Dry-type Air-core Light Bridge Arm Reactor Lifting Device and Its Design Method

Abstract

The present invention discloses a dry-type air-core light bridge arm reactor elevation device and its design method. It belongs to the technical field of the design and manufacture of dry-type air-core reactors. By establishing a three-dimensional model of the reactor elevation device, based on the side length and thickness of the top square plate, as well as the diameter and thickness of the bottom circular plate; taking the hot spot temperature rise as the objective function, using the combination of genetic algorithm and finite element simulation to perform multi-objective optimization on the middle structural parameters, and outputting the optimization results as the final design parameters. This application solves the problem of long design and development time caused by solely relying on multiple tests or simulation iterations. At the same time, based on the technical difficulties of the current dry-type air-core bridge arm reactor elevation device for offshore flexible DC transmission, such as poor fatigue resistance and high temperature rise, a structure of the elevation device with high reliability, low temperature rise, and good mechanical seismic resistance is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of the design and manufacture of dry-type air-core reactors, and particularly relates to a dry-type air-core light bridge arm reactor lifting device and a design method thereof for solving the problems of strength, fatigue and eddy current loss heating of the dry-type air-core light bridge arm reactor lifting device for flexible DC transmission of offshore wind power. Background Art

[0002] China is gradually building a new power system with new energy as the main body. Wind power is a key link and plays an increasingly important role. In the growing wind energy market and limited available onshore space, the total power generation and installed capacity of offshore wind farms are increasing year by year. From the perspective of economic benefits, offshore AC transmission systems are mostly applicable to transmission distances within 80 kilometers offshore. For longer distances, DC transmission must be used, and the deep sea has become the key area for the offshore wind power layout of various countries.

[0003] As an important device indispensable for ensuring the normal operation of the offshore wind power flexible DC system, the bridge arm reactor mainly plays the role of suppressing the circulating current between bridge arms and suppressing the fault current between bridge arms that rises too fast during short circuits. This device is generally fixed inside the offshore platform. Since the offshore platform reaches the ten-thousand-ton level, in order to reduce the installation and transportation difficulty of the entire platform, it is of great significance to develop lightweight and compact bridge arm reactors.

[0004] As a key component of the dry-type air-core light bridge arm reactor device, the lifting device mainly plays the role of transitional connection and reducing the temperature rise of the end flange of the post insulator. During the design process, it is necessary to consider the temperature rise problem, strength problem and fatigue problem of the lifting device itself. Different from conventional smoothing or shunt reactors, the current component of the bridge arm reactor is a composite of AC and DC, and the reactor lifting device will generate a large temperature rise under the action of the leakage magnetic field. In addition, since the dry-type air-core light bridge arm reactor is installed inside the offshore platform, under the impact of sea waves, the platform and the internal power equipment vibrate. In addition to meeting the strength requirements of the equipment, the lifting device should also minimize the stress concentration area as much as possible to avoid fatigue failure.

[0005] In summary, the existing disclosed design methods and structures of dry-type air-core bridge arm reactor lifting devices cannot quickly meet the design and development requirements of dry-type air-core light bridge arm reactors for large-capacity offshore flexible DC converter stations. Summary of the Invention

[0006] Therefore, the purpose of the present invention is to provide a dry-type air-core light bridge arm reactor lifting device and a design method thereof, which improve the previous development method of the lifting device that simply relies on design experience, propose a positive design calculation method, and reduce the problem of long design and development time caused by simply relying on multiple tests or simulation iterations.

[0007] To achieve the above object, a design method for a lifting device of a dry-type air-core light bridge arm reactor provided by the present invention includes the following steps:

[0008] S1. Generate the structural composition information and material parameter information of the reactor lifting device. The structural composition information of the lifting device includes a top square plate, a middle structure, and a bottom circular plate. The middle structure includes a hollow cylinder and stiffening plates arranged around the hollow cylinder. The top of the hollow cylinder and the stiffening plates is connected to the top square plate, and the bottom of the hollow cylinder and the stiffening plates is connected to the bottom circular plate.

