Offshore photovoltaic transformer and photovoltaic system

Abstract

The invention discloses an offshore photovoltaic transformer and a photovoltaic system. The transformer comprises a high-voltage winding, a low-voltage winding and a composite insulation system, the high-voltage winding is arranged at one end of a bottom plate of the transformer oil tank and adopts an entangled coil structure; the low-voltage winding is arranged at the other end of the bottom plate of the transformer oil tank and adopts a double split coil structure; the composite insulation system comprises a multi-stage insulation isolation assembly, the multi-stage insulation isolation assembly is arranged between the high-voltage winding and the low-voltage winding, and a plurality of heavy oil gap intervals are arranged in the multi-stage insulation isolation assembly so as to form a multi-step type insulation barrier. The transformer has the characteristics of ultra-large voltage transformation ratio, double-split low-voltage input and the like, and can at least solve the problem that an existing transformer is difficult to meet the requirements of an offshore photovoltaic power station in the aspects of voltage conversion, power supply reliability and the like.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, specifically relating to a transformer and photovoltaic system for offshore photovoltaic applications. Background Technology

[0002] Offshore photovoltaic (PV) power plants have become a key development area in the new energy sector due to their advantages such as not being limited by land resources, stable sunlight conditions, and high power generation efficiency. In the power system of an offshore PV power plant, the transformer, as the core equipment for power conversion and transmission, directly affects the power generation efficiency, operational safety, and service life of the entire power plant.

[0003] Currently, offshore photovoltaic (PV) power plants face multiple technical challenges in their power conversion process. On one hand, the voltage output from the inverter of the PV array is typically low-voltage (0.8kV), directly fed into the 110kV high-voltage grid. This necessitates transformers with a large voltage conversion capability. However, conventional transformers have limited voltage ratios, making direct conversion between 110kV and 0.8kV difficult. Power transmission often requires a multi-stage transformation process: low voltage → medium voltage → high voltage. This multi-stage conversion not only increases the number of devices and system complexity but also reduces overall power generation efficiency due to energy losses at multiple stages, contradicting the "high efficiency and energy saving" design philosophy of offshore PV power plants. On the other hand, offshore PV power plants employ a modular layout with multiple PV subarrays operating in parallel, placing special demands on the low-voltage input structure of the transformer. Traditional transformers often have a single-circuit design on the low-voltage side. A failure in one PV subarray can easily affect the entire power supply system, failing to meet the reliability requirements of PV power plants.

[0004] Furthermore, offshore photovoltaic power station platforms are exposed to high salt spray, high humidity, and strong ultraviolet radiation environments for extended periods, making the casings and components of conventional transformers prone to corrosion and aging. Offshore photovoltaic power station platforms are also subject to continuous multi-directional vibration loads from wave impacts, wind turbine vibrations, and photovoltaic support swaying. The fixed structures of conventional transformers are insufficient to effectively buffer these vibrations, easily leading to loosening of internal windings, core displacement, or wear of insulating components, resulting in equipment failure. In terms of safety and environmental performance, traditional transformers often use mineral oil as the insulating coolant, which has an extremely low biodegradability rate. Leaks can cause serious pollution to the marine ecosystem, failing to meet the stringent regulations of the International Maritime Organization (IMO) regarding marine environmental protection. Finally, the windings, cores, and clamping structures of conventional transformers have insufficient short-circuit resistance, making them susceptible to fatal failures such as winding deformation and core damage under short-circuit current impacts. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the existing technology by providing a transformer and photovoltaic system for offshore photovoltaic power generation, which has the characteristics of ultra-large voltage ratio and dual-split low-voltage input, and can at least solve the problem that existing transformers are unable to meet the requirements of offshore photovoltaic power plants in terms of voltage conversion and power supply reliability.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0007] According to a first aspect of the present invention, a transformer for marine photovoltaic applications is provided, comprising a high-voltage winding, a low-voltage winding, and a composite insulation system, wherein:

[0008] The high-voltage winding is located at one end of the transformer tank bottom plate and adopts a tangled coil structure;

[0009] The low-voltage winding is located at the other end of the transformer tank bottom plate and adopts a double-split coil structure;

[0010] The composite insulation system includes a multi-level insulation isolation component, which is located between the high-voltage winding and the low-voltage winding. The multi-level insulation isolation component has multiple oil gap intervals to form a multi-step insulation barrier.

[0011] Optionally, the low-voltage winding includes a low-voltage insulating cylinder, an upper low-voltage coil, a middle insulating ring, a lower low-voltage coil, and an outer support bar. The low-voltage insulating cylinder has a coil mold. The upper low-voltage coil is wound around the upper part of the coil mold, the middle insulating ring is fitted around the middle part of the coil mold, and the lower low-voltage coil is wound around the lower part of the coil mold. The top of the upper low-voltage coil and the bottom of the lower low-voltage coil each have a copper busbar. Both the upper and lower low-voltage coils are made of copper foil, and the length of the copper foil in the upper low-voltage coil is the same as that in the lower low-voltage coil. The outer support bar is located around the upper and lower low-voltage coils. The outer support bar has slots in which polyester tape is bound to bind the components of the low-voltage winding together.

