Liquid-immersed transformer

Abstract

The application relates to a liquid-immersed transformer which comprises a core column, a plurality of winding assemblies assembled on the core column and an iron yoke part, a high-voltage winding comprises at least one winding section; the iron yoke part comprises a first iron yoke and a second iron yoke; the winding section comprises a plurality of coil layers; according to a direction away from a low-voltage winding, a first end of each coil layer is gradually reduced in distance from the first iron yoke and then gradually increased in distance from the first iron yoke; a second end of each coil layer is gradually reduced in distance from the second iron yoke and then gradually increased in distance from the second iron yoke; the distance between the end of each coil layer of the high-voltage winding and the corresponding iron yoke is optimized, the traditional 66kV liquid-immersed transformer end portion corner ring insulation structure is abandoned, the winding end portion electric field is self-uniformized, the local field strength concentration is inhibited, the oil wedge defect generated by the traditional corner ring adhesion is completely eliminated, and the operation reliability of the insulation system is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of transformer technology, specifically, it relates to a liquid-immersed transformer. Background Technology

[0002] The area between the winding ends and the yoke of a liquid-immersed high-voltage transformer is a core weak point in the main insulation system. This area contains a large and uneven pure oil gap, resulting in severe electric field distortion and localized field strength concentration. This makes it highly susceptible to partial discharge, insulation aging, and even breakdown faults, directly determining the transformer's insulation reliability and service life.

[0003] To address the aforementioned issues, existing 66kV and other voltage-level liquid-immersed transformers generally employ the traditional insulation scheme of adding corner rings at the winding ends. By utilizing the barrier properties of the corner rings, the large single oil gap between the winding ends and the yoke is divided into multiple smaller oil gaps, effectively improving the overall electrical withstand strength of the oil gaps. At the same time, it reshapes the end electric field distribution and reduces the maximum local field strength, thus meeting the insulation safety requirements under high-voltage conditions.

[0004] However, in practical engineering applications, traditional corner ring insulation structures have many inherent defects, which restrict the development of lightweight, high-reliability, and low-cost transformers. First, the process is difficult to implement, requiring extremely high precision in corner ring molding and assembly fit, especially when adapting to cylindrical high-voltage winding structures, where the installation process is cumbersome, alignment accuracy is difficult to control, and production consistency is poor. Second, it is not economical, as the cost of specially molded corner ring materials is high, and the complex manual assembly process significantly increases production costs. Third, there are potential insulation risks, as the gaps between the corner ring and the coil and insulating paperboard can easily form irregular "oil wedge" structures, which can induce electric field distortion during long-term operation, thereby increasing the risk of partial discharge and reducing the stability and service life of the transformer insulation system. Summary of the Invention

[0005] The purpose of this invention is to provide a liquid-immersed transformer to solve the problems of complex assembly process, high cost, and potential insulation risks associated with the existing insulation scheme of adding corner rings to liquid-immersed transformers.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution: This invention proposes a liquid-immersed transformer, which includes: Iron core column; A plurality of winding assemblies are mounted on the iron core column; the winding assembly includes a low-voltage winding and a high-voltage winding, the high-voltage winding being located outside the low-voltage winding along the height direction of the iron core column, the high-voltage winding including at least one winding segment; The iron yoke section includes a first iron yoke and a second iron yoke, which are respectively connected to the two ends of the iron core column; The winding segment includes multiple coil layers; along the direction away from the low-voltage winding, the distance between the first end of each coil layer and the first yoke near the first yoke shows a trend of first gradually decreasing and then gradually increasing; the distance between the second end of each coil layer and the second yoke near the second yoke shows a trend of first gradually decreasing and then gradually increasing.

[0007] In some embodiments of this application, along the height direction of the core column, the high-voltage winding includes at least two winding segments; an insulating end ring is provided between adjacent winding segments, and the distance between the first or second end of each winding segment near the insulating end ring and the insulating end ring shows a trend of first gradually decreasing and then gradually increasing.

[0008] This solution sets the high-voltage winding as a multi-segment winding structure, and uses insulating end rings to isolate each winding segment. The end spacing of the winding segments connected to the insulating end rings is gradually optimized to avoid the problem of electric field distortion at the connection of segmented windings, completely eliminate the oil wedge discharge hazard caused by traditional corner rings, and ensure insulation stability.

