Transformer oil tank wall

Abstract

The invention provides a transformer oil tank wall. The transformer oil tank wall comprises an inner-layer tank wall and an outer-layer tank wall, the outer-layer tank wall is arranged outside the inner-side tank wall in the length direction of the oil tank, a buffering energy-absorbing cavity is defined between the outer-layer tank wall and the inner-side tank wall, the buffering energy-absorbing cavity is filled with buffering energy-absorbing materials, and rib plates are further arranged in the buffering energy-absorbing cavity; the upper box edge and the lower box edge are arranged at the top end and the bottom end of the inner-layer box wall respectively, and supporting reinforcing ribs are arranged between the upper box edge and the top of the outer-layer box wall and between the lower box edge and the bottom of the outer-layer box wall respectively. The outer-layer tank wall is arranged outside the inner-layer tank wall to form the composite tank wall, the rib plates and the buffer energy-absorbing materials are arranged between the outer-layer tank wall and the inner-layer tank wall, and the supporting reinforcing ribs are arranged among the upper tank edge, the lower tank edge and the inner-layer tank wall, so that the transformer oil tank wall forms a rigid-flexible composite supporting network, and a rigid-flexible anti-impact protection mechanism is achieved; and therefore, the static pressure strength and the dynamic impact resistance are synergistically improved.

Description

Technical Field

[0001] The invention relates to the technical field of electric power equipment, and in particular to a transformer oil tank wall. Background Art

[0002] The design of the traditional UHV transformer tank wall mainly focuses on meeting the static pressure strength requirements (such as positive pressure 120kPa, negative pressure 13Pa), usually using a single thickened steel plate or adding a local rigid support structure. However, under extreme conditions such as internal high-energy arc faults, the instantaneous shock wave will form a high-intensity mechanical stress field on the surface of the tank wall, resulting in local stress concentration on the inner wall, which is very likely to cause cracks or even ruptures, causing serious accidents such as insulating oil leakage and fire. In the existing technology, although simply increasing the thickness of the tank wall can improve the static pressure bearing capacity, it will significantly reduce the plastic deformation space of the material and weaken the energy absorption efficiency; while the dense arrangement of rigid support structures may cause the overall "over-rigidity" of the tank wall, which will aggravate the stress transfer due to the lack of a buffer mechanism under dynamic impact, and increase the risk of rupture. In addition, the traditional design has not been adapted and optimized for the differentiated load characteristics of road and rail transportation, and is prone to structural fatigue or installation conflicts due to vibration or size restrictions. Summary of the invention

[0003] In view of this, the present invention proposes a transformer oil tank wall, aiming to solve the problem that the static pressure strength and dynamic impact resistance of the existing oil tank wall are difficult to coordinately optimize.

[0004] The present invention proposes a transformer oil tank wall, which includes: an inner tank wall; an outer tank wall, which is arranged outside the inner tank wall along the length direction of the oil tank, and a buffer energy absorption cavity is formed between the outer tank wall and the inner tank wall, and the buffer energy absorption cavity is filled with buffer energy absorption material, and a rib plate is also provided in the buffer energy absorption cavity to provide local rigidity support; an upper tank edge and a lower tank edge, which are respectively arranged at the top and bottom ends of the inner tank wall, and support reinforcement ribs are respectively provided between the upper tank edge and the lower tank edge and the top and bottom of the outer tank wall, so that the support reinforcement ribs, the rib plate and the outer tank wall form a rigid support network to suppress stress diffusion.