[0012] Optionally, the thickness of the central insulating ring is ≥40mm.

[0013] Optionally, the low-voltage winding has corner rings at both ends, which are made of semiconductor carbon black paper and thermally modified paper.

[0014] Optionally, the high-voltage winding includes a high-voltage insulating cylinder and a high-voltage coil; the high-voltage coil is located outside the high-voltage insulating cylinder, the high-voltage coil adopts a center-entry wire, and the high-voltage coil includes a high-voltage upper coil and a high-voltage lower coil.

[0015] Optionally, a small corner ring is provided at the beginning and end of the high-voltage coil, and the small corner ring is made of E-grade DDP heat-resistant paper;

[0016] The high-voltage insulating cylinder is equipped with large angle rings at both ends, which are made of Grade A sulfate pulp.

[0017] Optionally, the multi-level insulation isolation assembly includes multiple high- and low-voltage oil channels and multiple high- and low-voltage enclosures; the multiple high- and low-voltage oil channels and multiple high- and low-voltage enclosures are alternately arranged, and the high-voltage insulation cylinder is adjacent to the high- and low-voltage enclosures, so that the distance between the high-voltage winding and the low-voltage winding is divided into multiple oil gap intervals.

[0018] Optionally, the oil passage between high and low pressure is made of support bars made of F-grade heat-resistant EPGC203 material.

[0019] Optionally, the partition between the high and low voltage sections and the high voltage insulation cylinder are both made of Grade A conventional extra-hard cardboard T4.

[0020] Optionally, the composite insulation system also includes a low-voltage oil channel, which is located inside the low-voltage winding and is made of support strips of F-grade heat-resistant EPGC203 material bonded to E-grade DDP heat-resistant paper.

[0021] Optionally, the transformer uses natural ester insulating liquid with an ignition point ≥320℃ as coolant, and the transformer's oil conservator is a square capsule oil conservator with an acrylic elastic capsule inside.

[0022] Optionally, both the transformer oil tank and the square capsule oil conservator are coated with a salt spray-proof and UV-resistant coating.

[0023] Optionally, the transformer also includes a vibration damping device, which is located between the high-voltage winding and the bottom plate of the transformer tank and between the low-voltage winding and the bottom plate of the transformer tank.

[0024] Optionally, the shock absorption device has a three-stage shock absorption structure, which includes an insulating cardboard, a first paper groove, a second paper groove, a shock-absorbing pad, and a cardboard; the second paper groove is disposed on the insulating cardboard, the first paper groove is disposed on the second paper groove, and the shock-absorbing pad is disposed inside the first paper groove; the cardboard is disposed at the bottom of the shock-absorbing pad, between the shock-absorbing pad and the first paper groove.

[0025] According to a second aspect of the present invention, a marine photovoltaic system is provided, comprising the above-mentioned marine photovoltaic transformer.

[0026] The transformer and photovoltaic system for marine photovoltaic applications of the present invention have the following advantages compared to the prior art:

[0027] 1) By optimizing the high-voltage winding structure and the low-voltage winding structure, and setting up a composite insulation system, it has the characteristics of ultra-large voltage transformation ratio and dual-split low-voltage input. It can realize the direct conversion of 110kV voltage to an ultra-large span transformation ratio of 1.14~0.69kV. Moreover, this direct conversion structure can greatly reduce the number of equipment and system complexity, and also reduce the overall power generation efficiency due to energy loss in multiple links.

[0028] 2) The low-voltage winding has a double-split coil structure and adopts a dual-circuit design. When a photovoltaic subarray fails, it does not affect the entire power supply system, thus meeting the reliability requirements of photovoltaic power station power supply.

[0029] 3) By using natural ester insulating liquid as coolant, the biodegradability rate is ≥97%, the ignition point is ≥320℃, and the auto-ignition temperature is ≥400℃, which not only meets environmental protection requirements but also improves fire resistance and safety.

[0030] 4) By installing a square capsule oil tank on the top of the transformer oil tank, with an acrylic elastic capsule inside, the capsule completely isolates the natural ester insulating liquid from the air, preventing moisture and impurities from entering the square structure. Compared with the traditional round oil tank, the space utilization rate can be increased by up to 30%, which can be adapted to the compact installation space of offshore platforms.

[0031] 5) By applying a coating that resists salt spray and ultraviolet radiation, the weather resistance of the transformer in the harsh marine environment can be greatly improved, extending the service life of the equipment.

[0032] 6) By installing shock absorption devices, multiple vibration loads on the offshore platform can be effectively buffered, preventing component loosening and insulation wear, and ensuring the reliability of equipment operation.