[0009] In some embodiments of this application, the first end of each coil layer is provided with a first end insulation, and the second end of each coil layer is provided with a second end insulation; a first pressure plate is provided between the high-voltage winding and the first yoke, and a second pressure plate is provided between the high-voltage winding and the second yoke; the first assembly gap E1 formed between the first yoke and the upper end face of the high-voltage winding satisfies: 33mm≤E1≤36mm, and the second assembly gap E2 formed between the second yoke and the lower end face of the high-voltage winding satisfies: 28mm≤E2≤32mm.

[0010] The first and second pressure plates achieve insulation protection at the coil ends and axial clamping and fixing of the winding as a whole, effectively improving the stability of the winding structure and its resistance to short-circuit impacts. At the same time, the size range of the first assembly gap E1 and the second assembly gap E2 is precisely defined. Under the premise of completely eliminating the traditional corner ring insulation structure, a stable and complete corner ring-free end insulation system is constructed through standardized and controllable end gap matching end insulation and pressure plates.

[0011] In some embodiments of this application, the high-voltage winding includes an upper winding segment near the first yoke and a lower winding segment near the second yoke, with an insulating end ring provided between the upper winding segment and the lower winding segment, and the upper winding segment and the lower winding segment each including multiple coil layers.

[0012] In some embodiments of this application, the coil layer includes an innermost first-end wire layer, an outermost tap layer, and a plurality of intermediate wire layers located in the middle. The distance H1 between the first end of the first-end wire layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 98mm≤H1≤103mm; the distance H2 between the first end of the intermediate wire layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 68mm≤H2≤73mm; and the distance H3 between the first end of the tap layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 88mm≤H3≤92mm.

[0013] This solution defines differentiated spacing parameters for the first-end inlet layer, intermediate layer, and tap layer of the upper winding section, forming a gradient end profile structure without corner rings. By eliminating corner rings, it accurately balances the electric field intensity at the ends of different coil layers, completely solving the problems of oil wedge distortion and partial discharge caused by traditional corner rings, and significantly improving insulation reliability.

[0014] In some embodiments of this application, the distance h1 between the second end of the first end of the upper winding section's inlet layer, the first end of the lower winding section's inlet layer, and the corresponding insulating end ring all satisfy: 54mm≤h1≤58mm; The distance h2 between the second end of the middle wire layer of the upper winding segment, the first end of the middle wire layer of the lower winding and the corresponding insulating end ring both satisfy: 23mm≤h2≤27mm; The distance h3 between the second end of the tap layer of the upper winding segment, the first end of the tap layer of the lower winding, and the corresponding insulating end ring all satisfy: 40mm≤h3≤44mm.

[0015] In this embodiment, the spacing parameters of each coil layer at the insulated end rings of the upper and lower winding segments are defined to maintain the optimal gradient profile and uniform electric field distribution at the joint position of the winding segments. No corner rings are required for auxiliary insulation throughout the entire process, completely eliminating the potential hazards of the oil wedge structure in the joint area, stabilizing the end electric field, and significantly improving the reliability of the insulation system.

[0016] In some embodiments of this application, heat dissipation grooves are provided on both end faces of the insulating end ring, and the thickness t of the insulating end ring satisfies: 38mm≤t≤42mm.

[0017] In some embodiments of this application, the distance L1 between the second end of the first inlet layer of the lower winding segment and the lower end face of the high-voltage winding satisfies: 98mm≤L1≤103mm; the distance L2 between the second end of the middle inlet layer of the lower winding segment and the lower end face of the high-voltage winding satisfies: 68mm≤L2≤73mm; and the distance L3 between the second end of the tap layer of the lower winding segment and the lower end face of the high-voltage winding satisfies: 88mm≤L3≤92mm.

[0018] In some embodiments of this application, at least one intermediate winding segment is provided between the upper winding segment and the lower winding segment, and the distance h1 between the first end and the second end of the first end of the inlet layer of the intermediate winding segment and the adjacent insulating end ring all satisfy: 54mm≤h1≤58mm; The distance h2 between the first and second ends of the intermediate winding layer of the intermediate winding segment and the adjacent insulating end ring both satisfy: 23mm≤h2≤27mm; The distance h3 between the first and second ends of the tap layer of the intermediate winding section and the adjacent insulating end ring both satisfy: 40mm≤h3≤44mm.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are: The liquid-immersed transformer involved in this application optimizes the distance between the ends of each coil layer of the high-voltage winding and the corresponding iron yoke, abandoning the traditional corner ring insulation structure at the ends of the 66kV liquid-immersed transformer. Through precise electric field optimization design, the distance between the ends of each coil layer and the iron yokes at both ends is gradually distributed by first decreasing and then increasing. This can autonomously homogenize the electric field at the winding ends, suppress local field strength concentration, completely eliminate the oil wedge defects caused by traditional corner ring bonding, and significantly improve the operational reliability of the insulation system.