[0005] Furthermore, for the above-mentioned transformer oil tank wall, the finite element model of the transformer oil tank wall is optimized for distribution to obtain optimized design parameters that meet the constraint conditions; wherein, the constraint conditions include: static pressure deformation constraint conditions and dynamic impact constraint conditions; the optimized design parameters include: the thickness of the buffer energy-absorbing material, the yield strength of the buffer energy-absorbing material, and the number of rib plates; the static pressure deformation constraint condition is that the deformation of the transformer oil tank wall under a positive pressure of 120 kPa and a negative pressure of 13 Pa is less than or equal to 3 times the thickness of the inner layer tank wall; the dynamic impact constraint condition is that when the inner layer tank wall is subjected to an 80 MJ arc fault energy impact, the ratio of its material dynamic ultimate strain to plastic working strain should be greater than or equal to k; wherein, when the voltage level exceeds 800 kV, k > 1.4; when the voltage level exceeds 1000 kV, k > 1.5.

[0006] Furthermore, for the above-mentioned transformer oil tank wall, the outer layer tank wall is a cuboid shell structure with one end open, and its four side plates are connected to the inner layer tank wall.

[0007] Furthermore, for the above-mentioned transformer oil tank wall, the buffer energy-absorbing material is installed in the buffer energy-absorbing cavity through an interference filling process, or the buffer energy-absorbing material is adhesively connected to the inner wall of the buffer energy-absorbing cavity.

[0008] Furthermore, for the above-mentioned transformer oil tank wall, the inner layer tank wall is made of Mn13 plastic steel, and its yield strength ≥ 300 MPa.

[0009] Furthermore, for the above-mentioned transformer oil tank wall, the outer layer tank wall is made of Q345B steel, and its yield strength ≥ 400 MPa.

[0010] Furthermore, for the above-mentioned transformer oil tank wall, the part of the inner layer tank wall exposed outside the buffer energy-absorbing cavity and the outer wall of the outer side tank wall are provided with outer wall reinforcing ribs.

[0011] Furthermore, for the above-mentioned transformer oil tank wall, the inner layer tank wall is made by welding multiple modules, and the welds of the inner layer tank wall are arranged in the vertical direction, and each weld is within the coverage range of the buffer energy-absorbing material.

[0012] Furthermore, for the above-mentioned transformer oil tank wall, the cross-section of the support reinforcing rib is trapezoidal or rectangular.

[0013] Furthermore, for the above-mentioned transformer oil tank wall, the outer layer tank wall is connected to the inner layer tank wall by welding or by bolted butt joint.

[0014] The transformer tank wall provided by the present invention forms a composite tank wall by arranging an outer tank wall outside the inner tank wall, and arranging rib plates and buffer energy-absorbing materials between the two. Through the support reinforcing ribs arranged between the upper tank edge, the lower tank edge and the inner tank wall, the transformer tank wall forms a rigid-flexible composite support network, realizing an impact protection mechanism of "combining rigidity and flexibility", and further realizing the synergistic improvement of static pressure strength and dynamic impact resistance performance, solving the problem that it is difficult to synergistically optimize the static pressure strength and dynamic impact resistance performance of the existing tank wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 is a top view of the transformer tank wall provided by an embodiment of the present invention; Figure 2 is a side view of the transformer tank wall provided by an embodiment of the present invention; Figure 3 is a structural schematic diagram of the transformer tank wall for road transportation provided by an embodiment of the present invention; Figure 4 is a structural schematic diagram of the transformer tank wall for railway transportation provided by an embodiment of the present invention; Description of reference numerals: 1 - inner tank wall, 2 - outer tank wall, 3 - rib plate, 4 - buffer energy-absorbing material, 5 - upper tank edge, 6 - lower tank edge, 7 - support reinforcing rib, 8 - outer wall reinforcing rib. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0017] See Figures 1 to 4 , which shows the preferred structure of the transformer tank wall provided by an embodiment of the present invention. As shown in the figure, the transformer tank wall includes: an inner tank wall 1, an outer tank wall 2, rib plates 3, buffer energy-absorbing materials 4, an upper tank edge 5, a lower tank edge 6, support reinforcing ribs 7 and outer wall reinforcing ribs 8.

