Transformer and low-voltage winding thereof

Abstract

The invention discloses a transformer and a low-voltage winding thereof, and solves the problems of limited foil specification type selection of a foil coil under the condition of large current, overlarge current density of the end part of the foil coil, and related structure layout difficulty caused by the increase of the specification of a conducting bar. The low-voltage winding comprises a first foil winding coil 1, a second foil winding coil 2 and a conducting bar lead 4, the first foil winding coil 1 and the second foil winding coil 2 are respectively sleeved on the upper part and the lower part of an iron core column 3 of the transformer; the first foil winding coil 1 and the second foil winding coil 2 are provided with incoming and outgoing lines; an inlet wire of the first foil winding coil 1 is communicated with an inlet wire of the second foil winding coil 2 through the conducting bar lead 4, and an outlet wire of the first foil winding coil 1 is communicated with an outlet wire of the second foil winding coil 2 through the conducting bar lead 4. The first foil winding coil 1 and the second foil winding coil 2 are the same in specification and winding direction.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to a transformer and a low-voltage winding thereof. Background Art

[0002] As the capacity of the transformer increases, in order to meet the higher power transmission requirements, the current of its low-voltage winding also increases. However, when the low-voltage winding adopts foil-wound coils, the increase of low-voltage winding current will cause a series of problems:

[0003] 1) As the current of low-voltage windings increases, the foil specifications used in foil-wound coils also need to be increased and adjusted; however, due to the limitations of foil specifications and the processing capacity of foil winding machines, conventional foil widths may not meet the requirements of transformer design;

[0004] 2) When the foil width is large, under the influence of the leakage magnetic field, the "squeeze flow" phenomenon will occur in the foil coil, that is, the current density at both ends of the foil is significantly larger than that in the middle. This phenomenon will cause local overheating at both ends of the foil, and as the foil width increases, the "squeeze flow" phenomenon will become more obvious;

[0005] 3) As the current of the low-voltage winding increases, the specifications of the conductive bar used to conduct the current generated by the foil-wound coil to the external circuit also need to be increased and adjusted. Then, after the conductive bar is buried (i.e., the conductive bar is embedded and fixed in the structure of the foil-wound coil), the radial size of the foil-wound coil will be increased due to the larger specifications of the conductive bar. This will not only occupy the thickness of the iron core sheet, but also cause the foil-wound coil to deviate from the circular shape, thereby reducing the short-circuit resistance of the foil-wound coil. Summary of the invention

[0006] In view of the above problems, the present application provides a transformer and a low-voltage winding thereof to solve the problem of limited foil specification selection faced by foil-wound coils under high current conditions, the problem of excessive current density at the ends of foil-wound coils, and the related structural layout difficulties caused by the increase in the specifications of the conductive bar. The specific solution is as follows:

[0007] A first aspect of the present application provides a low-voltage winding of a transformer, comprising:

[0008] A first foil-wound coil 1, a second foil-wound coil 2 and a conductive row lead 4;

[0009] The first foil-wound coil 1 and the second foil-wound coil 2 are respectively used to be mounted on the upper part and the lower part of the iron core column 3 of the transformer;

[0010] The first foil-wound coil 1 and the second foil-wound coil 2 are both provided with input and output wires; the input wire of the first foil-wound coil 1 is connected with the input wire of the second foil-wound coil 2 through the conductive row lead wire 4, and the output wire of the first foil-wound coil 1 is also connected with the output wire of the second foil-wound coil 2 through the conductive row lead wire 4;

[0011] The first foil-wound coil 1 and the second foil-wound coil 2 have the same specifications and the same winding direction.

[0012] In one possible implementation, the wire inlet of the conductive row of the first foil-wound coil 1 and the wire outlet of the conductive row of the second foil-wound coil 2 are in opposite directions, one facing upward and the other facing downward; the wire outlet of the conductive row of the first foil-wound coil 1 and the wire inlet of the conductive row of the second foil-wound coil 2 are in opposite directions, one facing upward and the other facing downward.