[0009] S2. Determine the side length, thickness of the top square plate, and the diameter and thickness of the bottom circular plate according to the structural information of the star frame arm fixing plate and the upper flange of the post insulator of the dry-type air-core reactor. S3. Use the genetic algorithm to perform multi-objective optimization on the middle structure parameters, including:

[0010] Take the outer diameter and wall thickness of the hollow cylinder, the height and thickness of the stiffening plate as the design variable X;

[0011] Establish the objective function with unchanged strain energy and the lowest hot spot temperature rise: min T(X)=K

[0012]

[0013] In the formula, X—design variable; K—hot spot temperature rise; C—structural strain energy; —lower limit of the design variable; —upper limit of the design variable; J—strain energy constraint value calculated based on the target stiffness limit condition;

[0014] Use the structural composition information and material parameter information generated in S1 and the parameters determined in S2 to perform finite element simulation, calculate the structural strain energy and hot spot temperature rise value, and through the genetic algorithm, change the values of each design variable, and judge whether the objective function obtains the minimum value. When the minimum value is obtained and the population data converges, output the optimization result as the final design parameter.

[0015] Further preferably, in S2, when determining the side length, thickness of the top square plate, and the diameter and thickness of the bottom circular plate according to the installation requirements and material characteristics, it includes:

[0016] Set the side length dimension of the top square plate W Not greater than the side length of the structural bottom plate of the fixed star frame arm mounting plate in the reactor support system;

[0017] The diameter of the bottom circular plate is not greater than the diameter dimension of the upper flange of the post insulator;

[0018] The thickness of the top square plate and the bottom circular plate is calculated according to the following formula:

[0019]

[0020] Among them, is the tensile design value of the structural material; is the bending moment in the plate.

[0021] Furthermore, preferably, the bending moment in the plate is calculated using the following formula

[0022]

[0023] Among them, is the bending moment coefficient and q is the equivalent uniform load on the plate; lx is the dimension of the stress-bearing area of the flange plate.

[0024] Furthermore, preferably, the equivalent uniform load on the plate is calculated using the following formula:

[0025]

[0026] In the formula, lx, ly are respectively the characteristic dimensions of the stress-bearing area of the flange plate; is the maximum tensile force of the flange bolt.

[0027] Furthermore preferably, the maximum tensile force of the flange bolt is calculated using the following formula:

[0028]

[0029] In the formula, M is the bending moment on the flange, N·mm; N is the axial force on the flange, negative value is taken for pressure, N; is the number of bolts corresponding to the plate; is the distance from the bolt center to the rotation axis, is the distance from the bolt center with the maximum force to the rotation axis, mm.

[0030] Furthermore preferably, it also includes dividing the profile of the stiffening plate along the height direction into a straight segment and a curved segment, where the curvature of the curved segment arc is calculated according to the following formula:

[0031]

[0032] Among them, H is the total height of the middle structure of the lifting device, is the height of the straight segment of the stiffening plate, is the step height of the stiffening plate; is the curvature control parameter; x is the horizontal length coordinate value of the curved segment from the outermost side at the bottom of the stiffening plate, is the side length of the top of the stiffening plate; is the side length of the bottom of the stiffening plate.

[0033] The present invention also provides a lifting device for a dry-type air-core light bridge arm reactor, which is designed based on the steps of the design method of the above dry-type air-core light bridge arm reactor lifting device, and includes a top square plate, a middle structure and a bottom circular plate; the middle structure includes a hollow cylinder and stiffening plates arranged around the hollow cylinder;

[0034] Further preferably, there are 4 stiffening plates, which are evenly distributed around the hollow cylinder.

[0035] Further preferably, the side of the hollow cylinder is provided with a slot, and the width of the slot is 5 mm.

[0036] Further preferably, the end of the stiffening plate is provided with a step. When the thickness of the stiffening plate is less than 6 mm, the step height is 10 mm; when the thickness of the stiffening plate is 6 mm - 12 mm, the step height is 15 mm; when the thickness of the stiffening plate is greater than 12 mm, the step height is 20 mm.

[0037] The dry-type air-core light bridge arm reactor lifting device and its design method disclosed in the present application reduce the problem of long design and development time caused by simply relying on multiple tests or simulation iterations. At the same time, it solves the technical difficulties of poor fatigue resistance and high temperature rise of the current dry-type air-core bridge arm reactor lifting device for HVDC light transmission at sea; by optimizing the structure of the annular hollow cylinder, the eddy current loss heating is reduced, and by improving the contour of the stiffening plate, the stress distribution is improved, and the seismic mechanical performance is enhanced, ensuring that the lifting device can meet the reliability application of the AC-DC composite action and long-period sea wave excitation conditions, and improving the safety and reliability of the bridge arm reactor support system. Description of the Drawings

[0038] Figure 1 is a schematic diagram of the designed lifting device in the reactor support system of the present invention.

[0039] Figure 2 is a schematic structural diagram of the designed lifting device of the present invention.

