Cooling device, oil-immersed transformer and fishing-light complementary photovoltaic power generation system

Abstract

The embodiment of the invention discloses a cooling device, an oil-immersed transformer and a fishing-light complementary photovoltaic power generation system. The cooling device comprises a cooling box body, an oil well pump and an oil guide pipe. The cooling box body is used for accommodating a transformer body, transformer oil is filled in the cooling box body, the box wall of the cooling box body comprises an outer-layer box wall and an inner-layer box wall, a hollow cooling cavity is formed between the outer-layer box wall and the inner-layer box wall, an oil pumping port is formed in a box cover of the cooling box body, and an oil return port is formed in the bottom of the inner-layer box wall; the oil well pump is communicated with the oil pumping port and is used for pumping out the hot transformer oil in the cooling box body from the oil pumping port; the oil guide pipe is arranged in the hollow cooling cavity, the inlet end of the oil guide pipe communicates with the oil well pump, the outlet end of the oil guide pipe communicates with the oil return opening, and the oil guide pipe surrounds the inner-layer box wall. Cooling liquid is injected into the hollow cooling cavity and used for cooling the hot transformer oil flowing through the oil guide pipe. By means of the cooling device, the oil-immersed transformer can have a small occupied area.

Description

Technical Field

[0001] The embodiments of the present invention specifically relate to a cooling device, an oil-immersed transformer, and a solar-fishery complementary photovoltaic power generation system. Background Technology

[0002] Under the global trend of advocating a low-carbon economy and green energy, and with the background goal of "carbon peaking and carbon neutrality," the new energy power generation sector has achieved rapid and steady development. New energy (photovoltaic and wind power) power generation will gradually leap from auxiliary energy to primary energy. With the vigorous development of the new energy industry, the industrial layout of photovoltaic and wind power has gradually expanded, and the number of subdivided regions has increased year by year. Among them, photovoltaic power generation projects that combine fishery and solar power have seen relatively widespread product deployment in recent years.

[0003] A solar-aquaculture complementary photovoltaic power generation project refers to building photovoltaic power stations and other equipment in aquatic environments, where the water beneath the photovoltaic panels can be used for fish and shrimp farming. The majority of the supporting transformers are oil-immersed transformers, cooled by ONAN (oil-immersed self-cooling).

[0004] Oil-immersed transformers are typically equipped with multiple finned radiators, which can meet the required heat dissipation surface area of ​​the transformer. However, oil-immersed transformers with finned radiators as cooling devices occupy a large area.

[0005] In solar-aquaculture complementary photovoltaic power generation projects, the large area occupied by oil-immersed transformers will enlarge the pond embankment area, resulting in a reduction of the space for aquaculture operations, and even making it impossible to complete aquaculture operations normally. Summary of the Invention

[0006] The technical problem to be solved by the embodiments of the present invention is to address the above-mentioned deficiencies in the prior art by providing a cooling device, an oil-immersed transformer and a solar-fishery complementary photovoltaic power generation system, wherein the cooling device can effectively reduce the footprint of the oil-immersed transformer.

[0007] According to an embodiment of a first aspect of the present invention, a cooling device for an oil-immersed transformer is provided, comprising: a cooling tank, an oil pump, and an oil guide pipe.

[0008] The cooling chamber comprises an outer wall and an inner wall, with a hollow cooling cavity between them. The inner wall forms a cavity for housing the transformer body, which contains transformer oil. The cooling chamber cover has an oil extraction port, and the bottom of the inner wall has an oil return port. An oil pump is connected to the extraction port and is used to extract hot transformer oil from the cooling chamber. An oil guide pipe is arranged within the hollow cooling cavity, with its inlet connected to the oil pump and its outlet connected to the oil return port, and the pipe surrounds the inner wall. Coolant is injected into the hollow cooling cavity to cool the hot transformer oil flowing through the oil guide pipe.

[0009] The cooling device for the oil-immersed transformer in this embodiment of the invention utilizes a hollow cooling cavity between the outer and inner tank walls, filled with coolant. Hot transformer oil from the cavity is then drawn into an oil guide pipe within the hollow cooling cavity, where the coolant provides water cooling. The transformer oil flows through the oil guide pipe and return port, returning to the cooling tank to complete one hot oil cycle. This circulation continuously removes heat from the transformer body, effectively dissipating heat. Therefore, this device eliminates the need for external finned radiators, effectively reducing the transformer's footprint. Furthermore, the oil guide pipe surrounds the inner tank wall, maximizing longitudinal space and providing a larger heat exchange area within a limited footprint. This ensures more thorough heat exchange between the hot transformer oil and coolant, achieving a smaller footprint while maintaining transformer body performance.

[0010] In summary, the cooling device of this oil-immersed transformer can effectively reduce the floor space occupied by the oil-immersed transformer.