[0033] 7) By optimizing the structure of high-voltage winding, low-voltage winding, core and clamps, for example, the high-voltage winding adopts a tangled continuous winding process, and the axial compressive strength of the winding is ≥50MPa, which can improve the ability to resist sudden short circuits, improve the transformer's fault resistance, and ensure the safe operation of the offshore photovoltaic system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the internal structure of a transformer for offshore photovoltaic applications in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the internal structure of a transformer for offshore photovoltaic applications, facing the high-voltage side, in an embodiment of the present invention.

[0036] Figure 3 This is a schematic diagram of the internal structure of a transformer for offshore photovoltaic applications, facing the low-voltage side, in an embodiment of the present invention.

[0037] Figure 4This is a wiring diagram of a transformer for offshore photovoltaic applications in an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the low-voltage winding in an embodiment of the present invention;

[0039] Figure 6 This is a front view of the low-pressure insulating cylinder in an embodiment of the present invention;

[0040] Figure 7 This is a top view of the low-voltage insulating cylinder in an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the central insulating ring in an embodiment of the present invention;

[0042] Figure 9 This is a schematic diagram of a multi-level insulation isolation component in an embodiment of the present invention;

[0043] Figure 10 for Figure 9 An enlarged schematic diagram of the letter I in the diagram;

[0044] Figure 11 This is a schematic diagram of the copper foil in an embodiment of the present invention;

[0045] Figure 12 for Figure 9 An enlarged schematic diagram of M in the diagram;

[0046] Figure 13 This is a schematic diagram of the large corner ring in an embodiment of the present invention;

[0047] Figure 14 This is a front view of the shock absorption device in an embodiment of the present invention;

[0048] Figure 15 This is a top view of the shock absorption device in an embodiment of the present invention;

[0049] Figure 16 This is a side view of the shock absorption device in an embodiment of the present invention;

[0050] Figure 17 This is a left view of the external structure of the transformer for offshore photovoltaic use in an embodiment of the present invention;

[0051] Figure 18 This is a right view of the external structure of the transformer used for offshore photovoltaics in an embodiment of the present invention.

[0052] In the diagram: 1. Iron core; 4. High-voltage upper coil; 5. High-voltage lower coil; 6. Iron core grounding lead; 7. Clamp grounding lead; 8. Body pressure plate; 9. Oil tank positioning plate; 10. Upper pressure plate; 11. Lower support plate; 12. Vibration damping device;

[0053] 21. Low-voltage insulating cylinder; 22. Upper low-voltage coil; 23. Middle insulating ring; 24. Lower low-voltage coil; 25. Outer support bar; 26. Positioning and mounting hole; 27. Copper foil;

[0054] 31. Low-pressure oil passage; 311. EPGC203 material; 312. DDP heat-resistant paper; 32. Oil passage between high and low pressure; 33. Enclosure between high and low pressure; 34. High-voltage insulating cylinder; 35. Large angle ring; 351. Sulfate pulp; 36. Small angle ring; 37. Angle ring;

[0055] 51. Insulating cardboard; 52. First paper tray; 53. Second paper tray; 54. Shock-absorbing rubber pad; 55. Cardboard;

[0056] 61. Oil tank; 62. Grounding bushing; 63. Dehumidifier. Detailed Implementation

[0057] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0058] It is understood that the specific embodiments and accompanying drawings described herein are merely for explaining the invention and are not intended to limit the invention.

[0059] It is understood that, without conflict, the various embodiments and features in the embodiments of the present invention can be combined with each other.

[0060] It is understood that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, while the parts unrelated to the present invention are not shown in the drawings.

[0061] It is understood that each unit or module involved in the embodiments of the present invention may correspond to only one entity structure, or may be composed of multiple entity structures, or multiple units or modules may be integrated into one entity structure.

[0062] It is understood that, without conflict, the functions and steps marked in the flowcharts and block diagrams of this invention may occur in a different order than that marked in the accompanying drawings.

[0063] To address the numerous problems with existing transformers in terms of voltage ratio and low-voltage structure that make them unsuitable for the special operating environment and technical requirements of offshore photovoltaic power plants, this invention provides a transformer for offshore photovoltaic applications, comprising a high-voltage winding, a low-voltage winding, and a composite insulation system, wherein:

[0064] The high-voltage winding is located at one end of the transformer tank bottom plate and adopts a tangled coil structure;

[0065] The low-voltage winding is located at the other end of the transformer tank bottom plate and adopts a double-split coil structure;

[0066] The composite insulation system includes a multi-level insulation isolation component, which is located between the high-voltage winding and the low-voltage winding. The multi-level insulation isolation component has multiple oil gap intervals to form a multi-step insulation barrier between the high-voltage winding and the low-voltage winding.

[0067] Furthermore, the present invention also discloses a marine photovoltaic system, which includes the above-described marine photovoltaic transformer.

[0068] The transformer and photovoltaic system for offshore photovoltaic applications of the present invention optimize the high-voltage winding structure and the low-voltage winding structure, and set up a composite insulation system, thereby possessing features such as ultra-large voltage transformation ratio and double-split low-voltage input. It can directly convert 110kV voltage to an ultra-large span transformation ratio of 1.14~0.69kV, which can at least solve the problem that existing transformers are difficult to meet the requirements of offshore photovoltaic power stations in terms of voltage conversion and power supply reliability.