[0018] The outer box wall 2 is arranged outside the inner box wall 1 along the length direction of the fuel tank. A buffer and energy absorption cavity is formed between the outer box wall 2 and the inner box wall 1. The buffer and energy absorption cavity is filled with a buffer and energy absorption material 4. Moreover, rib plates 3 are arranged in the buffer and energy absorption cavity to provide local stiffness support.

[0019] Specifically, the inner box wall 1 can be made of steel with excellent plasticity, such as Mn13 plastic steel. The thickness of the inner box wall 1 can be reduced by 1-2 mm compared with the traditional design, and part of the impact energy can be absorbed through controllable deformation. Among them, the yield strength, i.e., the tensile strength, of the inner box wall 1 is greater than or equal to 300 MPa. The outer box wall 2 is arranged in the high-fault-risk area along the long axis direction of the fuel tank. The outer box wall 2 can be made of Q345B steel with a relatively high yield strength, and its yield strength, i.e., the tensile strength, is greater than or equal to 400 MPa. The outer box wall 2 can be a cuboid shell structure with one end open. Its four side plates are connected to the inner box wall 1, and a cuboid buffer and energy absorption cavity can be formed. The buffer and energy absorption material 4 is filled between the inner box wall 1 and the outer box wall 2 in the buffer and energy absorption cavity. The buffer and energy absorption material 4 is fixed between the inner box wall 1 and the outer box wall 2 through interference connection or bonding, that is, the buffer and energy absorption material 4 is installed in the buffer and energy absorption cavity through an interference filling process, or the buffer and energy absorption material 4 is adhesively connected to the inner wall of the buffer and energy absorption cavity. The elastic modulus and yield strength of the buffer and energy absorption material 4 are selected through simulation optimization to ensure controllable deformation in the static pressure stage and efficient energy consumption in the dynamic impact stage. Among them, the elastic modulus of the buffer and energy absorption material 4 can be 1-5 GPa, and the yield strength can be 1-20 MPa. The rib plates 3 can be evenly welded between the inner box wall 1 and the outer box wall 2. The number of rib plates 3 can be 8-15 to provide local stiffness support.

[0020] The upper box edge 5 and the lower box edge 6 are respectively arranged at the top and bottom of the inner box wall 1. Moreover, support and strengthening ribs 7 are respectively arranged between the upper box edge 5, the lower box edge 6 and the top and bottom of the outer box wall 2. Specifically, the upper box edge 5 is arranged between the inner box wall 1 and the box cover to realize the connection between the two; the lower box edge 6 is arranged between the inner box wall 1 and the box bottom plate to realize the connection between the two. Support and strengthening ribs 7 are also arranged between the upper box edge 5 and the top of the inner box wall 1, and between the lower box edge 6 and the bottom of the inner box wall 1, that is, the support and strengthening ribs 7 connect the outer box wall 2 with the upper and lower box edges. The cross-section is trapezoidal or rectangular to further optimize the bending resistance performance and improve the connection stability. The support and strengthening ribs 7 can be arranged circumferentially around the inner box wall 1 for a whole week, or can also be arranged in the risk area. The spacing of the inner box wall 1 is 200-500 mm to improve the overall bending resistance performance. Further preferably, the spacing of the support and strengthening ribs 7 can be 300 mm to improve the overall stiffness.

[0021] In this embodiment, to further improve the stability of the transformer oil tank wall, preferably, outer wall reinforcing ribs 8 are provided on the part of the inner tank wall 1 exposed outside the buffer energy absorption cavity and on the outer wall of the outer side tank wall 2. The outer wall reinforcing ribs 8, the rib plates 3 and the outer layer tank wall 2 form a rigid support network to inhibit stress diffusion, and in combination with the buffer energy absorption material 4, form a rigid-flexible composite support network. Specifically, the outer wall reinforcing rib 8 is a box-shaped structure with a hollow interior and an open side, and its cross-section can be a rectangular or trapezoidal structure. It can be fixedly installed on the part of the inner tank wall 1 exposed outside the buffer energy absorption cavity and on the outer wall of the outer side tank wall 2 by welding. Among them, the layout spacing of the outer wall reinforcing ribs 8 can be determined according to the actual situation.

