Novel double-frequency multi-voltage oil-immersed power transformer

Abstract

The invention belongs to the technical field of transformers, and particularly relates to a novel dual-frequency multi-voltage oil-immersed power transformer, which comprises a transformer body and a multi-frequency multi-voltage regulation and control system integrated in the transformer body, the multi-frequency multi-voltage regulation and control system comprises a dual-frequency control module and a voltage regulation device, the dual-frequency switching module is used for realizing dual-frequency switching and stable output under multiple voltage levels; the iron core coil composite unit comprises an iron core structure and a long circular coil structure, the iron core structure comprises a plurality of groups of silicon steel sheet units, the whole cross section of each silicon steel sheet unit is triangular, and the plurality of groups of silicon steel sheet units are laminated step by step to form an iron core module. According to the invention, the parameters of the transformer can be adjusted according to the frequency, so that the transformer can realize frequency switching of transformation, in different-frequency power supply environments, the equipment quantity investment is reduced, and meanwhile, the lamination mode is improved, and the lamination efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of transformer technology, specifically relating to a novel dual-frequency multi-voltage oil-immersed power transformer. Background Technology

[0002] With the global energy interconnection and the large-scale application of renewable energy, power systems are placing higher demands on the adaptability of transformers. On the one hand, scenarios such as cross-border grid interconnection (e.g., connecting China's 50Hz grid with Europe and the United States' 60Hz grid) and wind and solar power grid connection (with frequency fluctuations expanding to 48-62Hz) require transformers to have multi-frequency (e.g., 50Hz / 60Hz) compatibility. On the other hand, differences in voltage levels between different countries / regions and the access of distributed power sources (voltage fluctuations ±10%) require transformers to support multi-voltage level switching. Safe, reliable, high-performance, and novel dual-frequency multi-voltage transformers have become products urgently needed by users. To avoid the transformation of transformers invested in now into obsolete ones after future grid upgrades, resulting in a huge waste of resources, the new type of dual-frequency multi-voltage transformer has emerged.

[0003] However, currently, traditional oil-immersed power transformers are designed based on a single frequency, relying on a fixed number of turns and magnetic flux density to match the induced electromotive force. When the frequency changes, this may lead to insulation breakdown or equipment overload risks. The transformer body adopts a rectangular iron core and circular coil structure, resulting in a large spacing between iron core columns, a long magnetic circuit (high no-load loss), and low efficiency of iron core lamination. The large gaps are prone to hysteresis and stretching vibration, affecting long-term operational reliability. Summary of the Invention

[0004] The purpose of this invention is to provide a novel dual-frequency multi-voltage oil-immersed power transformer that can adjust transformer parameters according to frequency, enabling the transformer to switch between voltage transformation frequencies. This reduces the number of equipment required in different frequency power supply environments. At the same time, it improves the lamination method to increase lamination efficiency.

[0005] The specific technical solution adopted by this invention is as follows: A novel dual-frequency multi-voltage oil-immersed power transformer includes a transformer body and components integrated within the transformer body: A multi-frequency and multi-voltage regulation system, comprising a dual-frequency control module and a voltage regulation device, for realizing dual-frequency switching and stable output under multiple voltage levels; The iron core coil composite unit includes an iron core structure and an elongated coil structure. The iron core structure includes multiple sets of silicon steel sheet units. The cross-section of each silicon steel sheet unit is triangular, and the multiple sets of silicon steel sheet units are stacked in a step-by-step manner to form an iron core module.

[0006] In a preferred embodiment, the silicon steel sheet unit includes a first silicon steel sheet group and a second silicon steel sheet group arranged in a sequential cycle. The first silicon steel sheet group is stacked in the order of sheet type 1 to sheet type 7 to form a first step, and the size of sheet type 1 to sheet type 7 decreases sequentially. The second silicon steel sheet group is stacked in the order of sheet type 7 to sheet type 7 to form a second step. The structural combination formed by the first silicon steel sheet group and the second silicon steel sheet group is an equilateral or scalene triangle.

[0007] In a preferred embodiment, the dual-frequency control module includes at least two automatic frequency switching controls, and the dual-frequency control module integrates a frequency detection unit and an adaptive adjustment unit. The frequency detection unit detects the current frequency by sampling the power grid voltage signal; The adaptive adjustment unit adjusts parameters based on the detected frequency and according to the basic formula of the transformer to reduce potential fluctuations.

[0008] In a preferred embodiment, the two frequencies are 50Hz and 60Hz, respectively.