[0020] Meanwhile, the liquid-immersed transformer involved in this application eliminates the corner ring structure, saving the tedious processes of corner ring processing and alignment installation, greatly simplifying the overall assembly process of the transformer coil body, and effectively improving production assembly efficiency; it also eliminates the need for corner ring insulation consumables, directly reducing the amount of insulation material used and significantly lowering product manufacturing costs. This core structure is adaptable to various liquid-immersed high-voltage transformer winding structures, exhibiting strong versatility and a wide range of applications.

[0021] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a partial cross-sectional view of an embodiment of the liquid-immersed transformer proposed in this invention; Figure 2 This is a partial cross-sectional view of another embodiment of the liquid-immersed transformer proposed in this invention; Figure 3 This is a partial cross-sectional view of another embodiment of the liquid-immersed transformer proposed in this invention; In the picture, 100. Iron core column; 210. First yoke; 220. Second yoke; 301. Upper end face of high voltage winding; 302. Lower end face of high voltage winding; 310. Low-voltage winding; 320. High-voltage winding; 321. First-end inlet layer; 322. Intermediate layer; 323. Tap layer; 331. First-end insulation; 332. Second-end insulation; 333. Insulating end ring; 3201, Upper winding section; 3202, Lower winding section; 3203, Intermediate winding section; 401. First pressure plate component; 402. Second pressure plate component. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0030] Liquid-immersed transformers achieve voltage transformation and power transmission based on the principle of electromagnetic induction. During operation, the low-voltage winding 310 and the high-voltage winding 320 are magnetically coupled through a closed magnetic circuit formed by the core columns 100. When an AC voltage is applied to the low-voltage winding 310, the alternating current generates an alternating magnetic flux in the core. This alternating magnetic flux simultaneously penetrates the high-voltage winding 320. According to the law of electromagnetic induction, the high-voltage winding 320 induces a corresponding level of electromotive force, realizing the voltage conversion from low to high voltage and completing the power transmission and transformation functions.

[0031] The corner ring, as the core insulation barrier structure at the end, is conventionally installed in the large oil gap area between the end of the 320 high-voltage winding and the yoke. It is arranged around the circumference of the winding end and is located at the transition position between the winding end insulation and the yoke structure. It is used to cover the large open oil gap between the winding end and the yoke.

[0032] The installation of corner rings presents problems such as complex assembly processes, high costs, and potential insulation risks.

[0033] refer to Figure 1 To address the aforementioned problems, this invention proposes a liquid-immersed transformer, which includes a core column 100, a winding assembly mounted on the core column 100, and a yoke. The yoke includes a first yoke 210 and a second yoke 220 connected to both ends of the core column 100.

[0034] An assembly window is formed between the first yoke 210 and the second yoke 220, and the core post 100 and the winding assembly are located within the assembly window.

[0035] The winding assembly is arranged one-to-one on the outside of each iron core column 100. The winding assembly includes a low-voltage winding 310 and a high-voltage winding 320. The high-voltage winding 320 is located on the outside of the low-voltage winding 310. Along the height direction of the iron core column 100, the high-voltage winding 320 includes at least one winding segment.

[0036] The winding section includes multiple coil layers; the coil layers are wound sequentially from the inside to the outside of the low-voltage winding 310.

[0037] Along the direction away from the low-voltage winding 310, the distance between the first end of each coil layer and the first yoke 210 near the first yoke 210 shows a trend of first gradually decreasing and then gradually increasing; the distance between the second end of each coil layer and the second yoke 220 near the second yoke 220 shows a trend of first gradually decreasing and then gradually increasing.

[0038] In other words, along the direction from the inside out, the winding height of each coil layer on the iron core column 100 follows a trend of first increasing and then decreasing, so that the winding height of the inner coil layer and the outer coil layer is higher than that of the coil layer in the middle position.