[0013] In a possible implementation, the conductive row leads 4 are connected to form several frame structures, which play the role of current convergence; the low-voltage lead wires of the first foil-wound coil 1 and the second foil-wound coil 2 of each phase are firstly converged through the conductive row leads 4 and then divided into two paths, and finally led out from the transformer through the bushing lead wires 5.

[0014] A second aspect of the present application provides a transformer, comprising: a low-voltage winding of the transformer according to the above-mentioned first aspect or any implementation of the first aspect.

[0015] In a possible implementation, the magnetic core of the transformer includes a middle iron yoke insulation; the middle iron yoke insulation is placed in the middle iron yoke part of the transformer core and is located between the first foil-wound coil 1 and the second foil-wound coil 2 .

[0016] In a possible implementation, at least one opening is provided on the middle iron yoke insulation, and the opening is used to ensure smooth flow of upper and lower oil passages of the foil-wound coil.

[0017] In a possible implementation, the transformer is an offshore wind power transformer.

[0018] By means of the above technical scheme, the low-voltage winding of the transformer provided in the present application divides the original foil-wound coil into two independent upper and lower foil-wound coils, and operates the two foil-wound coils in parallel so that half of the current of the original foil-wound coil flows through each foil-wound coil. This effectively solves the problems of limited selection of foil specifications of the foil-wound coil under high current conditions, excessive current density at the ends of the foil-wound coil, and related structural layout difficulties caused by increased specifications of the conductive bar, thereby improving the operating efficiency and reliability of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0020] Figure 1 A schematic diagram of the structure of a low-voltage winding of a transformer provided in this application;

[0021] Figure 2 A lead connection diagram of a low-voltage winding of a transformer provided in this application.

[0022] Reference numerals:

[0023] 1-first foil-wound coil; 2-second foil-wound coil; 3-core column; 4-conductive row lead wire; 5-casing lead wire. DETAILED DESCRIPTION

[0024] As the capacity of transformers (such as offshore wind power transformers) increases, in order to meet higher power transmission requirements, the current of their low-voltage windings also increases. The low-voltage windings of transformers can be composed of foil-wound coils. Foil-wound coils, also known as foil coils, are inductors made of copper foil or aluminum foil and other high-conductivity foils as conductor materials, wound by foil winding machines. They have many advantages, such as high mechanical strength, good electrical performance, easy winding processing, high production efficiency, compact and stable structure, high thermal conductivity, strong corrosion resistance, and effective resistance to electromagnetic interference and vibration.

[0025] However, when the low voltage winding adopts foil wound coil, the increase of low voltage winding current will cause a series of problems, the parameters are as follows 1)~3):

[0026] 1) As the current of low-voltage windings increases, the foil specifications (including the width and thickness of the foil) used in foil-wound coils also need to be increased and adjusted to carry higher currents. However, in the actual design and manufacturing process, due to the limitations of foil specifications and the processing capabilities of foil winding machines, conventional foil widths may not meet the requirements of transformer design.

[0027] 2) When the transformer is working, a leakage magnetic field is generated, which is generated when the current flows in the winding. The foil width of a conventional foil-wound coil is close to the transformer window height. Due to the large width of the foil, the magnetic field environment at both ends is different from that in the middle. Under the influence of the leakage magnetic field, a "squeeze flow" phenomenon will occur in the foil coil, that is, the current density at both ends of the foil is significantly greater than that in the middle. As the width of the foil increases, the "squeeze flow" phenomenon will become more and more obvious, causing local overheating at both ends of the foil, thereby accelerating the aging process of the low-voltage winding insulation (the insulating material or insulating structure used to isolate the low-voltage winding from other components, such as the iron core, high-voltage winding, transformer casing, etc.), shortening the overall service life of the transformer.