[0009] In a preferred embodiment, the voltage regulating device includes a primary winding and a secondary winding. The primary winding has several taps, dividing the winding into an even number of series-parallel segments and several tap segments. The taps of the series-parallel segments are connected to a series-parallel switch, and the taps of the tap segments are connected to a tap switch. The series-parallel segments are connected in series or in parallel by adjusting the series-parallel switch, and the number of turns of the tap segments is adjusted by adjusting the tap switch. Combined with star-delta connection switching, the transformer output voltage remains constant during high and low voltage operation.

[0010] In a preferred embodiment, the elongated coil structure includes a high-voltage coil and a low-voltage coil. The interlayer insulation of the high-voltage coil is made of AMA material to reduce the thickness of the interlayer insulation. The low-voltage coil is wound with copper foil.

[0011] In a preferred embodiment, the oil channels between the coil layers are eliminated in the short axis direction of the elongated coil to make the coil flatter.

[0012] In a preferred embodiment, the device body is treated with a vacuum drying process.

[0013] The technical effects achieved by this invention are as follows: the multi-frequency and multi-voltage regulation system can dynamically adjust the coil parameters of the transformer according to the frequency to stabilize the induced electromotive force and achieve stable output at different frequencies. Most importantly, by supporting dual-frequency switching, it can adapt to different power grid environments, reducing the cost of equipment replacement or modification due to frequency mismatch. At the same time, with the voltage regulation device, the transformer can keep the output voltage of the transformer stable when operating at high and low voltage, thereby improving the stability of the transformer. This allows the transformer to cover multiple voltage levels and meet the needs of power grid upgrades or changes in user demand for stable voltage output.

[0014] This invention reduces magnetic resistance within the iron core by precisely controlling the stacking sequence and position of silicon steel sheets, thereby lowering no-load losses and noise. In this stacking method, the core stacking process is divided into seven steps, each with specific requirements for the arrangement and stacking of silicon steel sheets. This allows for more effective utilization of the properties of silicon steel sheets, increasing the magnetic flux density of the iron core while reducing additional losses caused by seams. Furthermore, this stacking method also improves the mechanical strength of the iron core, making it more stable during operation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the silicon steel sheet unit of the present invention; Figure 2 This is a schematic diagram of the series connection of the parallel and serial segments of the present invention; Figure 3 This is a schematic diagram of the parallel connection of the series and parallel segments of the present invention; Figure 4 This is a schematic diagram of the star-corner connection of the present invention; Figure 5 This is a schematic diagram of the elongated circular coil structure of the present invention; Figure 6 This is a simplified diagram of the interlayer insulation placement and number of turns of the elongated circular coil structure of the present invention. Detailed Implementation

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0018] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in a preferred embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0019] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth. Example

[0020] Please see the appendix Figures 1 to 6 As shown, this is the first embodiment of the present invention, a novel dual-frequency multi-voltage oil-immersed power transformer, including a transformer body and components integrated within the transformer body: A multi-frequency and multi-voltage regulation system, comprising a dual-frequency control module and a voltage regulation device, for realizing dual-frequency switching and stable output under multiple voltage levels; The iron core coil composite unit includes an iron core structure and an elongated coil structure. The iron core structure includes multiple sets of silicon steel sheet units. The cross-section of each silicon steel sheet unit is triangular, and the multiple sets of silicon steel sheet units are stacked in a step-by-step manner to form an iron core module.

[0021] In the above embodiments, the multi-frequency and multi-voltage control system can dynamically adjust the transformer coil parameters according to the frequency to stabilize the induced electromotive force and achieve stable output at different frequencies. Most importantly, by supporting dual-frequency switching, it can adapt to different power grid environments, reducing the cost of equipment replacement or modification due to frequency mismatch. At the same time, with the voltage regulation device, the transformer can keep the output voltage of the transformer stable when operating at high and low voltage, thereby improving the stability of the transformer. This allows the transformer to cover multiple voltage levels and meet the stable voltage output when the power grid is upgraded or user needs change. In addition, by sequentially arranging multiple sets of silicon steel sheet units, leakage flux at the joints can be reduced and magnetic flux density can be increased. Combined with the long round coil structure, the center distance of the iron core column can be shortened, reducing the amount of iron core used and no-load loss.

[0022] It should be noted that the device body is treated with a vacuum drying process, and the drying time is shorter than that of traditional processes. Most importantly, vacuum drying can effectively improve the electrical insulation performance of the product, while also shortening the drying time of the device body and effectively reducing the energy consumption of product manufacturing.