[0039] The coil layer closest to the low-voltage winding 310 is the first-end inlet terminal. Since the voltage at the first-end inlet terminal is high, in order to reduce the field strength, it is designed to be further away from the coil end of the high-voltage winding 320 and the iron yoke. Similarly, the outermost coil layer is the tap layer 323, which is used to connect to the external wiring harness. Since the voltage is higher, it is also designed to be further away from the coil end of the high-voltage winding 320 and the iron yoke.

[0040] In order to ensure that the voltage of the coil layer in the middle position is relatively low, and therefore the electric field strength is small, the distance between it and the coil end of the high voltage winding 320 and the yoke is designed to be smaller.

[0041] This application optimizes the distance between the ends of each coil layer of the high-voltage winding 320 and the corresponding iron yoke, abandoning the traditional corner ring insulation structure at the ends of the 66kV liquid-immersed transformer. Through precise electric field optimization design, the distance between the ends of each coil layer and the iron yokes at both ends is gradually distributed by first decreasing and then increasing. This can autonomously homogenize the electric field at the winding ends, suppress local field strength concentration, completely eliminate the oil wedge defects caused by traditional corner ring bonding, and significantly improve the operational reliability of the insulation system.

[0042] Meanwhile, the liquid-immersed transformer involved in this application eliminates the corner ring structure, saving the tedious processes of corner ring processing and alignment installation, greatly simplifying the overall assembly process of the transformer coil body, and effectively improving production assembly efficiency; it also eliminates the need for corner ring insulation consumables, directly reducing the amount of insulation material used and significantly lowering product manufacturing costs. This core structure is adaptable to various liquid-immersed high-voltage transformer winding structures, exhibiting strong versatility and a wide range of applications.

[0043] In some embodiments of this application, a first end insulation 331 is provided at the first end of each coil layer, and a second end insulation 332 is provided at the second end of each coil layer; the end insulation is provided close to the end face of the coil layer, which can completely cover and protect the cut edges of the coil end wire and the insulating paper, make up for the weak insulation defects at the coil end, and avoid the phenomenon of sharp electric field concentration at the edge of the bare wire and the insulation cut.

[0044] In some embodiments of this application, the high-voltage winding 320 includes at least two winding segments along the height direction of the core column 100.

[0045] Combination Figure 2 In one specific embodiment, the winding assembly is a dual-winding structure, with two winding segments arranged along the height direction of the iron core column 100. An insulating end ring 333 is provided between adjacent winding segments. The distance between the first or second end of each winding segment and the insulating end ring 333 shows a trend of first gradually decreasing and then gradually increasing.

[0046] This solution sets the high-voltage winding 320 as a multi-segment winding structure, and uses the insulating end ring 333 to isolate each winding segment. The end spacing of the winding segment connecting to the insulating end ring 333 is gradually optimized to avoid the electric field distortion problem at the connection of the segmented windings, completely eliminate the oil wedge discharge hazard caused by the traditional corner ring, and ensure insulation stability.

[0047] A first pressure plate 401 is disposed between the high-voltage winding 320 and the first yoke 210, and a second pressure plate 402 is disposed between the high-voltage winding 320 and the second yoke 220, respectively arranged at the two axial ends of the high-voltage winding 320. In the defined operating state, the first yoke 210 is located above the winding assembly, and the second yoke 220 is located below the winding assembly. The first pressure plate 401 is sandwiched between the first yoke 210 and the high-voltage winding 320, and the second pressure plate 402 is sandwiched between the second yoke 220 and the high-voltage winding 320. The pressure plates are arranged to fit snugly against the outer side of the winding end insulation, positioned in the gap between the yoke structure and the winding end, without occupying the effective insulation area of ​​the winding. The pressure plates are made entirely of high-strength insulating material, possessing excellent insulation and mechanical compressive strength.

[0048] The pressure plate component includes an axial clamping and positioning function. By applying uniform axial pressure to the high-voltage winding 320 as a whole through the upper and lower sets of pressure plates, the segmented winding sections, insulating end rings 333, and end insulation are clamped and fixed, effectively limiting the axial movement and deformation of the winding under long-term operation and short-circuit impact conditions, significantly improving the overall structural rigidity and short-circuit impact resistance of the winding, and ensuring the stability of the transformer body structure.