[0028] 3) The conductive bus is used to conduct current from the foil-wound coil and connect it to the external circuit. As the current of the low-voltage winding increases, a larger conductive bus is needed to carry the current. Then, after the conductive bus is buried (burying the conductive bus means embedding and fixing the conductive bus in the structure of the foil-wound coil through a specific process and method), the radial size of the foil-wound coil will be significantly increased due to the larger size of the conductive bus. This will not only occupy more of the thickness of the iron core sheet, resulting in an increase in the overall size of the transformer, but also cause the shape of the foil-wound coil to deviate from a circle, resulting in a decrease in the short-circuit resistance of the foil-wound coil (non-circular coils are more likely to deform when subjected to short-circuit current impact due to their structural instability, so non-circular coils have lower short-circuit resistance than circular coils).

[0029] In the case where the low-voltage winding adopts a foil-wound coil, in order to reduce the negative impact caused by the excessive current of the low-voltage winding, an embodiment of the present application provides a low-voltage winding of a transformer. The low-voltage winding divides the original foil-wound coil into two upper and lower independent foil-wound coils, and runs the two foil-wound coils in parallel so that each foil-wound coil flows half of the original foil-wound coil current, effectively solving the problems of limited foil sheet specification selection of foil-wound coils, excessive current density at the ends of foil-wound coils, and related structural layout difficulties caused by increased conductive bar specifications under high current conditions, thereby improving the operating efficiency and reliability of the transformer.

[0030] The following is a clear and complete description of a low-voltage winding of a transformer provided by an embodiment of the present application in conjunction with the accompanying drawings. Obviously, the described embodiment is only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0031] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances. This is just a way of distinguishing objects with the same attributes when describing the embodiments of this application.

[0032] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear at different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0033] See also Figure 1 The low voltage winding structure shown and Figure 2 The low-voltage winding lead connection diagram shown in the embodiment of the present application provides a low-voltage winding of a transformer, comprising: a first foil-wound coil 1, a second foil-wound coil 2 and a conductive row lead 4;

[0034] The first foil-wound coil 1 and the second foil-wound coil 2 are respectively used to be mounted on the upper part and the lower part of the iron core column 3 of the transformer;

[0035] The first foil-wound coil 1 and the second foil-wound coil 2 are each provided with a group of lead wires; this group of lead wires (also called input and output wires) includes a lead wire for receiving current (also called input wire) and a lead wire for outputting current (also called output wire); the input wire of the first foil-wound coil 1 is connected with the input wire of the second foil-wound coil 2 through the conductive row lead wire 4, and the output wire of the first foil-wound coil 1 is also connected with the output wire of the second foil-wound coil 2 through the conductive row lead wire 4, so that the first foil-wound coil 1 and the second foil-wound coil 2 are connected in parallel;

[0036] The first foil-wound coil 1 and the second foil-wound coil 2 have the same specifications and the same winding direction.

[0037] The working principle of the embodiment of the present application is described in detail below:

[0038] The transformer is mainly composed of core components such as the iron core (also called the magnetic core) and windings. The iron core is the main magnetic circuit part of the transformer, consisting of an iron core column and an iron yoke. The iron core column is covered with windings and is a key component of the transformer for electromagnetic induction and energy conversion. The iron yoke is used to connect the iron core columns to form a closed magnetic circuit to ensure the smooth flow of magnetic flux. In order to reduce eddy current loss and hysteresis loss, the iron core column is usually made of stacked thin silicon steel sheets, and the iron yoke is also mainly made of thin silicon steel sheets.

[0039] The windings mounted on the core column 3 include a low-voltage winding and a high-voltage winding. Specifically, when AC current is passed through the high-voltage winding, it will generate a magnetic flux in the core column 3, and this magnetic flux will pass through the low-voltage winding, thereby inducing an electromotive force in the low-voltage winding, and realizing the conversion of high-voltage electricity to low-voltage electricity (the transformer at this time is a step-down transformer); conversely, when AC current is passed through the low-voltage winding, it will also generate a magnetic flux in the core column 3, and this magnetic flux will pass through the high-voltage winding, thereby inducing an electromotive force in the high-voltage winding, and realizing the conversion of low-voltage electricity to high-voltage electricity (the transformer at this time is a step-up transformer).