[0023] Furthermore, for a better explanation of the core structure, please refer to [link / reference]. Figure 1 The silicon steel sheet unit includes a first silicon steel sheet group and a second silicon steel sheet group arranged in a sequential cycle. The first silicon steel sheet group is stacked in the order of sheet type 1 to sheet type 7 to form the first step, and the size of sheet type 1 to sheet type 7 decreases sequentially. The second silicon steel sheet group is stacked in the order of sheet type 7 to sheet type 7 to form the second step. The structure formed by the stacking of the first silicon steel sheet group and the second silicon steel sheet group is an equilateral or scalene triangle, wherein sheet type 1 to sheet type 7 are the first sheet type 1 to the seventh sheet type 7, and are arranged in numerical order in between.

[0024] Specifically, transformer cores in the industry all adopt a step-step lamination method. Initially, most were transverse step-step structures. In recent years, with the development of automated lamination, longitudinal step-step structures have gradually emerged. Longitudinal lamination is superior to transverse lamination in terms of lamination accuracy and insulation performance. To further fully utilize the excellent quality of cold-rolled silicon steel sheets, we now commonly use 45-degree oblique joints, that is, the lamination joints between each layer of silicon steel sheets are staggered longitudinally or transversely. In other words, when the core is laminated in a step-step manner, the stepping method is from type 1 to type 2. The wafers are stacked in an alternating sequence of type 2-3-4-5-6-7, forming a cycle. The next cycle follows the same sequence: type 1-2-3-4-5-6-7. Therefore, all shapes are right-angled triangles. However, regardless of the horizontal or vertical stacking method, the overall efficiency is low, as only a single cycle of wafers can be inserted or stacked at a time, resulting in poor stacking efficiency. Therefore, this application employs a first silicon steel sheet group and a second silicon steel sheet group, significantly improving stacking efficiency.

[0025] Specifically, the dimensions of the first piece type 1, the second piece type 2, the third piece type 3, the fourth piece type 4, the fifth piece type 5, the sixth piece type 6, and the seventh piece type 7 decrease sequentially. The following steps are then employed: First, a silicon steel sheet unit with multiple or more sets of silicon steel sheet combinations is pre-set, and each set of silicon steel sheet units includes a first silicon steel sheet group and a second silicon steel sheet group arranged in a sequential cycle. Second, the first silicon steel sheet group is stacked sequentially to form the first step, and the second silicon steel sheet group is stacked to form the second step. Third, the first silicon steel sheet group and the second silicon steel sheet group are combined into an equilateral triangle structure or an scalene triangle structure; then, the process is repeated in the same way as the first silicon steel sheet group and the second silicon steel sheet group. Fourth, the equilateral or scalene triangular structures are stacked to form the transformer core structure.

[0026] The above method is the seven-step longitudinal lamination technology. It reduces the magnetic resistance inside the core by precisely controlling the lamination sequence and position of the silicon steel sheets, thereby reducing no-load losses and noise. In this lamination method, the core lamination process is divided into seven steps, each with specific requirements for the arrangement and stacking of the silicon steel sheets. The advantage of the seven-step longitudinal lamination is that it can more effectively utilize the characteristics of silicon steel sheets, increase the magnetic flux density of the core, and reduce additional losses caused by seams. Furthermore, this lamination method can improve the mechanical strength of the core, making it more stable during operation. Using a seven-step single-sheet lamination method effectively reduces gaps, making the sheets closer together, effectively reducing magnetic leakage, increasing magnetic flux, and thus reducing the no-load losses of the core. At the same time, the seven-step single-sheet lamination method greatly improves production efficiency, thereby reducing production costs. This seven-step process structure aims to improve lamination accuracy, reduce the probability of errors in manual lamination, and increase work efficiency.

[0027] In a preferred embodiment, the dual-frequency control module includes at least two frequency automatic switching controls, namely 50Hz and 60Hz, and the dual-frequency control module integrates a frequency detection unit and an adaptive adjustment unit. The frequency detection unit detects the current frequency by sampling the power grid voltage signal; The adaptive adjustment unit adjusts parameters based on the detected frequency and according to the basic formula of the transformer to reduce potential fluctuations.