[0049] refer to Figure 2The first assembly gap E1 formed between the first yoke 210 and the upper end face 301 of the high voltage winding satisfies: 33mm≤E1≤36mm, and the second assembly gap E2 formed between the second yoke 220 and the lower end face 302 of the high voltage winding satisfies: 28mm≤E2≤32mm.

[0050] The first pressure plate 401 and the second pressure plate 402 achieve insulation protection at the coil ends and axial clamping and fixing of the winding as a whole, effectively improving the stability of the winding structure and its resistance to short-circuit impacts. At the same time, the size range of the first assembly gap E1 and the second assembly gap E2 is precisely defined. Under the premise of completely eliminating the traditional corner ring insulation structure, a stable and complete corner ring-free end insulation system is constructed through standardized and controllable end gap matching end insulation and pressure plate components.

[0051] The height of the first pressure plate 401 and the second pressure plate 402 is 70mm. The first pressure plate 401 and the second pressure plate 402 extend into the assembly window by 25mm. A 10mm press-fit gap is formed between the first pressure plate 401 and the second pressure plate 402 and the winding assembly.

[0052] In some embodiments of this application, the high-voltage winding 320 includes an upper winding section 3201 near the first yoke 210 and a lower winding section 3202 near the second yoke 220. An insulating end ring 333 is provided between the upper winding section 3201 and the lower winding section 3202. The upper winding section 3201 and the lower winding section 3202 each include multiple coil layers.

[0053] In some embodiments of this application, along the radial direction of the high-voltage winding 320, the multi-layer coil of the winding segment can be divided into three structural levels: the innermost first-end entry layer 321, the outermost tap layer 323, and the multi-layer intermediate layer 322 between the first-end entry layer 321 and the tap layer 323. The number of intermediate layers 322 is not limited to a single-layer structure; two or more layers can be set according to voltage insulation margin and electric field optimization requirements to adapt to the insulation and heat dissipation requirements of different operating conditions.

[0054] The two end faces of the high-voltage winding 320 are the upper end face 301 and the lower end face 302. The upper end face 301 is located at the end closer to the first yoke 410, and the lower end face 302 is located at the end closer to the second yoke 420.

[0055] The distance H1 between the first end of the first end of the inlet layer 321 of the upper winding section 3201 and the upper end face 301 of the high voltage winding satisfies: 98mm≤H1≤103mm; the distance H2 between the first end of the intermediate wire layer 322 of the upper winding section 3201 and the upper end face 301 of the high voltage winding satisfies: 68mm≤H2≤73mm; the distance H3 between the first end of the tap layer 323 of the upper winding section 3201 and the upper end face 301 of the high voltage winding satisfies: 88mm≤H3≤92mm.

[0056] The coil layer between the first-end incoming layer 321 and the intermediate layer 322 has a stepped transition.

[0057] Similarly, the coil layers between the intermediate line layer 322 and the tap line layer 323 also have a stepped transition.

[0058] This solution defines differentiated spacing parameters for the first-end inlet layer 321, the middle layer 322, and the tap layer 323 of the upper winding section 3201, forming a gradient end profile structure without corner rings. By eliminating corner rings, the electric field intensity at the ends of different coil layers is precisely balanced, completely solving the problems of oil wedge distortion and partial discharge caused by traditional corner rings, and significantly improving insulation reliability.

[0059] In some embodiments of this application, the distance h1 between the second end of the first end of the upper winding section 3201 and the first end of the lower winding section 321 and the corresponding insulating end ring 333 both satisfy: 54mm≤h1≤58mm; The distance h2 between the second end of the intermediate wire layer 322 of the upper winding section 3201 and the first end of the intermediate wire layer 322 of the lower winding and the corresponding insulating end ring 333 both satisfy: 23mm≤h2≤27mm; The distance h3 between the second end of the tap layer 323 of the upper winding section 3201 and the first end of the tap layer 323 of the lower winding and the corresponding insulating end ring 333 both satisfy: 40mm≤h3≤44mm.

[0060] In this embodiment, the spacing parameters of each coil layer at the mating insulation end ring 333 of the upper and lower winding segments 3202 are limited, so that the winding segment mating position maintains the optimal gradient profile and uniform electric field distribution. No corner ring auxiliary insulation is required throughout the entire process, completely eliminating the potential hazards of the oil wedge structure in the mating area, stabilizing the end electric field, and significantly improving the reliability of the insulation system.