[0069] Example 1

[0070] like Figures 1-18 As shown, this embodiment discloses a transformer for offshore photovoltaic applications, including a high-voltage winding, a low-voltage winding, and a composite insulation system, wherein:

[0071] The high-voltage winding is located at one end of the transformer tank bottom plate and adopts a tangled coil structure, that is, it adopts a tangled continuous winding process, with an input voltage of 110kV.

[0072] The low-voltage winding is located at the other end of the transformer tank bottom plate and adopts a double-split coil structure. The input voltage of each coil is 1.14~0.69kV.

[0073] The composite insulation system includes a multi-level insulation isolation component, which is located between the high-voltage winding and the low-voltage winding. The multi-level insulation isolation component has multiple oil gap intervals to form a multi-step insulation barrier between the high-voltage winding and the low-voltage winding.

[0074] like Figure 4 As shown, the connection group of this transformer is YNd11-d11.

[0075] In this transformer, the above settings enable the direct conversion of 110kV voltage to an ultra-large span ratio of 1.14~0.69kV, eliminating intermediate transformation stages and reducing power loss and system complexity.

[0076] Meanwhile, by optimizing the low-voltage winding structure, it can be adapted to the modular layout of photovoltaic subarrays, improving power supply redundancy and stability. Generally speaking, this type of high-ratio transformer with a direct current conversion structure has at least the following characteristics: large low-voltage current; high high-voltage and low low-voltage; extremely large potential difference between the high-voltage and low-voltage windings; highly concentrated and extremely uneven electric field; and is extremely prone to insulation breakdown.

[0077] By optimizing the high-voltage winding structure, the capacitance distribution inside the high-voltage winding can be improved, thereby making the voltage distribution more uniform under lightning strikes or switching overvoltages and preventing excessive local voltage. By setting up a composite insulation system, multiple stepped insulation barriers are formed between the high-voltage winding and the low-voltage winding. This not only reliably undertakes the task of radial and axial insulation, but also transforms the sharp electric field at the end into a gentle arc-shaped electric field, solving the problem of electric field concentration.

[0078] In some implementations, such as Figure 1 , Figures 5-8 As shown, the low-voltage winding includes a low-voltage insulating cylinder 21, an upper low-voltage coil 22, a middle insulating ring 23, a lower low-voltage coil 24, and an outer support bar 25. The low-voltage insulating cylinder 21 has a coil mold. The upper low-voltage coil 22 is wound around the upper part of the coil mold, the middle insulating ring 23 is fitted around the middle part of the coil mold, and the lower low-voltage coil 24 is wound around the lower part of the coil mold. The top of the upper low-voltage coil 22 and the bottom of the lower low-voltage coil 24 are respectively provided with lead-in copper busbars. The low-voltage leads have low voltage and high current, and are led out from the upper and lower clamps through the lead-in copper busbars, which can be kept away from the high-voltage winding coil (in this transformer, the high and low voltage leads are connected separately). The voltage potential difference is nearly 100kV. According to electric field theory, E=U / d, the closer the two are, the stronger the local non-uniform electric field, the greater the local discharge, and the easier it is to break down. Both the low-voltage upper coil 22 and the low-voltage lower coil 24 are made of copper foil, which is the first time that copper foil coils have been used in a 110kV transformer. The length of the copper foil in the low-voltage upper coil 22 is the same as the length of the copper foil in the low-voltage lower coil 24. The outer support bar 25 is set on the periphery of the low-voltage upper coil 22 and the low-voltage lower coil 24. The outer support bar 25 has a slot, and polyester tape is tied in the slot to bind the components in the low-voltage winding together.

[0079] Specifically, the low-voltage insulating cylinder 21 is provided with positioning mounting holes 26. The coil mold is firmly fixed and installed through these positioning mounting holes 26, and the two fit tightly together without gaps or looseness. The thickness of the middle insulating ring 23 is ≥40mm. The low-voltage insulating cylinder 21 is also provided with copper busbar slots. The first copper busbars are set at the top of the upper low-voltage coil 22 and the bottom of the lower low-voltage coil 24 by welding or other methods. Sharp corners and burrs are welded off according to process requirements to prevent damage to the insulation material and to avoid electric field concentration that could cause partial discharge. After wrapping, the first copper busbars are respectively embedded in the copper busbar slots on the low-voltage insulating cylinder 21. When winding the upper low-voltage coil 22 and the lower low-voltage coil 24, align the upper low-voltage coil 22 and the lower low-voltage coil 24 and adjust the tension to be consistent. Divide the insulation layers into several reels according to the number of sheets required in the drawing. Place the paper reels on the automatic winding machine's paper feed reel, ensuring smooth paper flow. Activate the correction device and simultaneously wind the upper low-voltage coil 22 and the lower low-voltage coil 24. The upper low-voltage coil 22 and the lower low-voltage coil 24 must achieve high symmetry in the magnetic circuit and be tightly coupled to ensure uniform force on both coils, with copper foil of the same length and arranged vertically along the axial direction. After winding, evenly arrange the outer support strips 25 around the lower low-voltage coil 22 and the lower low-voltage coil 24, aligning the slots. Place the polyester tape into the slots and tighten it according to the specified tension. Bundle the low-voltage insulation cylinder 21 and the outer support strips 25, along with other low-voltage winding components, into a robust whole to improve resistance to sudden short circuits.