[0011] Optionally, the oil guide tube has a continuously bent, multi-layered spiral structure.

[0012] Optionally, the diameter of the oil guide pipe decreases layer by layer from top to bottom.

[0013] Optionally, the oil guide pipe includes a coil section and a return bend section. The coil section extends horizontally along the circumference of the hollow cooling cavity to form a spiral structure. There are multiple coil sections, which are spaced apart in the vertical direction. Adjacent coil sections are connected by return bend sections.

[0014] Optionally, each coil section is a section of equal diameter, with the diameter of the upper coil section being larger than that of the lower coil section. The diameter of the bend section gradually decreases from the top to the bottom, and the diameter of the upper end of the pipe corresponds to the diameter of the upper coil section, while the diameter of the lower end of the pipe corresponds to the diameter of the lower coil section.

[0015] Optionally, the bottom of the outer casing wall is provided with a water inlet, and the cover of the cooling box is provided with a water outlet, with the coolant flowing from the water inlet to the water outlet.

[0016] According to an embodiment of a second aspect of the present invention, an oil-immersed transformer is provided, including a transformer body and a cooling device for the oil-immersed transformer, wherein the transformer body is housed within a cooling box of the cooling device for the oil-immersed transformer.

[0017] Optionally, the oil-immersed transformer also includes an oil conservator connected to the cooling box, which is used to contain transformer oil overflowing from the cooling box.

[0018] According to an embodiment of a third aspect of the present invention, a photovoltaic power generation system for fishery-solar integration is provided, comprising a photovoltaic module and the aforementioned oil-immersed transformer; the photovoltaic module is electrically connected to the body of the oil-immersed transformer.

[0019] Optionally, the solar-fishery complementary photovoltaic power generation system also includes: a water pump and a water purification tank. The water purification tank is connected to the fishpond and is used to introduce water from the fishpond. A filter is installed at the inlet of the water purification tank to filter impurities in the fishpond water. The water pump is located between the cooling device of the oil-immersed transformer and the water purification tank. One end of the water pump is connected to the hollow cooling cavity of the cooling device of the oil-immersed transformer, and the other end is connected to the water purification tank. Attached Figure Description

[0020] Figure 1 This is a front view of an existing oil-immersed transformer (the dashed line represents a schematic diagram of the transformer substation section);

[0021] Figure 2 This is a top view of an existing oil-immersed transformer (the dashed line represents a schematic diagram of the transformer substation section);

[0022] Figure 3 This is a front view of the oil-immersed transformer in an embodiment of the present invention;

[0023] Figure 4 This is a top view of the oil-immersed transformer in an embodiment of the present invention;

[0024] Figure 5 This is a side view of an oil-immersed transformer according to an embodiment of the present invention;

[0025] Figure 6 This is a rear view of the oil-immersed transformer in an embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the oil guide pipe in an embodiment of the present invention.

[0027] In the diagram: 1. Oil-immersed transformer; 2. Transformer base; 3. High-voltage compartment; 4. Low-voltage compartment; 5. Plate radiator; 6. Oil conservator; 20. Oil pump; 30. Inner tank wall; 40. Outer tank wall; 50. Oil guide pipe; 51. Coil section; 52. Back bend section; 60. Water pump; 61. Purification tank; 62. Water inlet; 70. Water outlet; 71. Cooling tank; 80. Oil extraction port; 90. Oil return port. Detailed Implementation

[0028] The technical solutions of the invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without creative effort are within the scope of the invention.

[0029] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience and simplification of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0030] In the description of the present invention, the terms "first", "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

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

[0032] It should be noted that most of the box-type transformers (i.e., box-type substations) used in the fishery-photovoltaic complementary photovoltaic power generation project are Huabian products (i.e., combined box-type substations).

[0033] The conventional product structures include "pin" shape, "L" shape, etc. Most of the supporting transformers are oil-immersed transformers, and the cooling method is ONAN (oil-immersed self-cooling). The transformer is usually equipped with multiple groups of plate radiators to meet the required heat dissipation area of the transformer.

[0034] Specifically, please refer to Figure 1 、 2 As shown, the existing special oil-immersed transformer 1 for new energy box-type transformers is fixedly installed on the box-type transformer base 2 together with the high-voltage chamber 3 and the low-voltage chamber 4 to form a complete box-type transformer with an "L" structure. The oil conservator 6 installed on the oil-immersed transformer 1 is used to adjust the change in oil volume caused by thermal expansion and contraction during the operation of the transformer, and can meet the requirements for the safe and stable operation of the transformer. The plate radiator 5 installed on the oil-immersed transformer 1 is used to dissipate the heat generated by the no-load loss during the operation of the transformer and keep the temperature rise of the transformer within the range permitted by the national standard.