[0061] In some embodiments of this application, the distance L1 between the second end of the first end of the inlet layer 321 of the lower winding segment 3202 and the lower end face 302 of the high voltage winding satisfies: 98mm≤L1≤103mm; the distance L2 between the second end of the intermediate wire layer 322 of the lower winding segment 3202 and the lower end face 302 of the high voltage winding satisfies: 68mm≤L2≤73mm; and the distance L3 between the second end of the tap layer 323 of the lower winding segment 3202 and the lower end face 302 of the high voltage winding satisfies: 88mm≤L3-E2≤92mm.

[0062] The end of the high-voltage winding 320 is the lower end face 302 of the high-voltage winding, which corresponds to the second end of the lower winding segment 3202.

[0063] The gap design between the upper winding section 3201 and the first yoke 210 forms a basically symmetrical structure, eliminating the need for corner ring auxiliary field insulation, thus eliminating oil wedge defects at the source and improving the overall insulation reliability of the transformer.

[0064] Combination Figure 3 In some embodiments of this application, at least one intermediate winding segment 3203 is provided between the upper winding segment 3201 and the lower winding segment 3202. That is, along the iron core column 100, each winding assembly includes at least three winding segments, and an insulating end ring 333 is provided between adjacent winding assemblies.

[0065] Except for the upper winding section 3201 and the lower winding section 3202, the intermediate winding section 3203 located between the insulating end rings 333 satisfies: The distance h1 between the first end and the second end of the first end of the inlet layer 321 of the intermediate winding section 3203 and the adjacent insulating end ring 333 all satisfy: 54mm≤h1≤58mm; The distance h2 between the first and second ends of the intermediate wire layer 322 of the intermediate winding section 3203 and the adjacent insulating end ring 333 both satisfy: 23mm≤h2≤27mm; The distance h3 between the first and second ends of the tap layer 323 of the intermediate winding section 3203 and the adjacent insulating end ring 333 both satisfy: 40mm≤h3≤44mm.

[0066] In some embodiments of this application, heat dissipation grooves are provided on both end faces of the insulating end ring 333, and the thickness t of the insulating end ring 333 satisfies: 38mm≤t≤42mm.

[0067] Below, taking a 66kV liquid-immersed transformer as an example, a specific size selection method is proposed: The winding assembly includes two winding segments: from top to bottom, the upper winding segment 3201 and the lower winding segment 3202, with an insulating end ring 333 provided between the upper winding segment 3201 and the lower winding segment 3202.

[0068] The first assembly gap E1 formed between the first yoke 210 and the end of the corresponding high-voltage winding 320 is 35mm, and the second assembly gap E2 formed between the second yoke 220 and the end of the corresponding high-voltage winding 320 is 30mm.

[0069] The distance H1 between the first end of the first end of the first end of the first end of the incoming layer 321 of the upper winding section 3201 and the first yoke 210 satisfies: H1-E1=100mm, that is, the size of the first end insulation 331 corresponding to the first end of the incoming layer 321 is 100mm; the distance H2 between the first end of the first end of the intermediate layer 322 of the upper winding section 3201 and the first yoke 210 satisfies: H2-E1=70mm, that is, the size of the first end insulation 331 corresponding to the intermediate layer 322 is 70mm; the distance H3 between the first end of the tap layer 323 of the upper winding section 3201 and the first yoke 210 satisfies: H3-E1=90mm, that is, the size of the first end insulation 331 corresponding to the first end of the tap layer 323 is 90mm. The size of the first end insulation 331 has a trend of decreasing first and then increasing along the inner layer to the outer layer.

[0070] The distance h1 between the second end of the first end of the inlet layer 321 of the upper winding section 3201 and the first end of the first end of the inlet layer 321 of the lower winding and the corresponding insulating end ring 333 both satisfy: h1=55mm; that is, the end insulation dimension between the first end of the inlet layer 321 of the upper winding section 3201 and the first end of the inlet layer 321 of the lower winding section 3202 and the insulating end ring 333 is 55mm.

[0071] The distance h2 between the second end of the intermediate wire layer 322 of the upper winding segment 3201 and the first end of the intermediate wire layer 322 of the lower winding and the corresponding insulating end ring 333 both satisfy: h2=25mm; that is, the end insulation dimension between the intermediate wire layer 322 of the upper winding segment 3201 and the insulating end ring 333 of the lower winding segment 3202 is 25mm.