[0040] In the case where a foil-wound coil is used for the low-voltage winding, in order to solve the many problems that exist when the current of the low-voltage winding is too large, the embodiment of the present application divides the single foil-wound coil used by the low-voltage winding into two upper and lower independent foil-wound coils, namely a first foil-wound coil 1 and a second foil-wound coil 2; the two foil-wound coils are operated in parallel to share the current, and each foil-wound coil passes half of the current of the original foil-wound coil. In this way, the current can be effectively dispersed while the total current-carrying capacity remains unchanged, thereby solving the problems of limited selection of foil specifications of the foil-wound coil, excessive current density at the ends of the foil-wound coil, and related structural layout difficulties caused by increased specifications of the conductive bar when the current flowing through a single foil-wound coil is too large.

[0041] Among them, the single foil-wound coil used in the low-voltage winding is divided into two upper and lower independent foil-wound coils, specifically: the first foil-wound coil 1 and the second foil-wound coil 2 are respectively mounted on the upper and lower parts of the transformer core column 3; and the first foil-wound coil 1 and the second foil-wound coil 2 have the same specifications and the same winding direction.

[0042] Specifically, the first foil-wound coil 1 and the second foil-wound coil 2 have the same winding direction, which ensures that the magnetic fields generated by the two foil-wound coils are in the same direction when working. The advantages thereof are shown in 1) to 2 below):

[0043] 1) Ensure the magnetic field superposition effect:

[0044] The same winding direction ensures that the magnetic fields generated by the two foil coils are in the same direction when power is applied.

[0045] When two or more magnetic fields exist at a certain point in space at the same time, the magnetic induction intensity generated by these magnetic fields at that point is the vector sum of the magnetic induction intensity generated by each magnetic field at that point. This is the magnetic field superposition effect. Therefore, when the magnetic fields generated by the two foil coils have the same direction, the magnetic induction intensity they generate at that point will be added together, so that the total magnetic induction intensity is enhanced. This enhancement effect helps to improve the electrical performance of the transformer, such as increasing the current carrying capacity and reducing energy consumption.

[0046] 2) Maintaining electromagnetic balance:

[0047] The same winding direction helps to maintain the stability of the electromagnetic relationship within the entire transformer. If the winding directions are different, the magnetic fields generated by the two foil coils will interfere with each other, destroying the electromagnetic balance and causing the transformer to perform poorly, such as voltage fluctuations and increased losses.

[0048] In addition, the specifications of the first foil-wound coil 1 and the second foil-wound coil 2 are the same, which means that the width, thickness, number of turns, etc. of the first foil-wound coil 1 and the second foil-wound coil 2 are all consistent, which ensures that when the two foil-wound coils are operated in parallel, the total current can be evenly distributed to the two foil-wound coils, and each foil-wound coil flows through half of the current of the original foil-wound coil.

[0049] In addition, since the current flowing through the two foil-wound coils is significantly reduced compared to the original foil-wound coil, the problems of limited foil specification selection, excessive current density at the ends of the foil-wound coil, and related structural layout difficulties caused by increased specifications of the conductive bar when the current flowing through a single foil-wound coil is too large are effectively solved. For specific analysis, see 1) to 3 below):

[0050] 1) Solve the problem of limited foil specifications for foil wound coils:

[0051] Since the current carried by each foil coil is only half of that of the original foil coil, each foil coil can use a smaller foil, thereby bypassing the restrictions on the foil specifications and the processing capacity of the foil winding machine when the current of the original foil coil is large (mainly getting rid of the restrictions on the height of the foil coil due to the foil specifications). In this way, the foil width and thickness of each foil coil can be within the specifications of existing equipment and materials, which not only meets the current carrying requirements, but also avoids the manufacturing difficulties caused by the overly large foil specifications, and expands the application range of the foil coil.