[0035] However, the plate-type radiator 5 is usually suspended on the tank wall of the oil-immersed transformer 1. The bumps during product transportation can easily cause the plates to break apart and become damaged, resulting in oil leakage accidents. In the case of fishery-solar complementary projects, this can cause large-scale water pollution, causing fish and shrimp to die and leading to high claims. The plate-type radiator 5 extends about 1 to 2 meters beyond the base 2 of the transformer, resulting in the large size of the existing new energy transformer box, which is difficult to meet the layout requirements of the new energy power station deployment site. In addition, the structure of multiple plate-type radiators will increase the amount of transformer oil and steel plates used, resulting in higher product costs.

[0036] Based on this, this invention proposes a cooling device for an oil-immersed transformer to solve the problems existing in the aforementioned plate-type heat sinks.

[0037] Example 1

[0038] Please see Figure 3 , Figure 4 and Figure 5 The present invention discloses a cooling device for an oil-immersed transformer, comprising: a cooling box, an oil pump 20, and an oil guide pipe 50.

[0039] The cooling chamber comprises an outer wall 40 and an inner wall 30, with a hollow cooling cavity between them. The inner wall forms a cavity for housing the transformer body, which is filled with transformer oil. The cooling chamber cover has an oil extraction port 80, and the bottom of the inner wall 30 has an oil return port 90. An oil pump 20 is connected to the oil extraction port 80 and is used to extract hot transformer oil from the cooling chamber through the port 80. An oil guide pipe 50 is arranged within the hollow cooling cavity, with its inlet end connected to the oil pump 20 and its outlet end connected to the oil return port 90. The oil guide pipe 50 surrounds the inner wall 30. Coolant is injected into the hollow cooling cavity to cool the hot transformer oil flowing through the oil guide pipe 50.

[0040] It should be noted that the cooling device for this oil-immersed transformer is applicable to oil-immersed transformers in any scenario, especially suitable for cooling oil-immersed transformers in solar-fishery complementary photovoltaic power generation projects.

[0041] In the cooling device of this oil-immersed transformer, by setting the oil extraction port 80 at the top and the oil return port 90 at the bottom, the high-temperature hot oil at the top can be quickly extracted by taking advantage of the characteristic of hot oil rising, thereby improving the cooling efficiency.

[0042] Furthermore, a hollow cooling cavity is provided between the outer casing wall 40 and the inner casing wall 30, and coolant is injected into the hollow cooling cavity. Then, hot transformer oil from the cooling box is drawn into the oil guide pipe 50 within the hollow cooling cavity, where the coolant and the hot transformer oil are water-cooled. The transformer oil flows through the oil guide pipe 50 and the return port 90, returning to the interior of the cooling box, completing one hot oil cycle. Compared to the plate radiator 5, which relies solely on airflow for heat dissipation, this cooling device uses water cooling to exchange heat and cool the hot transformer oil, resulting in higher heat dissipation efficiency.

[0043] As the hot transformer oil circulates, it continuously carries away heat from the transformer body, thus achieving heat dissipation. Therefore, this device eliminates the need for an external finned radiator 5 to cool the hot transformer oil, effectively reducing the transformer's footprint. Furthermore, the oil guide pipe 50 surrounds the inner tank wall 30. This structure fully utilizes the longitudinal space, providing a larger heat exchange area within a limited footprint. This ensures more thorough heat exchange between the hot transformer oil and coolant within the oil guide pipe 50, thereby achieving a smaller footprint while maintaining the transformer's performance.

[0044] Moreover, the oil guide pipe 50 surrounds the inner tank wall 30. This structure can make full use of the longitudinal space and provide a larger heat exchange area in a limited footprint, so that the heat exchange between the hot transformer oil and the coolant in the oil guide pipe 50 is more complete. Thus, a smaller footprint can be achieved while ensuring the cooling effect of the hot transformer oil.

[0045] In summary, the cooling device of this oil-immersed transformer enables the oil-immersed transformer to have a smaller footprint.

[0046] Compared to the plate-type radiator 5, the cooling device of this oil-immersed transformer 11 requires no external equipment, avoiding damage caused by transportation bumps and thus preventing oil leakage accidents. Furthermore, this cooling device has a small footprint, meeting the site deployment requirements of solar-aquaculture hybrid power generation projects. The elimination of heat sinks reduces the amount of transformer oil and steel plates used, lowering product costs.

[0047] Furthermore, in solar-aquaculture hybrid power generation scenarios, transformers are exposed to high humidity and high salt spray environments. Since plate-type radiators have a large exposed area, they are more prone to surface corrosion. Moreover, the complex surface structure of plate-type radiators makes comprehensive rust prevention treatment difficult.

