered:

[0147] ΔL weight =ΔL 壳体自重拉伸 +ΔL 壳体自重压缩 ;

[0148] The calculation is -8.955 + 7.4513 = -1.504 mm.

[0149] Step Thirteen: Determining the Length of the Compensation Section Shell:

[0150] Before welding the compensation section shell, all pipes above the compensation section pipeline are hoisted to their pre-disassembly installation positions using a 20t bridge crane on site. A laser rangefinder is then used to measure the required actual length L of the compensation section shell at this point. 实际 Based on this actual length, add the axial elongation ΔL of the shell under the gravity of the GIL that needs to be compensated. weight In addition, the axial thermal expansion and contraction ΔL of the housing caused by changes in ambient temperature during installation is also considered. shell-环境 That is, the final length of the compensation section shell:

[0151] L 补偿段 =L 实际 +ΔL weight +ΔL shell-环境 ;

[0152] If the ambient temperature during the installation of the compensation section housing is 35℃, then the axial thermal expansion and contraction of the housing caused by changes in ambient temperature during installation is as follows:

[0153] ΔL shell-环境 =α(t2-t1)L=2.3×10-6(35-22)×216360=6.469mm;

[0154] Note that the shell length L is the calculated length of the lower section of the GIL shell in shaft #3 (i.e., L = 216360 mm), which includes the length of the hoisting section, the length of the penultimate shell section, and the length of the final compensation section.

[0155] The axial expansion and contraction of the entire shell of the lower section of GIL in shaft #3 under its own gravity:

[0156] ΔL weightt =ΔL 壳体自重拉伸 +ΔL 壳体自重压缩 =-8.955+7.4513=-1.504mm;

[0157] The measured length of the outer shell of the compensation section pipe is L. 实际 The final length of the compensation section shell:

[0158] L 补偿段 =L 实际 +ΔL weightt +ΔL shell-环境 =L 实际 +(-1.504)+6.469=L 实际 +4.965mm.

[0159] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be defined as the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for calculating the length of a shaft GIL compensation section, characterized in that, Comprise: S1, determine the GIL bus compensation section length calculation parameters, including the installation of the ambient temperature thermal expansion and contraction, the axial elongation under the action of the shell itself gravity, the shell compression after the removal of the hoisting section; S2, calculate the deformation of the GIL bus shell under the section of the shaft, including: S201, calculate the shell axial thermal expansion and contraction caused by the change of ambient temperature during installation: ； In the formula, α is the linear expansion coefficient of the aluminum alloy material, T is the ambient temperature at the time of installation, T is the reference temperature, i.e., the turning temperature at which thermal expansion and cold contraction of the shell occur, and L represents the calculated length of the lower section GIL shell of the shaft. S202, calculate the axial elongation of all shells above the compensation section shell, that is, the hoisting section shell under the action of its own gravity, including calculating the axial elongation of the shell under the action of its own gravity when the hoisting section shell is lifted by the bridge crane, as follows: Calculating a hoisting shell length of a hoisting section shell : ； In the formula, represents the hoisting shell length of the hoisting section shell after all the shells below the hoisting section shell are removed; L represents the calculated length of the lower section GIL shell of the shaft; represents the sum of the lengths of all the shells below the hoisting section shell. Calculating hoist segment mass : ； wherein Mtotal represents the total mass of the lower shaft GIL, Mbottom represents the sum of the masses of all the casings below the hoisting section casing of the section, MSF6 represents the mass of the SF6 gas filled in the GIL, Minsulator represents the sum of the masses of the insulators installed in all the casings below the hoisting section casing of the section; The top end of the hoisting section shell is hung on the bridge machine lifting hook, and the hoisting shell length calculated above and the hoisting section mass The ANSYS software is input, the axial elongation of the hoisting section shell under the action of its own gravity is obtained through ANSYS software calculation ; S203, measure the shell compression after the removal of the hoisting section of the GIL, so as to calculate the axial elongation of the shell under the action of the GIL gravity which needs to be compensated by the compensation section; S3, calculate the length of the shell of the compensation section; S4, calculate the maximum deformation of the conductor, so as to design the length of the compensation section according to the deformation of the shell of the compensation section and the maximum deformation of the conductor.

2. The shaft GIL compensation segment length calculation method of claim 1, wherein, In step S203, after the hooks are removed, the whole shell is only fixed at the lower end, at this time, it is only subjected to the gravity of the GIL itself, the shell will be compressed and deformed in the axial direction, and the maximum axial compression deformation of the GIL shell under the action of the self weight is measured .

3. The shaft GIL compensation segment length calculation method of claim 2, wherein, In step S203, the axial elongation of the shell under the action of the GIL gravity which needs to be compensated by the compensation section shell is calculated as follows: ； In the formula, the positive value represents stretching, and the negative value represents contraction.

4. The shaft GIL compensation segment length calculation method of claim 3, wherein, In step S3, the length of the shell of the compensation section is calculated as follows: S301, measure the required actual length of the compensation section pipeline shell at this time using a laser range finder ; S302, calculate the final length of the compensation section shell: ； In the formula, The calculated length L of the lower shaft GIL housing is calculated by the length of the hoisting section, the length below the hoisting section, and the final compensation section length.

5. The shaft GIL compensation segment length calculation method of claim 1, wherein, In step S4, the deformation of the conductor is calculated as follows: ； In the formula, represents the axial deformation caused by the conductor gravity, which is calculated directly by inputting the measured conductor length into ANSYS software; represents the axial deformation caused by the conductor temperature rise, which is calculated by inputting the measured conductor length, the linear expansion coefficient of the aluminum alloy material, and the allowable temperature rise under the rated current of the conductor into ANSYS software.

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