[0022] In this embodiment, the inner layer tank wall 1 is fabricated by welding multiple modules, and the weld seams of the inner layer tank wall 1 are arranged in the vertical direction, and each of the weld seams is located within the coverage range of the buffer energy absorption material 4. Specifically, when welding the inner layer tank wall 1, vertical weld seams are used to avoid weld seam intersections or arrangements in the corner areas of the tank wall. All weld seams are located within the coverage range of the buffer energy absorption material 4 to reduce the risk of stress concentration. Among them, the inner layer tank wall 1 can be welded by TIG welding, i.e., tungsten inert gas welding, and the qualified rate of weld seam flaw detection is ≥99.5%.

[0023] In this embodiment, the finite element model of the transformer oil tank wall is optimized for distribution to obtain optimized design parameters that meet the constraint conditions; among them, the constraint conditions include: static pressure deformation constraint conditions and dynamic impact constraint conditions; the optimized design parameters include: the thickness of the buffer energy absorption material, the yield strength of the buffer energy absorption material, the number of rib plates; the static pressure deformation constraint condition is that the deformation of the transformer oil tank wall under a positive pressure of 120 kPa and a negative pressure of 13 Pa is less than or equal to 3 times the thickness of the inner layer tank wall; the dynamic impact constraint condition is that when the inner layer tank wall withstands an 80 MJ arc fault energy impact, the ratio of its material dynamic ultimate strain to plastic working strain should be greater than or equal to k; among them, when the voltage level exceeds 800 kV, k > 1.4; when the voltage level exceeds 1000 kV, k > 1.5.

[0024] Specifically, to optimize the distribution of the finite element model of the transformer oil tank wall, the ansys finite element simulation software can be used to establish a static simulation model and an explosion shock dynamic simulation model respectively, and optimize the structural parameters, so that the static pressure deformation and dynamic strain meet the constraint conditions. When establishing the static simulation model, the following static pressure deformation constraint equation is established based on finite element simulation:; where is the thickness of the inner layer tank wall 1, is the deformation of the transformer oil tank wall under a positive pressure of 120 kPa and a negative pressure of 13 Pa. When establishing the explosion shock dynamic simulation model, a dynamic impact plastic strain constraint equation is established: ; wherein, is the plastic strain of the inner tank wall under 80 MJ arc fault energy, the material limit value, which can be the safety factor value. When the voltage level exceeds 800 kV, k > 1.4; when the voltage level exceeds 1000 kV, k > 1.5. During optimization, the number of rib plates, thickness, thickness and yield strength of the buffer energy-absorbing material are used as variables, and the optimal parameter combination is determined through iterative simulation.

[0025] The following will respectively elaborate on the road transport fuel tank and the railway transport fuel tank in detail.