[0052] 2) Solve the problem of excessive current density at the end of the foil coil:

[0053] First, from the perspective of current distribution, when the single foil coil used in the low-voltage winding is divided into two parallel foil coils, the current originally concentrated in one foil coil is dispersed into the two foil coils. This dispersed current distribution makes the current density in each foil coil relatively lower, thereby reducing the difference in current density between the ends and the middle of the foil. Due to the relatively uniform distribution of current density, the "current squeeze" phenomenon is effectively suppressed, and the local overheating problem at both ends of the foil is also alleviated.

[0054] Secondly, from the perspective of magnetic field influence, the leakage magnetic field has an important influence on the current distribution within the foil-wound coil. In a single foil-wound coil, the leakage magnetic field may cause the current to concentrate at the edge of the foil, forming a "squeeze flow". However, when the single foil-wound coil used in the low-voltage winding is divided into two parallel foil-wound coils, the interaction between the two foil-wound coils and their interaction with the leakage magnetic field changes. This change helps to further disperse the current and reduce the occurrence of the "squeeze flow" phenomenon. Specifically, the two parallel foil-wound coils can be regarded as a more complex current system in which the distribution of the current is affected by multiple factors, including the mutual inductance between the foil-wound coils, the distribution of the leakage magnetic field, and the distribution law of the current itself. These factors work together to make the current more evenly distributed in the two foil-wound coils, thereby alleviating the "squeeze flow" phenomenon.

[0055] 3) Solve the manufacturing problems caused by oversized foil:

[0056] First, the first foil-wound coil 1 and the second foil-wound coil 2 are each equipped with a conductive bar. The reduction in current means that the current that the conductive bar needs to carry is also reduced accordingly, so a smaller conductive bar can be selected. A smaller conductive bar not only reduces material costs, but also reduces the space occupied by the conductive bar inside the transformer, which helps to keep the transformer small. In addition, a smaller conductive bar is also easier to bend and shape, so that a more compact connection method can be adopted, further saving space.

[0057] Secondly, using smaller conductive bars and more compact connections can also help improve the transformer's ability to withstand short circuits. When the transformer is hit by a short-circuit current, the larger current will generate larger electromagnetic forces in the conductive bars and foil coils, which may cause the foil coil structure to deform and reduce its ability to withstand short circuits. Using smaller conductive bars and more compact connections can reduce the impact of these electromagnetic forces, because smaller conductive bars have smaller cross-sectional areas, and thus generate relatively smaller electromagnetic forces. At the same time, a more compact connection method can also help improve the stability of the foil coil, making it more resistant to short-circuit current shocks.

[0058] In addition, the current flowing through the two foil-wound coils is significantly reduced compared to the original foil-wound coils, which can also reduce the power loss of the entire low-voltage winding and the temperature rise of the foil-wound coils. For details, see 1)~2 below):

[0059] 1) The secondary winding structure of the embodiment of the present application makes the current distribution in the two foil-wound coils more uniform, thereby reducing the imbalance of current density. Due to the improvement in current distribution, the magnetic field distribution inside the transformer is also optimized, and the magnetic field is more evenly distributed inside the transformer. At the same time, this structure can also effectively reduce magnetic leakage, that is, reduce the leakage of magnetic field from the inside of the transformer to the outside. The reduction in magnetic leakage means that the magnetic field is more confined inside the transformer for electromagnetic induction and energy conversion. In this way, the stray losses caused by magnetic field inhomogeneity and magnetic leakage will be significantly reduced, thereby improving its operating efficiency and reliability.

[0060] 2) After the current is dispersed to the two foil-wound coils, the heat generated by each foil-wound coil is significantly reduced compared to the original foil-wound coil, thereby reducing the temperature rise of the foil-wound coil, which helps to extend the service life of the foil-wound coil and improve the overall performance of the transformer.