[0080] In this transformer, the low-voltage winding is wound with segmented copper foil 27, and an insulating ring 23 is added between the upper and lower segments to block the potential difference between the segments and form an oil flow channel between the upper and lower segments, thereby avoiding local overheating. In addition, the wide copper foil has a large current carrying capacity and can be wound on both upper and lower segments at the same time, which is convenient for operation and reduces the problem of large additional losses caused by incomplete transposition of multiple wires.

[0081] In some embodiments, the low-voltage winding has corner rings 37 at both ends of the coil, and the corner rings 37 are made of semiconductor paper and thermally modified paper.

[0082] Specifically, such as Figure 10 , Figure 11 As shown, the corner ring 37 is located at the end of the outermost copper foil 27, and the copper foil 27 has a chamfer. The corner ring 37 can be made of a sheet of semiconductor carbon black paper and two sheets of thermally modified paper. First, a sheet of semiconductor carbon black paper is wrapped around the beginning and end of the outer copper foil of the low-voltage winding coil, and then two sheets of thermally modified paper are wrapped around the semiconductor carbon black paper.

[0083] In some embodiments, the high-voltage winding includes a high-voltage insulating cylinder 34 and a high-voltage coil. The high-voltage coil is located outside the high-voltage insulating cylinder 34 and adopts a center-entry configuration. The high-voltage coil includes an upper high-voltage coil 4 and a lower high-voltage coil 5. The upper high-voltage coil 4 is located above the center-entry configuration, and the lower high-voltage coil 5 is located below the center-entry configuration. The upper high-voltage coil 4 and the lower high-voltage coil 5 induce voltages with the upper low-voltage coil 22 and the lower low-voltage coil 24, respectively.

[0084] In this transformer, the use of a centrally located high-voltage winding and a tangled coil structure increases longitudinal capacitance, reduces lightning strike voltages, and makes the potential distribution of the high-voltage winding relative to ground more symmetrical. This places the highest potential point in the middle rather than at the ends, thereby reducing the electric field strength at both ends of the high-voltage winding (near the pressure plate and yoke) and alleviating insulation stress in these weak areas. Furthermore, the high voltage of the high-voltage leads, by being led out in the middle, keeps them away from the upper and lower clamps, preventing partial discharge at sharp corners of the iron components and effectively reducing partial discharge in the product. In addition, the centrally located high-voltage winding, combined with the axial vertical arrangement of copper foil in the low-voltage winding, ensures that the ampere-turns distribution of the high-voltage and low-voltage windings is almost perfectly symmetrical and balanced in the axial direction. This significantly cancels and weakens the axial electrodynamic force generated during a short circuit, fundamentally improving the transformer's mechanical strength to withstand short-circuit impacts.

[0085] Furthermore, facing the low-voltage side, within a limited space and while ensuring insulation distance, the high- and low-voltage lead design in this transformer can avoid lead crossing (when leads cross or run parallel in close proximity, the superposition of magnetic fields will cause a local increase in magnetic flux density, leading to eddy current overheating of metal parts near the leads).

[0086] In some implementations, such as Figure 1 , Figure 2 As shown, an upper pressure plate 10 is provided above the high-voltage winding and the low-voltage winding, and a lower support plate 11 is provided at the bottom of the high-voltage winding and the low-voltage winding. The lower support plate 11 is sleeved on the core column of the transformer. Through the strong pressing of the lower support plate 11 and the upper pressure plate 10, the entire transformer body is formed into a solid whole, further resisting the remaining electrodynamic force, thereby further improving the resistance to sudden short circuits. In addition, the transformer core 1 is located on the upper pressure plate 10 and is clamped by a clamp. The clamp is provided with a transformer body pressure plate 8, and the transformer tank is provided with a tank positioning plate 9. The transformer body pressure plate 8 and the tank positioning plate 9 are connected by bolts to form a rigid positioning to ensure mechanical strength. The core lamination grounding is connected to the grounding bushing 62 by the core grounding lead 6, and the clamp is connected to the grounding bushing 62 by the clamp grounding lead 7, forming a double grounding system, which can avoid the formation of a loop and reduce stray losses.

[0087] In some implementations, such as Figure 12As shown, the first and last ends of the high-voltage coil are provided with small corner rings 36, which are made of E-grade DDP heat-resistant paper (i.e., Weidmann DPE fiber-reinforced diamond-patterned adhesive paper).