[0040] Figure 3 is the force-bearing area of the flange plate connected to the lifting device in the present invention.

[0041] Figure 4 is a schematic diagram of the force on the flange bolts in the present invention.

[0042] Figure 5 is a flow chart of the design method of the dry-type air-core light bridge arm reactor lifting device disclosed in the present invention.

[0043] Figure 6Schematic diagram of the annular hollow cylinder structure in the lifting device.

[0044] Figure 7 Schematic diagram of the stiffening plate structure in the lifting device. Detailed implementation manners

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0046] As Figure 1 shown, in order to connect the upper part of the lifting device A to the star frame arm mounting plate B and the lower part of the lifting device to the upper flange of the post insulator C, the top structure of the lifting device is generally designed as a square plate, and the bottom structure is designed as a circular plate. To further reduce the heat generation due to eddy current loss in the lifting device, the side length of the top square plate is not greater than the side length of the bottom plate of the fixed star frame arm mounting plate structure in the reactor support system, and the diameter of the bottom circular plate is not greater than the diameter of the upper flange of the post insulator.

[0047] As Figure 2 shown, the dry-type air-core light bridge arm reactor lifting device provided by an embodiment of the present invention on the one hand is designed based on the steps of the design method of the dry-type air-core light bridge arm reactor lifting device, and includes a top square plate 1, a middle structure, and a bottom circular plate 4; the middle structure includes a hollow cylinder 3 and stiffening plates 2 arranged around the hollow cylinder. The structural material is stainless steel.

[0048] To reduce the heat generation due to eddy current loss, the annular hollow cylinder structure is grooved, and the groove width is 5 mm. Four stiffening plates are arranged circumferentially along the annular hollow cylinder.

[0049] Considering that acute angles are prone to stress concentration, cracking is likely to occur under cyclic loading conditions, and fillet welding at acute angles is difficult to achieve. Therefore, a step design is carried out at the end of the stiffening plate, and the step height ( ) should be greater than the weld height in the design. The selection principle can be referred to as follows:

[0050] When the thickness of the stiffening plate is less than 6 mm, the step height is taken as 10 mm;

[0051] When the thickness of the stiffening plate is 6 mm - 12 mm, the step height is taken as 15 mm;

[0052] When the thickness of the stiffening plate is greater than 12 mm, the step height is taken as 20 mm.

[0053] To avoid the two-way tensile stress condition that may occur when the main weld and the rib plate weld cross, improve the plasticity at the joint, and avoid the occurrence of brittle cracks, at the inner corner of the stiffening plate, such as Figure 7 the P1 point shown, the inner corner of the top of the rib plate is cut off to improve the stress state.

[0054] As Figure 5As shown, in accordance with the following steps: start - parametric model of the middle structure of the lifting device - prepare material parameters for mechanical simulation and thermal simulation - determine calculation conditions - lengths of the upper and lower bases of the stiffening plate - pre - processing - simulation calculation - post - processing - objective: minimum hot - spot temperature rise; constraint condition: constant strain energy; whether the iteration converges - yes, end / no, change design variables - return to the pre - processing step.

[0055] Specifically, a design method for a lifting device of a dry - type air - core light - type bridge - arm reactor provided by the present invention includes the following steps:

[0056] S1. Generate the structural composition information and material parameter information of the reactor lifting device. The structural composition information of the lifting device includes a top square plate, a middle structure, and a bottom circular plate. The middle structure includes a hollow cylinder and stiffening plates arranged around the hollow cylinder. The top of the hollow cylinder and the stiffening plates is connected to the top square plate, and the bottom of the hollow cylinder and the stiffening plates is connected to the bottom circular plate.

[0057] S2. Determine the side length, thickness of the top square plate, and the diameter and thickness of the bottom circular plate according to the structural information of the star - shaped frame arm fixing plate and the upper flange of the post insulator of the dry - type air - core reactor. Further preferably, in S2, when determining the side length, thickness of the top square plate, and the diameter and thickness of the bottom circular plate according to the structural information of the star - shaped frame arm fixing plate and the upper flange of the post insulator of the dry - type air - core reactor, it includes:

[0058] Set the side - length dimension of the top square plate W not greater than the side length of the structural bottom plate of the fixed star - shaped frame arm mounting plate in the reactor support system;

[0059] The diameter of the bottom circular plate is not greater than the diameter dimension of the upper flange of the post insulator;

[0060] The thicknesses of the top square plate and the bottom circular plate are calculated according to the following formula:

[0061]

[0062] where, is the tensile design value of the structural material; is the bending moment in the plate.