[0028] Specifically, based on the above method, the current frequency is monitored by a frequency detection unit, and then the adaptive adjustment unit adjusts the parameters according to the basic transformer formula U=4.44fNBS (where U is the induced electromotive force, f is the power supply frequency, N is the number of coil turns, B is the magnetic flux density, and S is the core cross-sectional area). The principle is that when the frequency f changes, other parameters also need to be adjusted accordingly to ensure the normal operation and performance of the transformer, thereby achieving frequency switching and reducing switching fluctuations after frequency changes. In other words, using dual frequencies can solve the problem of reducing the number of devices required in environments supplying power at different frequencies, eliminating the need to switch between multiple power sources. Furthermore, another advantage of dual-frequency transformers is that by selecting the higher frequency for operation, according to the basic transformer formula... (IW is the rated ampere-turns, f is the frequency, et is the turn potential, Hk is the reactance height, and Kx is the reactance coefficient) This represents the total area of ​​equivalent magnetic leakage. (where f is the Rockwell coefficient), where a higher frequency (f) indicates a greater transformer impedance and stronger short-circuit withstand capability. In other words, a high-frequency transformer operates in the high-frequency range, and its frequency response is typically wider than that of a low-frequency transformer, enabling it to transmit a wider range of signal frequencies, making it suitable for broadband applications. Because high-frequency transformers operate at high frequencies, signals can pass through the windings quickly, allowing the transformer to respond to signal changes more rapidly and exhibiting faster dynamic response capabilities. Therefore, this invention, by incorporating a dual-frequency control module, enables traditional low-frequency transformers to switch to high frequencies as needed, improving response capability. The table below shows the current and voltage changes under dual-frequency conditions.

[0029]

[0030] As a specific embodiment of this application, the voltage regulating device includes a primary winding and a secondary winding. The primary winding has several taps, dividing the winding into an even number of series-parallel segments and several tap segments. The taps of the series-parallel segments are connected to a series-parallel switch, and the taps of the tap segments are connected to a tap switch. The series-parallel segments are connected in series or in parallel by adjusting the series-parallel switch, and the number of turns of the tap segments is adjusted by adjusting the tap switch. Combined with star-delta connection switching, the output voltage of the transformer is kept constant when operating at high and low voltage.

[0031] The multi-voltage regulation function is achieved through the synergistic action of series-parallel sections, tap sections, series-parallel switches, tap switches, and star-delta connections. Specifically, by adjusting the total number of turns or the connection method of the primary winding, the voltage ratio of the transformer is changed. Tap sections are divided according to a fixed turns difference. By switching tap switches to connect or disconnect a certain tap section, the total number of turns in the winding is changed. Then, by disconnecting or connecting some tap sections, the number of turns (N) in the winding can be flexibly adjusted, achieving fine voltage regulation. The regulation mechanism is based on the tap sections being divided according to a fixed turns difference (N). Dividing the winding into sections of 5 turns each, the total number of turns is directly changed by switching a tap switch to connect or disconnect a certain tap section (e.g., the original number of turns is 200, and after disconnecting one section of 5 turns, it becomes 195 turns). According to the formula U=4.44fNBS (where U is the induced electromotive force, f is the power supply frequency, N is the number of coil turns, B is the magnetic flux density, and S is the core cross-sectional area), the change in the number of turns will linearly affect the induced electromotive force (U), thereby achieving fine-tuning of the voltage. This adapts to dynamic scenarios such as distributed power supply access and ensures stable output voltage fluctuations. The tap switch supports switching between star (Y) and delta (Δ) winding connection methods, further expanding the voltage regulation coverage. Specifically, a star (Y) connection is suitable for high-voltage input scenarios (such as 35kV); a delta (Δ) connection is suitable for low-voltage input scenarios (such as 10kV). Combined with tap changer switching and connection method switching, the transformer can cover a wider input voltage range (such as 35kV-Y connection + tap changer fine-tuning, 10kV-Δ connection + tap changer fine-tuning), meeting the stable output requirements of multiple voltage levels (35kV / 10kV / 6kV). For details regarding the tap changer and adjustment process, please refer to our published patent, patent publication number CN119964961A, entitled "A Transformer High-Voltage Tap Changer and High-Voltage Lead Wiring Method," which will not be elaborated upon here.

[0032] In addition to the aforementioned tap changers, this application can also utilize a combination of electronic switching and on-load tap changer technology to ensure uninterrupted adjustment: replacing traditional mechanical switches with electronic switches avoids the delays of mechanical switching, making it suitable for scenarios with rapid frequency / voltage fluctuations, such as wind and solar power grid connection. On-load tap changers support adjustment under load conditions (traditional off-load tap changers require power disconnection), ensuring the continuity of power supply from the grid.