[0088] In some implementations, such as Figure 13 As shown, the high-voltage insulating cylinder is provided with a large angle ring 35 at both ends, and the large angle ring is made of Grade A sulfate pulp 351.

[0089] In some implementations, such as Figure 9 As shown, the multi-level insulation isolation assembly includes multiple high- and low-voltage oil channels 32 and multiple high- and low-voltage surrounding plates 33. The multiple high- and low-voltage oil channels 32 and the multiple high- and low-voltage surrounding plates 33 are alternately arranged, with the high-voltage insulating cylinder 34 adjacent to the high- and low-voltage surrounding plates 33. This divides the distance between the high-voltage winding and the low-voltage winding into the multiple oil gap intervals. In this embodiment, it can be optionally divided into seven oil gap intervals. Compared to the traditional five intervals, this design, combined with the natural ester insulating liquid described below, can improve the heat dissipation channels and form a multi-level electric field voltage division, optimizing the field strength and reducing the risk of insulation breakdown under high potential differences.

[0090] In some embodiments, the oil passage 32 between the high and low pressure systems is made of F-grade heat-resistant EPGC203 material (i.e., epoxy glass cloth laminate) support strips. The enclosure between the high and low pressure systems and the high-voltage insulation cylinder are both made of A-grade conventional extra-hard cardboard T4.

[0091] In some implementations, such as Figure 9 As shown, the composite insulation system also includes a low-voltage oil passage 31, which is located inside the low-voltage winding and is made of a support strip of E-class EPGC203 material 311 pasted on E-class DDP heat-resistant paper 312.

[0092] In this transformer, by using a combination of materials with different insulation and heat resistance grades and similar dielectric constants for the high-voltage and low-voltage windings, the heat resistance performance can be matched with the local electric stress, thus solving the problem of electric field distortion at the high-voltage input end to the copper foil end of the low-voltage winding.

[0093] In some implementations, the transformer uses a natural ester insulating liquid at ≥320°C as the coolant.

[0094] Specifically, natural ester insulating fluids possess characteristics such as high biodegradability and high ignition point, which comply with marine environmental regulations and reduce fire risks. High viscosity is one of the most significant physical properties of natural ester insulating fluids. By designing wider and denser vertical oil channels inside the low-voltage winding and increasing the thickness of the oil channels in the high-voltage winding (for example, from the traditional 3mm to 4.5mm), the resistance to high-viscosity oil flowing through narrow gaps can be significantly reduced.

[0095] In some implementations, such as Figures 17-18 As shown, the transformer's oil conservator 61 adopts a square capsule oil conservator, which improves space utilization and insulation fluid protection. Furthermore, the square capsule oil conservator has a cuboid bottom and a horizontal shape, ensuring the oil level remains level and the oil level gauge provides accurate readings. The square capsule oil conservator contains an acrylic elastic capsule. The acrylic elastomer material further enhances the capsule's oil resistance, enabling it to withstand long-term immersion in natural ester insulating fluid without swelling, hardening, or performance degradation, thus extending its service life and reliability. Simultaneously, the viscosity and other physical properties of the natural ester insulating fluid may affect the capsule's movement; the capsule design (such as crease flexibility) must be adapted accordingly. In this transformer, by combining the high flash point and biodegradable properties of the natural ester insulating fluid with the potential for reduced maintenance (such as fewer replacements due to wear) and longer lifespan offered by the square capsule, the overall safety and environmental performance of the transformer can be enhanced. The square capsule oil tank is equipped with a gas relay, bellows, maintenance-free dehumidifier 63, and stainless steel bellows shut-off valve on its side. The transformer oil tank is equipped with an oil drain valve and a ladder. The transformer oil tank is filled with the above-mentioned high flash point natural ester insulating liquid as a coolant. It has a high flash point, is easily degradable, and is safe and environmentally friendly.

[0096] In some implementations, both the transformer tank and the square capsule oil conservator are coated with a salt spray resistant and UV resistant coating. Through material upgrades and process optimization, the salt spray resistant and UV resistant design can significantly improve the transformer's weather resistance in harsh marine environments and extend the equipment's service life.

[0097] Specifically, the coating consists of multiple layers. After the metal surfaces of the transformer tank and the square capsule oil conservator are properly treated, a thermal spray zinc coating is first applied to obtain a zinc-sprayed coating with a thickness of 60~120μm, for example, 100μm, but not limited to this. Then, an epoxy quick-drying paint is applied to seal the coating, resulting in a sealing coating with a thickness of 10~60μm, for example, 30μm, but not limited to this. Then, a primer, intermediate coat, and topcoat are applied sequentially. The primer uses commercially available Sigm... The primer uses Sigmafast278 coating with a thickness of 40~100μm, for example, 60μm is optional, but not limited to this; the intermediate coat uses commercially available Sigmafast278 coating with a thickness of 120~240μm, for example, 180μm is optional; the topcoat uses commercially available Sigmafast550 coating with a thickness of 40~80μm, for example, 60μm is optional, but not limited to this; the total dry film thickness of the primer, intermediate coat and topcoat is >360μm.