[0061] In summary, the embodiment of the present application can get rid of the limitation of foil specifications on the height of the foil coil, and improve the application range of the foil coil; it can also effectively reduce the "squeeze flow" phenomenon of the foil coil, reduce the current at the end of the foil, and slow down the aging speed of the insulating material; it can also reduce the radial size of the conductive row of the foil coil, avoid the non-circular shape of the foil coil, and improve the short-circuit resistance; it can also reduce the stray loss of the foil coil and reduce the temperature rise of the foil coil. The secondary winding of the embodiment of the present application is simple in structure, easy to install, practical and reliable, which is of great significance to the long-term reliable and safe operation of the transformer.

[0062] In a possible implementation, based on any of the embodiments provided above, the wire inlet of the conductive row of the first foil-wound coil 1 and the wire outlet of the conductive row of the second foil-wound coil 2 are oriented in opposite directions, one facing upward and the other facing downward; the wire outlet of the conductive row of the first foil-wound coil 1 and the wire inlet of the conductive row of the second foil-wound coil 2 are oriented in opposite directions, one facing upward and the other facing downward. The advantages of this design are shown in 1) to 3 below):

[0063] 1) When two foil coils are connected in parallel, if the inlet and outlet positions of their conductive bars are opposite, the current distribution in the two foil coils can be more uniform. This is because when the current flows into and out of the foil coil, a specific magnetic field distribution is generated near the conductive bar. By designing in the opposite direction, these magnetic field distributions can be balanced and the current inhomogeneity can be reduced.

[0064] 2) The same winding direction and opposite conductive bar inlet and outlet positions help reduce electromagnetic interference between foil coils. When the currents in the two foil coils are in the same direction, the magnetic fields they generate are also in the same direction. By carefully designing the conductive bar inlet and outlet positions, these magnetic fields can be offset or weakened in space, thereby reducing electromagnetic interference.

[0065] 3) This design can also simplify the wiring of the equipment. By rationally arranging the locations of the conductive bar inlet and outlet, the number and length of wires can be reduced, thereby reducing manufacturing costs and installation difficulty.

[0066] In a transformer, due to the large current, the traditional single-channel low-voltage lead wire may not meet the requirements. Therefore, in a possible implementation, based on any of the embodiments provided above, the embodiment of the present application connects the conductive row lead wire 4 into several frame structures, and the low-voltage lead wires of the first foil-wound coil 1 and the second foil-wound coil 2 of each phase are firstly connected through the conductive row lead wire 4 for current convergence and then divided into two paths, and finally led out of the transformer through the bushing lead wire 5, still referring to Figure 2 .

[0067] Specifically, the conductive row leads 4 are connected into several frame structures, which play the role of current convergence. The current generated by two independent foil coils is first converged through the conductive row leads 4, and then evenly divided into two paths through these frame structures. In this way, the large current originally concentrated in one path is dispersed into two paths, thereby reducing the load of each path and improving the operating efficiency and safety of the transformer.

[0068] After the current convergence and diversion are completed, the two currents are respectively led out of the transformer through the bushing lead wires 5. The bushing lead wires 5 serve as channels for current transmission, ensuring that the current can be stably and safely transmitted to the equipment or system outside the transformer.

[0069] The reason why the method of converging first and then dividing the current is chosen instead of directly dividing the output into two paths is mainly because of current balance. Specifically, when the transformer works in a high current environment, the two foil-wound coils of its low-voltage winding are connected in parallel. Due to factors such as manufacturing tolerances and magnetic field perturbations, the currents generated by the two foil-wound coils may be unbalanced to a certain extent. By converging the current first, it can be ensured that the currents of the two foil-wound coils are balanced at the confluence point, thereby avoiding damage to the transformer caused by current imbalance. If the output is directly divided into two paths, it may aggravate the imbalance of the current and affect the normal operation of the transformer.