[0026] The road transport fuel tank can include: the inner tank wall 1, the outer tank wall 2, the rib plates 3, the buffer energy-absorbing material 4, the upper tank edge 5, the lower tank edge 6, the support reinforcing ribs 7 and the outer wall reinforcing ribs 8. The inner tank wall 1, the outer tank wall 2, the rib plates 3, the buffer energy-absorbing material 4 and the outer wall reinforcing ribs 8 are combined to form a rigid-flexible composite support network. The support reinforcing ribs 7 are arranged between the upper tank edge 5, the lower tank edge 6 and the inner tank wall 1, and the bending resistance performance is optimized through trapezoidal or rectangular cross-section design. The inner tank wall 1 is made of Mn13 plastic steel with a thickness of 10 mm, which is 2 mm less than the traditional design. When the inner tank wall 1 is butt-welded, vertical welds are used, and the welds avoid the corner areas and are all within the coverage of the buffer energy-absorbing material 4. The outer tank wall 2 is arranged in the high-fault-risk area along the long axis direction of the fuel tank, made of Q345B steel with a thickness of 12 mm, and is connected to the inner tank wall 1 through full penetration welding. The outer wall reinforcing ribs 8 connect the outer tank wall 2 with the upper tank edge 5 and the lower tank edge 6, with a rectangular cross-section and a spacing of 300 mm, to improve the overall stiffness. Distribution optimization parameters can be carried out for the road transport fuel tank. In the static pressure stage, the constraint is that the deformation amount under a positive pressure of 120 kPa and a negative pressure of 13 Pa is ≤ 3 times the inner wall thickness, and the number, thickness of the rib plates and the parameters of the buffer material are determined through finite element simulation; in the dynamic impact stage, the goal is that the plastic strain of the inner wall under 80 MJ arc fault energy is ≤ 0.8 times the material limit value, and the yield strength of the buffer material and the rib plate distribution are optimized. The buffer energy-absorbing material 4 is filled between the inner and outer tank walls with a thickness of 200 mm, made of aluminum foam material with an elastic modulus of 5 GPa and a yield strength of 10 MPa, and is fixed through interference fit. The rib plates 3 are evenly welded between the inner tank wall 1 and the outer tank wall 2, with 8 in number, a thickness of 10 mm and a spacing of 600 mm. Among them, the butt-welding of the inner tank wall 1 uses TIG welding, and the qualified rate of weld inspection is ≥ 99.5%. The welding of the outer tank wall 2 is completed before transportation to ensure the overall structural sealing and anti-fatigue performance.

[0027] The railway transportation fuel tank may include: an inner tank wall 1, an outer tank wall 2, rib plates 3, buffer energy-absorbing materials 4, an upper tank edge 5, a lower tank edge 6, support and strengthening ribs 7, and outer wall strengthening ribs 8. The inner tank wall 1 is made of Mn13 plastic steel with a thickness of 10 mm, which is 2 mm less than the traditional design. When the inner tank wall 1 is butt-welded, vertical welds are used, and the welds avoid the corner areas and are all within the coverage of the buffer energy-absorbing material 4. The outer tank wall 2 is connected to the inner tank wall 1 by means of bolted overlap joints. The bolts are M20 high-strength anti-loosening bolts with a pre-tightening force of 80 kN and a spacing of 150 mm. The outer tank wall is made of Q345B steel with a relatively high yield strength. The number of the outer wall strengthening ribs 8 is 10, with a thickness of 16 mm and a rectangular cross-section. The cross-section of the support and strengthening ribs 7 is trapezoidal, with a spacing of 250 mm.

[0028] Distribution optimization parameters can be carried out for the railway transportation fuel tank. In the static pressure stage, the deformation amount is constrained and tightened to ≤2.5 times the inner wall thickness as a constraint, and the number, thickness of the rib plates, and parameters of the buffer material are determined through finite element simulation; in the dynamic impact stage, with the goal that the plastic strain of the inner wall is ≤0.8 times the material limit value under the 80 MJ arc fault energy, the yield strength of the buffer material and the rib plate distribution are optimized. The buffer energy-absorbing material 4 is filled between the inner and outer tank walls, with a thickness of 150 mm, and the yield strength is increased to 20 MPa, and it is fixed by an adhesive bonding process. The rib plates 3 are evenly welded between the inner tank wall 1 and the outer tank wall 2, with a number of 12, a thickness of 12 mm, and a spacing of 500 mm, and are arranged in a denser pattern to enhance the local stiffness. Among them, the bolted overlap joints adopt a high-strength anti-loosening design, and the pre-tightening force and spacing are verified by finite element simulation to ensure the connection stability under vibration conditions; the installation of the outer tank wall can be carried out on-site to avoid the size constraints during railway transportation and adapt to the size limitations of railway transportation.