[0098] In some implementations, such as Figures 1-3 As shown, the transformer also includes a vibration damping device 412, which is located between the high-voltage winding and the bottom plate of the transformer tank and between the low-voltage winding and the bottom plate of the transformer tank.

[0099] Specifically, such as Figures 14-16 As shown, the vibration damping device 12 includes an insulating cardboard 51, a first cardboard groove 52, a second cardboard groove 53, a vibration damping pad 54, and a cardboard 55. The second cardboard groove 53 is located on the insulating cardboard 51, the first cardboard groove 52 is located on the second cardboard groove 53, and the vibration damping pad 54 is located inside the first cardboard groove 52. The cardboard 55 is located at the bottom of the vibration damping pad 54, between the vibration damping pad 54 and the first cardboard groove 52. The insulating cardboard 51, the first cardboard groove 52, the second cardboard groove 53, and the vibration damping pad 54 are glued and positioned as a whole module, forming a three-stage vibration damping system. The second cardboard groove 53 has an opening, and the transformer tank bottom plate has positioning pins that match the opening. During installation, the entire module is fitted onto the positioning pins at once, which is simple and convenient, and ensures that the positions of all vibration damping devices are absolutely uniform and correct.

[0100] The shock absorption device in this embodiment is a rigid integral frame that firmly fixes the shock-absorbing pads inside the cardboard slot. No matter how much vibration or impact the transformer experiences, the shock absorption device moves as a whole. The weight of the transformer body can be evenly transferred to each shock-absorbing pad through the robust cardboard-cardboard slot structure, greatly reducing the risk of internal component displacement and avoiding the risk of premature failure of individual pads due to suspension or excessive force. It also prevents component loosening and insulation damage, thereby ensuring that the designed shock absorption performance is perfectly reproduced, guaranteeing long-term mechanical stability and operational reliability, simplifying the production and installation process, and improving efficiency.

[0101] The transformer for offshore photovoltaic systems in this embodiment has the following specific effects:

[0102] 1) By optimizing the high-voltage winding structure and the low-voltage winding structure, and setting up a composite insulation system, it has the characteristics of ultra-large voltage transformation ratio and dual-split low-voltage input. It can realize the direct conversion of 110kV voltage to an ultra-large span transformation ratio of 1.14~0.69kV. Moreover, this direct conversion structure can greatly reduce the number of equipment and system complexity, and also reduce the overall power generation efficiency due to energy loss in multiple links.

[0103] 2) The low-voltage winding has a double-split coil structure and adopts a dual-circuit design. When a photovoltaic subarray fails, it does not affect the entire power supply system, thus meeting the reliability requirements of photovoltaic power station power supply.

[0104] 3) By using natural ester insulating liquid as coolant, the biodegradability rate is ≥97%, the ignition point is ≥320℃, and the auto-ignition temperature is ≥400℃, which not only meets environmental protection requirements but also improves fire resistance and safety.

[0105] 4) By installing a square capsule oil tank on the top of the transformer oil tank, with an acrylic elastic capsule inside, the capsule completely isolates the natural ester insulating liquid from the air, preventing moisture and impurities from entering the square structure. Compared with the traditional round oil tank, the space utilization rate can be increased by up to 30%, which can be adapted to the compact installation space of offshore platforms.

[0106] 5) By applying a coating that resists salt spray and ultraviolet radiation, the weather resistance of the transformer in the harsh marine environment can be greatly improved, extending the service life of the equipment.

[0107] 6) By installing shock absorption devices, multiple vibration loads on the offshore platform can be effectively buffered, preventing component loosening and insulation wear, and ensuring the reliability of equipment operation.

[0108] 7) By optimizing the structure of high-voltage winding, low-voltage winding, core and clamps, for example, the high-voltage winding adopts a tangled continuous winding process, and the axial compressive strength of the winding is ≥50MPa, which can improve the ability to resist sudden short circuits, improve the transformer's fault resistance, and ensure the safe operation of the offshore photovoltaic system.

[0109] Example 2

[0110] This embodiment discloses a marine photovoltaic system, which includes the above-described marine photovoltaic transformer.

[0111] The photovoltaic system in this embodiment, including the above-mentioned offshore photovoltaic transformer, has ultra-high voltage ratio, dual-split low-voltage input, strong environmental adaptability, high safety and environmental protection performance, and strong short-circuit resistance, which can meet the key technical requirements for efficient, safe and environmentally friendly operation of offshore photovoltaic power plants.

[0112] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A transformer for offshore photovoltaics, characterized in that The high-voltage winding, the low-voltage winding and the composite insulation system are arranged on the bottom plate of the transformer oil tank. The high-voltage winding is arranged at one end of the bottom plate of the transformer oil tank and adopts a twisted coil structure. The low-voltage winding is arranged at the other end of the bottom plate of the transformer oil tank and adopts a double-split coil structure. The composite insulation system comprises a multi-stage insulation isolation assembly arranged between the high-voltage winding and the low-voltage winding, and a plurality of oil gap intervals are arranged in the multi-stage insulation isolation assembly to form a plurality of stepped insulation barriers.