[0072] The distance h3 between the second end of the tap layer 323 of the upper winding section 3201 and the first end of the tap layer 323 of the lower winding and the corresponding insulating end ring 333 both satisfy: h3=42mm, that is, the end insulation dimension between the tap layer 323 of the upper winding section 3201 and the insulating end ring 333 of the lower winding section 3202 is 42mm.

[0073] The distance L1 between the second end of the first end of the inlet layer 321 of the lower winding section 3202 and the second yoke 220 satisfies: L1-E2=100mm; that is, the size of the second end insulation 332 corresponding to the second end of the first end inlet layer 321 is 100mm.

[0074] The distance L2 between the second end of the intermediate wire layer 322 of the lower winding segment 3202 and the second yoke 220 satisfies: L2-E2=70mm; that is, the size of the second end insulation 332 corresponding to the second end of the intermediate wire layer 322 is 70mm.

[0075] The distance L3 between the second end of the tap layer 323 of the lower winding section 3202 and the second yoke 220 satisfies: L3-E2=90mm, that is, the size of the second end insulation 332 corresponding to the second end of the tap layer 323 is 70mm.

[0076] The thickness of the insulating end ring 333 is sufficient to ensure that there is enough insulation distance between the winding segments to meet the electrical insulation margin requirements and prevent discharge breakdown between the winding segments. At the same time, the thickness is not too large to avoid occupying too much axial space of the winding, which would increase the overall height of the transformer and increase material consumption. The thickness is also not too small to ensure that the insulating end ring 333 has sufficient mechanical strength to withstand the axial pressure brought by the winding compression, prevent deformation and cracking under pressure, and ensure the overall structural stability of the segmented winding.

[0077] The insulating end ring 333 has heat dissipation grooves on both end faces of the winding sections. These grooves can be recessed structures formed on the end faces of the end ring, extending circumferentially along the insulating end ring 333. When the transformer is immersed in insulating oil, the heat dissipation grooves form oil channels for the insulating oil to flow through. The insulating oil can reach the contact points between the winding sections and the insulating end ring 333 via the heat dissipation grooves, improving the oil circulation at the winding section connection point, promptly removing heat generated during winding operation, reducing local temperature rise in the winding connection area, and preventing localized overheating that accelerates insulation aging.

[0078] In this invention, all the defined structural dimensional parameters, such as the end assembly gap, the distance between the coil layer and the yoke, the distance between the coil layer and the insulating end ring 333, and the thickness of the insulating end ring 333, are obtained through simulation calculation and iterative optimization using a three-dimensional electric field finite element simulation model. This allows for precise adaptation to the electric field distribution characteristics and insulation tolerance requirements of the 66kV liquid-immersed transformer without corner ring insulation structure.

[0079] Specifically, the three-dimensional electric field finite element simulation model built in this application completely reproduces all the key structures of the transformer body. The modeling objects include core pillars 100, upper and lower yokes, multi-layer high-voltage coil layers, low-voltage windings 310, insulating paperboard, winding support bars, upper and lower end insulation, middle insulating end rings 333, and upper and lower pressure plates, etc., avoiding distortion of electric field calculation due to structural simplification.

[0080] During the simulation modeling process, each structural component in the model is assigned material and electrical parameters under actual operating conditions. The dielectric constant and electrical breakdown strength parameters of various conductor materials and insulating materials are precisely configured to realistically restore the multi-dielectric composite electric field environment inside the transformer, ensuring that the simulation calculation results are highly consistent with the actual operating conditions.

[0081] By performing fine meshing on areas with concentrated electric field distortion, such as the winding ends, winding segment docking positions, and the periphery of the insulating end ring 333, the local electric field distribution, the location of the maximum electric field, and the insulation margin of each key area under the corner ring-less structure are accurately solved. Through multiple rounds of iterative simulation and comparative optimization of structural dimensions, under the constraints of overall electrical insulation strength, no partial discharge, and sufficient insulation margin, the optimal numerical ranges of each assembly gap, coil end spacing, and insulation end ring 333 thickness are optimized, and finally all structural limiting parameters of the present invention are determined.

[0082] Whenever possible, the various aspects and features described and shown in the specification can be applied individually, and these individual aspects can serve as the subject of a divisional application.