[0070] In addition, an embodiment of the present application also provides a transformer, comprising a low-voltage winding of any of the transformers provided above.

[0071] In a possible implementation, the magnetic core of the transformer includes: a middle iron yoke insulation; the middle iron yoke insulation is placed in the middle iron yoke part of the transformer core and is located between the first foil winding coil 1 and the second foil winding coil 2, playing a key role in effectively isolating and optimizing transformer performance.

[0072] Specifically, the middle yoke insulation is an insulating component used in transformers. The transformer core generally has upper and lower yokes and a middle iron column. The middle yoke insulation is an insulating component located at the middle yoke position of the core. The middle yoke insulation is usually made of high-insulation materials such as insulating paper, insulating board or insulating oil. It has good electrical insulation and mechanical strength. It can not only withstand the voltage and current generated by the transformer during operation, but also avoid local short circuits in the core, prevent eddy currents generated by electromagnetic induction between different lamination layers of the core from forming circulation in the yoke area, reduce eddy current losses, and ensure efficient and stable operation of the transformer.

[0073] Secondly, the middle iron yoke insulation is located between the first foil-wound coil 1 and the second foil-wound coil 2 to ensure electrical isolation between the two coils, prevent electrical short circuit between the two foil-wound coils, and ensure that the transformer can operate safely and efficiently.

[0074] In addition, the design of the middle iron yoke insulation also needs to consider the heat dissipation performance of the transformer. Because the transformer generates a lot of heat during operation, if the insulation material has poor thermal conductivity, the temperature of the foil coil will be too high, thus affecting the service life and performance of the transformer. Therefore, the above-mentioned middle iron yoke insulation usually needs to use materials with good thermal conductivity to ensure that the transformer can effectively dissipate heat.

[0075] Since the transformer generates a large amount of heat during operation, if the heat cannot be dissipated in time, the temperature of the foil coil and the insulation material will rise, thereby affecting the performance and life of the transformer. In this regard, in a possible implementation, the embodiment of the present application is designed to have an opening on the middle iron yoke insulation to ensure the smooth flow of the upper and lower oil channels of the foil coil, thereby providing a good heat dissipation channel.

[0076] Specifically, the oil passages above and below the foil-wound coil are for the cooling oil to flow through. The cooling oil plays an important role in heat dissipation in the transformer. It can transfer the heat generated by the coil to the outside of the transformer, and then dissipate the heat into the air through a radiator or natural convection. The openings in the middle iron yoke insulation ensure that the cooling oil can flow freely through the oil passages, thereby taking away more heat and improving the heat dissipation efficiency. On the contrary, if there are no openings in the middle iron yoke insulation, the cooling oil will not be able to flow smoothly through the upper and lower oil passages of the foil-wound coil, thus affecting the heat dissipation effect.

[0077] The number of openings provided on the middle iron yoke insulation can indeed be one or more, which mainly depends on the specific design of the transformer, power requirements, heat dissipation requirements, manufacturing process and other factors. For high-power transformers or transformers with high heat dissipation requirements, it is generally necessary to set multiple openings to meet the heat dissipation requirements. Multiple openings can be distributed at different positions of the middle iron yoke insulation to ensure that the cooling oil can flow more evenly through the upper and lower oil channels of the foil-wound coil to improve the heat dissipation efficiency. However, it should be noted that the number and position of the openings need to be carefully designed to ensure that they do not have an adverse effect on the electrical performance and structural strength of the transformer.