[0033] The primary winding is divided into an even number of series-parallel segments (e.g., 2 segments, 4 segments, etc.). Each segment has the same or proportional number of turns. The taps of these segments are connected to a series-parallel switch, allowing for either series or parallel connection. In series connection, all segments are connected end-to-end. This increases the number of turns in the primary winding, increasing the voltage ratio, suitable for high-voltage input scenarios (e.g., 10kV grids). Increasing the number of primary turns reduces the secondary output voltage, preventing overvoltage. In parallel connection, all segments are connected end-to-end. Since the voltage is the same in parallel, segments with the same number of turns have a total number of turns equal to the number of turns in a single segment. This decreases the number of turns in the primary winding, reducing the voltage ratio, suitable for low-voltage input scenarios. Reducing the number of primary turns increases the secondary output voltage, preventing undervoltage.

[0034] Furthermore, the elongated circular coil structure effectively reduces the lateral dimensions of the core, thereby reducing its weight. At the same magnetic flux density, this weight reduction translates to lower no-load losses. The elongated circular coil structure includes a high-voltage coil and a low-voltage coil. The high-voltage coil uses AMA material for interlayer insulation to reduce insulation thickness; the low-voltage coil is wound with copper foil, significantly reducing the space occupied by insulation material and improving the utilization rate of space within the core window. This shortens the center-to-center distance of the core columns, reduces core material usage, and lowers no-load losses. It also reduces copper material usage. Additionally, the elongated circular coil eliminates interlayer oil channels along its short axis, making the coil flatter, further shortening the center-to-center distance of the core columns, reducing core material usage, lowering no-load losses, and also reducing product noise.

[0035] The working principle of this invention is as follows: Vacuum drying technology improves the electrical insulation performance of the product while effectively shortening drying time and reducing energy consumption. The seven-step longitudinal lamination technology, through precise control of the lamination sequence and position of the silicon steel sheets, significantly reduces magnetic reluctance and no-load loss, thereby improving lamination efficiency and mechanical strength. The dual-frequency control module supports automatic switching between 50Hz and 60Hz, optimizing transformer parameter adjustment and improving high-frequency short-circuit withstand capability and dynamic response speed. The voltage regulation device, through flexible switching between series-parallel sections, tap sections, and star-delta connections, achieves stable output and fine adjustment across multiple voltage levels. The long round coil structure uses advanced AMA material and copper foil winding, effectively reducing core size and weight, lowering no-load loss and noise, while improving space utilization.

[0036] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A novel dual-frequency multi-voltage oil-immersed power transformer, characterized in that, Including the vessel body, and what is integrated within the vessel body: A multi-frequency and multi-voltage regulation system, comprising a dual-frequency control module and a voltage regulation device, for realizing dual-frequency switching and stable output under multiple voltage levels; The iron core coil composite unit includes an iron core structure and an elongated coil structure. The iron core structure includes multiple sets of silicon steel sheet units. The cross-section of each silicon steel sheet unit is triangular, and the multiple sets of silicon steel sheet units are stacked in a step-by-step manner to form an iron core module.

2. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The silicon steel sheet unit includes a first silicon steel sheet group and a second silicon steel sheet group arranged in a sequential cycle. The first silicon steel sheet group is stacked in the order of sheet type 1 to sheet type 7 to form the first step, and the size of sheet type 1 to sheet type 7 decreases sequentially. The second silicon steel sheet group is stacked in the order of sheet type 7 to sheet type 7 to form the second step. The structure formed by the stacking of the first silicon steel sheet group and the second silicon steel sheet group is an equilateral or scalene triangle.

3. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The dual-frequency control module includes automatic switching control for at least two frequencies, and integrates a frequency detection unit and an adaptive adjustment unit. The frequency detection unit detects the current frequency by sampling the power grid voltage signal; The adaptive adjustment unit adjusts parameters based on the detected frequency and according to the basic formula of the transformer to reduce potential fluctuations.

4. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The two frequencies are 50Hz and 60Hz, respectively.

5. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The voltage regulating device includes a primary winding and a secondary winding. The primary winding has several taps, dividing the winding into an even number of series-parallel sections and several tap sections. The taps of the series-parallel sections are connected to a series-parallel switch, and the taps of the tap sections are connected to a tap switch. The series-parallel sections are connected in series or in parallel by adjusting the series-parallel switch, and the number of turns of the tap sections is adjusted by adjusting the tap switch. Combined with star-delta connection switching, the transformer output voltage remains constant during high and low voltage operation.

6. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The elongated coil structure includes a high-voltage coil and a low-voltage coil. The high-voltage coil uses AMA material for interlayer insulation to reduce the thickness of the interlayer insulation. The low-voltage coil is wound with copper foil.

7. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The oil channels between the coil layers are removed along the short axis of the long circular coil to make the coil flatter.

8. The novel dual-frequency multi-voltage oil-immersed power transformer according to claim 1, characterized in that: The device body is treated with a vacuum drying process.

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