[0083] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0084] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A liquid-immersed transformer, characterized in that, include: Iron core column; A plurality of winding assemblies are mounted on the iron core column; the winding assembly includes a low-voltage winding and a high-voltage winding, the high-voltage winding being located outside the low-voltage winding along the height direction of the iron core column, the high-voltage winding including at least one winding segment; The iron yoke section includes a first iron yoke and a second iron yoke, which are respectively connected to the two ends of the iron core column; The winding segment includes multiple coil layers; the distance from the first end of each coil layer to the first yoke gradually decreases and then gradually increases along the direction away from the low-voltage winding; the distance from the second end of each coil layer to the second yoke gradually decreases and then gradually increases.

2. The liquid-immersed transformer according to claim 1, characterized in that, Along the height direction of the core column, the high-voltage winding includes at least two winding segments; an insulating end ring is provided between adjacent winding segments, and the distance between the first or second end of each winding segment near the insulating end ring and the insulating end ring shows a trend of first gradually decreasing and then gradually increasing.

3. The liquid-immersed transformer according to claim 2, characterized in that, Each coil layer has a first end insulated and a second end insulated. A first pressure plate is provided between the high-voltage winding and the first yoke, and a second pressure plate is provided between the high-voltage winding and the second yoke. The first assembly gap E1 formed between the first yoke and the upper end face of the high-voltage winding satisfies: 33mm≤E1≤36mm. The second assembly gap E2 formed between the second yoke and the lower end face of the high-voltage winding satisfies: 28mm≤E2≤32mm.

4. The liquid-immersed transformer according to claim 3, characterized in that, The high-voltage winding includes an upper winding section near the first yoke and a lower winding section near the second yoke. An insulating end ring is provided between the upper winding section and the lower winding section. The upper winding section and the lower winding section each include multiple coil layers.

5. The liquid-immersed transformer according to claim 4, characterized in that, The coil layer includes an innermost first-end wire layer, an outermost tap layer, and multiple intermediate wire layers located in the middle. The distance H1 between the first end of the first-end wire layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 98mm≤H1≤103mm; the distance H2 between the first end of the intermediate wire layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 68mm≤H2≤73mm; and the distance H3 between the first end of the tap layer of the upper winding segment and the upper end face of the high-voltage winding satisfies: 88mm≤H3≤92mm.

6. The liquid-immersed transformer according to claim 4, characterized in that, The distance h1 between the second end of the first end of the upper winding section, the first end of the first end of the lower winding section, and the corresponding insulating end ring all satisfy: 54mm≤h1≤58mm; The distance h2 between the second end of the middle wire layer of the upper winding segment, the first end of the middle wire layer of the lower winding and the corresponding insulating end ring both satisfy: 23mm≤h2≤27mm; The distance h3 between the second end of the tap layer of the upper winding segment, the first end of the tap layer of the lower winding, and the corresponding insulating end ring all satisfy: 40mm≤h3≤44mm.

7. The liquid-immersed transformer according to claim 4, characterized in that, The insulating end ring has heat dissipation grooves on both end faces, and the thickness t of the insulating end ring satisfies: 38mm≤t≤42mm.

8. The liquid-immersed transformer according to claim 4, characterized in that, The distance L1 between the second end of the first inlet layer of the lower winding section and the lower end face of the high-voltage winding satisfies: 98mm≤L1≤103mm; the distance L2 between the second end of the middle inlet layer of the lower winding section and the lower end face of the high-voltage winding satisfies: 68mm≤L2≤73mm; the distance L3 between the second end of the tap layer of the lower winding section and the lower end face of the high-voltage winding satisfies: 88mm≤L3≤92mm.

9. The liquid-immersed transformer according to claim 4, characterized in that, At least one intermediate winding segment is provided between the upper winding segment and the lower winding segment. The distance h1 between the first end and the second end of the first end of the inlet layer of the intermediate winding segment and the adjacent insulating end ring all satisfy: 54mm≤h1≤58mm. The distance h2 between the first and second ends of the intermediate winding layer of the intermediate winding segment and the adjacent insulating end ring both satisfy: 23mm≤h2≤27mm; The distance h3 between the first and second ends of the tap layer of the intermediate winding section and the adjacent insulating end ring both satisfy: 40mm≤h3≤44mm.

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