[0078] In one possible implementation, any of the transformers provided above is an offshore wind power transformer. Offshore wind power transformers are usually installed on the base or platform of an offshore wind turbine and are used to boost the electricity generated by the generator and transmit it to the power grid. Since offshore wind farms are usually located in sea areas far away from land, these transformers need to withstand extreme environmental conditions such as high humidity, high salinity, strong winds and waves, etc., so they have strict requirements such as high reliability, compact design, efficient heat dissipation, and strong short-circuit resistance. The specific description is as follows:

[0079] 1) High reliability: As offshore wind farms are located in remote locations and are difficult to maintain, once a transformer fails, the maintenance cost is extremely high and will result in a large amount of power generation loss. Therefore, offshore wind power transformers must use higher quality materials, more advanced processes, and more advanced structural designs during the design and manufacturing process to ensure long-term stable operation in harsh environments.

[0080] 2) Compact design: The space on offshore wind power platforms is limited, requiring the transformer to be as small as possible. This requires optimizing the internal structure and improving space utilization during design.

[0081] 3) Efficient heat dissipation: Offshore wind power transformers generate a lot of heat during operation, and the offshore environment is not conducive to natural heat dissipation. Therefore, an efficient cooling system is usually equipped to quickly remove the heat generated inside the transformer, ensure that its operating temperature is within a reasonable range, and prevent insulation aging and performance degradation due to overheating. At the same time, the design of the cooling system also needs to take into account the particularities of the offshore environment, such as corrosion resistance and resistance to wind and wave impact.

[0082] 4) Strong short-circuit resistance: Various electrical faults may occur in offshore wind power systems, among which short-circuit faults will generate huge short-circuit currents, causing serious impacts on transformers. Therefore, corresponding measures must be taken during the design of offshore wind power transformers to improve their short-circuit resistance.

[0083] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can be referred to each other and will not be repeated. For the transformer disclosed in the embodiment, since it includes all the contents of the aforementioned low-voltage winding embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the low-voltage winding embodiment.

[0084] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of the present application. Therefore, the embodiments of the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A low voltage winding of a transformer, characterized in that: include: A first foil-wound coil (1), a second foil-wound coil (2) and a conductive row lead (4); The first foil-wound coil (1) and the second foil-wound coil (2) are respectively used to be mounted on the upper part and the lower part of the iron core column (3) of the transformer; The first foil-wound coil (1) and the second foil-wound coil (2) are both provided with input and output wires; the input wire of the first foil-wound coil (1) and the input wire of the second foil-wound coil (2) are connected via a conductive row lead wire (4), and the output wire of the first foil-wound coil (1) and the output wire of the second foil-wound coil (2) are also connected via a conductive row lead wire (4); The first foil-wound coil (1) and the second foil-wound coil (2) have the same specifications and the same winding direction.

2. The low voltage winding of the transformer according to claim 1, characterized in that: The wire inlet of the conductive row of the first foil-wound coil (1) and the wire outlet of the conductive row of the second foil-wound coil (2) are oriented in opposite directions, one facing upwards and the other facing downwards; the wire outlet of the conductive row of the first foil-wound coil (1) and the wire inlet of the conductive row of the second foil-wound coil (2) are oriented in opposite directions, one facing upwards and the other facing downwards.

3. The low voltage winding of the transformer according to claim 1 or 2, characterized in that: The conductive row leads (4) are connected to form a plurality of frame structures, and the plurality of frame structures play a role in current convergence; the low-voltage lead wires of the first foil-wound coil (1) and the second foil-wound coil (2) of each phase are firstly connected through the conductive row leads (4) and then divided into two paths, and finally led out of the transformer through the bushing lead wires (5).

4. A transformer, characterized in that: include: A low voltage winding of a transformer as claimed in any one of claims 1 to 3.

5. The transformer according to claim 4, characterized in that: The magnetic core of the transformer comprises a middle iron yoke insulation; the middle iron yoke insulation is placed in the middle iron yoke part of the transformer core and is located between the first foil-wound coil (1) and the second foil-wound coil (2).

6. The transformer according to claim 5, characterized in that: At least one opening is provided on the middle iron yoke insulation, and the opening is used to ensure smooth flow of upper and lower oil passages of the foil-wound coil.

7. The transformer according to claim 4, characterized in that: The transformer is an offshore wind power transformer.

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