[0063] Further preferably, the bending moment in the plate

[0064]

[0065] where, is the bending - moment coefficient and q is the equivalent uniform load on the plate; lx is the dimension of the stress - bearing area of the flange plate. The bending - moment coefficient can be obtained from Table 1 as follows.

[0066] Table 1 Bending moment coefficient

[0067]

[0068] As Figure 3 shown, the equivalent uniform load on the plate is calculated by the following formula:

[0069]

[0070] In the formula, lx, ly are the characteristic dimensions of the stress area of the flange plate respectively; is the maximum tensile force of the flange bolt.

[0071] Furthermore, as Figure 4 shown, the maximum tensile force of the flange bolt is calculated by the following formula:

[0072]

[0073] In the formula, M is the bending moment on the flange, N·mm; N is the axial force on the flange, and the pressure is taken as a negative value, N; is the number of bolts corresponding to the plate; is the distance from the bolt center to the rotation axis, is the distance from the bolt center with the maximum stress to the rotation axis, mm.

[0074] S3. Use the genetic algorithm to perform multi-objective optimization on the middle structure parameters, including:

[0075] S301. Based on the structure information of S1, take the outer diameter and wall thickness of the hollow cylinder, and the width and thickness of the stiffening plate as the design variables X; the design variables of the annular hollow cylinder mainly include the outer diameter and the wall thickness . The design variables of the stiffening plate mainly include the width of the stiffening plate and the thickness of the stiffening plate. As Figure 6 shown.

[0076] S302. Determine the constraint conditions

[0077] Comprehensively consider the design requirements and actual needs, and combine the influence analysis of the dimensional parameters on the strength and temperature rise to limit the values of the design variables X , set its lower limit as , and the upper limit . The overall stiffness of the model after size optimization should be ensured not to decrease, so the strain energy C。

[0078] S303. Establish the objective function based on the invariant strain energy and the lowest hot spot temperature rise: min T(X) = K

[0079]

[0080] In the formula, X is the design variable; K is the hot spot temperature rise; C is the structural strain energy; —Lower limit of the design variable; —Upper limit of the design variable; J is the strain energy constraint value calculated based on the target stiffness constraint condition

[0081] Using the structural composition information and material parameter information generated by S1 and the parameters determined in S2, perform finite element simulation, calculate the strain energy and hot spot temperature rise value of the structure. Through the genetic algorithm, change the values of each design variable, and judge whether the objective function obtains the minimum value. When the minimum value is obtained and the population data converges, output the optimization result as the final design parameter.

[0082] Through the genetic algorithm, change the values of each design variable, judge whether the constraint conditions are satisfied and whether the design goal is achieved. If the optimization is not completed, repeat the above process; if the optimization is completed, output the optimization result. Use whether the population data generated in the iterative process converges as the criterion for the completion of the optimization.

[0083] Further preferably, as Figure 7 shown, it also includes dividing the profile of the stiffening plate along the height direction into a straight line segment and a curve segment. Among them, the curvature of the arc of the curve segment is calculated according to the following formula:

[0084]

[0085] Among them, H is the total height of the middle structure of the lifting device, is the height of the straight line segment of the stiffening plate, is the step height of the stiffening plate; is the curvature control parameter; x is the horizontal length coordinate value of the curve segment from the outermost side of the bottom of the stiffening plate ， is the side length of the top of the stiffening plate; is the side length of the bottom of the stiffening plate.

[0086] By optimizing the structure of the annular hollow cylinder, reduce the eddy current loss heating. By improving the profile of the stiffening plate, improve the stress distribution, enhance the seismic mechanical properties, ensure that the lifting device can meet the reliability application of the AC-DC composite action and long-period sea wave excitation conditions, and improve the safety and reliability of the bridge arm reactor support system.

[0087] Obviously, the above embodiments are only examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or variations derived therefrom still fall within the protection scope of the present invention.