[0029] In summary, for the transformer tank wall provided in this embodiment, a composite tank wall is formed by arranging an outer tank wall outside the inner tank wall, and rib plates and buffer energy-absorbing materials are arranged between the two. Through the support and strengthening ribs arranged between the upper tank edge, the lower tank edge and the inner tank wall, a rigid-flexible composite support network is formed for the transformer tank wall, realizing an impact-resistant protection mechanism of "combining rigidity and flexibility", and further realizing the synergistic improvement of the static pressure strength and the dynamic impact resistance performance, and solving the problem that it is difficult to synergistically optimize the static pressure strength and the dynamic impact resistance performance of the existing tank wall.

[0030] It should be noted that in the description of the present invention, the terms indicating the direction or positional relationship such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0031] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A transformer oil tank wall, characterized in that: include: Inner box wall; An outer box wall is arranged outside the inner box wall along the length direction of the oil tank, and a buffer energy absorption cavity is formed between the outer box wall and the inner box wall. The buffer energy absorption cavity is filled with buffer energy absorption material, and a rib plate is also arranged in the buffer energy absorption cavity to provide local rigidity support; The upper box edge and the lower box edge are respectively arranged at the top and bottom ends of the inner box wall, and support reinforcement ribs are respectively provided between the upper box edge, the lower box edge and the top and bottom of the outer box wall, so that the support reinforcement ribs, the ribs and the outer box wall form a rigid support network to inhibit stress diffusion.

2. The transformer oil tank wall according to claim 1, characterized in that: Performing distributed optimization on the finite element model of the transformer tank wall to obtain optimized design parameters that meet constraint conditions; wherein the constraint conditions include: static pressure deformation constraint conditions and dynamic impact constraint conditions; the optimized design parameters include: the thickness of the buffer energy absorbing material, the yield strength of the buffer energy absorbing material, and the number of the ribs; The static pressure deformation constraint condition is that the transformer oil tank wall deformation under positive pressure of 120 kPa and negative pressure of 13 Pa is less than or equal to 3 times the thickness of the inner tank wall; The dynamic impact constraint condition is that when the inner box wall is subjected to an 80MJ arc fault energy impact, the ratio of its material dynamic limit strain to the plastic working strain should be greater than or equal to k; wherein, when the voltage level exceeds 800kV, k>1.4; when the voltage level exceeds 1000kV, k>1.

5.

3. The transformer oil tank wall according to claim 1 or 2, characterized in that: The outer box wall is a rectangular shell structure with one end open, and four side panels of the outer box wall are connected to the inner box wall.

4. The transformer oil tank wall according to claim 1 or 2, characterized in that: The buffering energy absorbing material is installed into the buffering energy absorbing cavity by an interference filling process, or the buffering energy absorbing material is connected to the inner wall of the buffering energy absorbing cavity by bonding.

5. The transformer oil tank wall according to claim 1 or 2, characterized in that: The inner box wall is made of Mn13 plastic steel, and its yield strength is ≥300MPa.

6. The transformer oil tank wall according to claim 1 or 2, characterized in that: The outer box wall is made of Q345B steel, and its yield strength is ≥400MPa.

7. The transformer oil tank wall according to claim 1 or 2, characterized in that: Outer wall reinforcement ribs are provided on the portion of the inner box wall exposed outside the buffer energy absorption cavity and on the outer wall of the outer box wall.

8. The transformer oil tank wall according to claim 1 or 2, characterized in that: The inner layer box wall is made by welding a plurality of modules together, and the welds of the inner layer box wall are arranged in a vertical direction, and each of the welds is located within the coverage of the buffer energy absorbing material.

9. The transformer oil tank wall according to claim 1 or 2, characterized in that: The cross section of the supporting reinforcement rib is trapezoidal or rectangular.

10. The transformer oil tank wall according to claim 1 or 2, characterized in that: The outer box wall and the inner box wall are connected by welding or by bolt jointing.

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