2. The transformer for offshore photovoltaic applications according to claim 1, characterized in that, The low-voltage winding comprises a low-voltage insulation cylinder (21), a low-voltage upper coil (22), a middle insulation ring (23), a low-voltage lower coil (24) and an outer support bar (25). The low-voltage upper coil (22) is arranged at the upper part of the coil mold, the middle insulation ring (23) is arranged at the middle part of the coil mold, and the low-voltage lower coil (24) is arranged at the lower part of the coil mold. The top of the low-voltage upper coil (22) and the bottom of the low-voltage lower coil (24) are respectively provided with a copper head, the low-voltage upper coil (22) and the low-voltage lower coil (24) are both made of copper foil (27), and the length of the copper foil in the low-voltage upper coil (22) is the same as that in the low-voltage lower coil (24). The outer support bar (25) is arranged at the periphery of the low-voltage upper coil (22) and the periphery of the low-voltage lower coil (24), and the outer support bar (25) is provided with a notch, and a polyester belt is bound in the notch to bind the components in the low-voltage winding into one body.

3. The transformer for offshore photovoltaic applications according to claim 2, characterized in that, The thickness of the middle insulation ring (23) is greater than or equal to 40 mm.

4. The transformer for offshore photovoltaic applications according to claim 2, characterized in that, The coil first and last ends of the low-voltage winding are provided with angle rings (37) made of semiconductor paper and heat-modified paper.

5. The transformer for offshore photovoltaic applications according to claim 2, characterized in that, The high-voltage winding comprises a high-voltage insulation cylinder (34) and a high-voltage coil. The high-voltage coil is arranged outside the high-voltage insulation cylinder (34), the high-voltage coil adopts a middle wire entry, and the high-voltage coil comprises a high-voltage upper coil (4) and a high-voltage lower coil (5).

6. The transformer for offshore photovoltaic applications according to claim 5, characterized in that, The first and last ends of the high-voltage coil are provided with small angle rings (36) made of E-grade DDP heat-resistant paper. The first and last ends of the high-voltage insulation cylinder are provided with large angle rings (35) made of A-grade sulfate pulp.

7. The transformer for offshore photovoltaic applications according to claim 5, characterized in that, The multi-stage insulation isolation assembly comprises a plurality of high-low voltage oil channels (32) and a plurality of high-low voltage surrounding plates (33). The plurality of high-low voltage oil channels (32) and the plurality of high-low voltage surrounding plates (33) are arranged alternately, the high-voltage insulation cylinder (34) is adjacent to the high-low voltage surrounding plate (33), and the distance between the high-voltage winding and the low-voltage winding is divided into the plurality of oil gap intervals.

8. The transformer for offshore photovoltaic applications according to claim 7, characterized in that, The high-low voltage oil channel (32) is made of a support bar of F-grade temperature-resistant EPGC203 material; The high-low voltage surrounding plate (33) and the high-voltage insulation cylinder are both made of A-grade traditional hard paper board T4.

9. The transformer for offshore photovoltaic applications according to claim 8, characterized in that, The composite insulation system further comprises a low-voltage oil channel (31). The low-pressure oil passage (31) is arranged in the low-pressure winding and is made of E-grade DDP heat-resistant paper with F-grade temperature-resistant EPGC203 material.

10. The transformer for offshore photovoltaic applications according to any of claims 1 to 9, characterized in that, The transformer uses natural ester insulation liquid with ignition point greater than or equal to 320 DEG C as cooling liquid, and the oil conservator (61) of the transformer is a square capsule oil conservator with built-in acrylic ester elastic capsule.

11. The transformer for offshore photovoltaic applications according to claim 10, characterized in that, The transformer oil tank and the square capsule oil conservator are coated with salt-fog-resistant and ultraviolet-resistant coating.

12. The transformer for offshore photovoltaic applications according to claim 11, characterized in that, The transformer further comprises a damping device (12), The damping device (12) is arranged between the high-voltage winding and the bottom plate of the transformer oil tank and between the low-voltage winding and the bottom plate of the transformer oil tank.

13. The transformer for offshore photovoltaic applications according to claim 12, characterized in that, The damping device (12) has a three-stage damping structure and comprises an insulating paper board (51), a first paper groove (52), a second paper groove (53), a damping rubber pad (54) and a paper board (55). The second paper groove (53) is arranged on the insulating paper board (51), the first paper groove (52) is arranged on the second paper groove (53), and the damping rubber pad (54) is arranged in the first paper groove (52). The paper board (55) is arranged at the bottom of the damping rubber pad (54) and between the damping rubber pad (54) and the first paper groove (52).

14. An offshore photovoltaic system, characterized in that, The offshore photovoltaic transformer comprises the transformer according to any one of claims 1-13.

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