Claims

1. A design method for a dry-type hollow light bridge arm reactor elevation device, characterized in that: The following steps are involved: S1. Generate structural composition information and material parameter information of the reactor lifting device, wherein the structural composition information of the lifting device includes a top square plate, a middle structure and a bottom circular plate; the middle structure includes a hollow cylinder and a stiffening plate arranged around the hollow cylinder; the top of the hollow cylinder and the stiffening plate are connected to the top square plate, and the bottom of the hollow cylinder and the stiffening plate are connected to the bottom circular plate; S2. Determine the side length and thickness of the top square plate and the diameter and thickness of the bottom circular plate according to the structural information of the star frame arm fixing plate and the flange on the post insulator of the dry-type air-core reactor; the side length of the top square plate shall not be greater than the side length of the bottom plate of the star frame arm mounting plate structure, and the diameter of the bottom circular plate shall not be greater than the diameter of the flange on the post insulator; S3. Use genetic algorithm to perform multi-objective optimization on the parameters of the middle structure, including: The outer diameter and wall thickness of the hollow cylinder, and the width and thickness of the stiffening plate are taken as the design variables X; The objective function is established with the strain energy unchanged and the hot spot temperature rise as minimum: min T (X) = K In the formula, X is the design variable; K is the hot spot temperature rise; C is the structural strain energy; —Lower limit of design variables; —Upper limit of design variables; J—strain energy constraint value calculated based on target stiffness constraint conditions; Finite element simulation is performed using the structural composition information and material parameter information generated by S1 and the dimensional parameters determined in S2 to calculate the strain energy and hot spot temperature rise of the structure. The genetic algorithm is used to change the values ​​of each design variable to determine whether the objective function has achieved the minimum value. When the minimum value is achieved and the population data converges, the optimization result is output as the final design parameter.

2. The design method of the dry-type hollow light bridge arm reactor elevation device according to claim 1 is characterized in that: In S2, the step of determining the side length and thickness of the top square plate and the diameter and thickness of the bottom circular plate according to the structural information of the star frame arm fixing plate and the upper flange of the post insulator of the dry-type air-core reactor includes: The thickness of the top square plate and the bottom circular plate is calculated as follows: in, is the tensile design value of the structural material; is the bending moment in the plate.

3. The design method of the dry-type hollow light bridge arm reactor elevation device according to claim 2 is characterized in that: The bending moment in the plate is calculated using the following formula: in, is the bending moment coefficient, q is the equivalent uniformly distributed load on the plate; lx is the size of the stress-bearing area of ​​the flange plate.

4. The design method of the dry-type hollow light bridge arm reactor elevation device according to claim 3 is characterized in that: The equivalent uniformly distributed load on the plate is calculated using the following formula: In the formula, lx、ly are the characteristic dimensions of the stress-bearing area of ​​the flange plate; is the maximum tension of the flange bolts.

5. The design method of the dry-type hollow light bridge arm reactor elevation device according to claim 4 is characterized in that: The maximum tension of the flange bolts The calculation is done using the following formula: In the formula, M is the bending moment of the flange, N·mm; N is the axial force acting on the flange, the pressure is taken as a negative value, N; is the number of bolts on the corresponding plate; is the distance from the bolt center to the rotation axis, is the distance from the center of the bolt with maximum force to the rotation axis, mm.

6. The design method of the dry-type hollow light bridge arm reactor elevation device according to claim 1 is characterized in that , and also includes dividing the stiffening plate profile into straight segments and curved segments along the height direction, wherein the curvature of the curved segment arc is calculated according to the following formula: in, H To increase the overall height of the middle structure of the device, is the height of the straight section of the stiffener, is the height of the stiffening plate step; is the curvature control parameter; x is the horizontal length coordinate value of the curve segment from the outermost side of the bottom of the stiffening plate; is the length of the top side of the stiffening plate; is the bottom side length of the stiffener.

7. A dry-type hollow light bridge arm reactor lifting device, characterized in that: The dry-type hollow light-weight bridge arm reactor lifting device is manufactured based on the steps of the design method of any one of claims 1 to 6, and includes a top square plate, a middle structure and a bottom circular plate; the middle structure includes a hollow cylinder and a stiffening plate arranged around the hollow cylinder, the top of the hollow cylinder and the stiffening plate are connected to the top square plate, and the bottom of the hollow cylinder and the stiffening plate are connected to the bottom circular plate.

8. The dry-type hollow light bridge arm reactor raising device according to claim 7, characterized in that: There are four stiffening plates evenly distributed around the hollow cylinder.

9. The dry-type hollow light bridge arm reactor raising device according to claim 7, characterized in that: The side of the hollow cylinder is provided with a slot, and the slot width is 5mm.

10. The dry-type hollow light bridge arm reactor raising device according to claim 7, characterized in that: The end of the stiffening plate is provided with a step, When the thickness of the stiffening plate is less than 6mm, the step height is 10mm; When the thickness of the stiffening plate is 6mm-12mm, the step height is 15mm; When the thickness of the stiffening plate is greater than 12mm, the step height is 20mm.

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