[0048] The cooling device for the oil-immersed transformer in this embodiment eliminates the need for plate-type radiators, significantly reducing the exposed area of ​​steel components. Furthermore, the smooth outer surface of the cooling box allows for easy application of an anti-rust layer, such as acrylic paint, to the outer wall. By reducing the exposed area and applying a highly corrosion-resistant paint to the outer wall of the cooling box, the problem of large-scale corrosion in solar-aquaculture hybrid power generation scenarios can be effectively avoided.

[0049] Furthermore, the cooling device of this oil-immersed transformer also includes an oil temperature monitoring unit and a controller. The oil temperature monitoring unit is located at the inlet end of the oil guide pipe 50 and is used to monitor the temperature of the hot transformer oil flowing into the oil guide pipe 50. The controller is electrically connected to the oil temperature monitoring unit and the oil pump, and is used to receive the oil temperature monitoring signal sent by the oil temperature monitoring unit, and adjust the output power of the oil pump according to the oil temperature monitoring signal to regulate the flow rate of the transformer oil.

[0050] Specifically, the oil temperature monitoring unit can be a platinum resistance temperature sensor or a thermocouple, with its sensing end tightly fitted onto the outer surface of the inlet wall of the oil guide pipe. The controller can be a programmable logic controller (PLC), a microcontroller, or a dedicated control circuit.

[0051] The controller has a pre-set temperature-power mapping table. When the oil temperature signal indicates an increase in oil temperature, the controller increases the output power of the oil pump to increase the circulation rate of the transformer oil. When the oil temperature signal indicates a decrease in oil temperature, the controller decreases the output power of the oil pump to reduce the circulation rate of the transformer oil. The temperature-power mapping table can be determined by the operator based on actual needs.

[0052] For example, when the oil temperature signal indicates that the oil temperature is below a first preset threshold (e.g., 55°C), it indicates that the transformer is under light load or no load and requires less cooling capacity. The controller controls the oil pump to operate at a lower power (e.g., 70% of rated power) to maintain a lower base circulation rate of the transformer oil. This helps reduce the system's own energy consumption.

[0053] When the oil temperature signal indicates that the oil temperature is between the first preset threshold and the second preset threshold (e.g., 55℃~75℃), it indicates that the transformer load has increased. The controller then increases the power of the oil pump (e.g., operating at rated power), thereby increasing the circulation rate of the transformer oil, enhancing the cooling effect, and stabilizing the oil temperature within a reasonable range.

[0054] When the oil temperature signal indicates that the oil temperature is higher than the second preset threshold (e.g., 75°C), it indicates that the transformer is close to full load or overload and is generating a large amount of heat. The controller controls the oil pump to operate at maximum output power, so that the transformer oil circulates at maximum flow rate, maximizing the heat dissipation capacity of the cooling device and ensuring the safe operation of the transformer.

[0055] Please see Figure 6 and Figure 7 In this embodiment, the oil guide pipe 50 is a multi-layered spiral structure with continuous bends.

[0056] Specifically, the structure of the oil guide pipe 50 integrates a relatively long pipe length into a compact rectangular space, thus adapting to the flat shape of the hollow layer in the tank wall and maximizing space utilization. This makes the entire cooling device compact, helping to reduce the footprint of the oil-immersed transformer 11.

[0057] Within the limited internal space of the hollow layer in the tank wall, the multi-layer spiral design fully utilizes the longitudinal space of the hollow cooling cavity, significantly increasing the surface area of ​​the oil guide pipe 50 in contact with the coolant, thereby significantly improving heat exchange efficiency. Moreover, by making full use of the longitudinal space, the oil flow path can be extended without increasing the floor space, thus extending the residence time of the hot transformer oil in the cooling area.

[0058] Moreover, it is worth noting that repeated bends will disturb the oil flow, causing it to become turbulent, which can prevent the formation of a stagnant boundary layer near the pipe wall and enhance heat exchange efficiency.

[0059] Please see Figure 7 In this embodiment, the oil guide pipe 50 includes a coil section 51 and a return bend section 52. The coil section 51 extends horizontally along the circumference of the hollow cooling cavity to form a spiral structure. There are multiple coil sections 51, which are spaced apart in the vertical direction. Adjacent coil sections 51 are connected by the return bend section 52.

[0060] The center distance S between two adjacent coil sections 51 and the outer diameter D of the oil guide pipe 50 satisfy the following relationship: 2.5D≤S≤4.5D.

[0061] In some embodiments, the oil guide tube 50 may be designed with a constant diameter.

[0062] The following is a specific example of an equal-diameter oil guide pipe: From the front, the connection between the coiled section 51 and the return bend section 52 of the adjacent two layers of the oil guide pipe 50 is U-shaped, so the oil guide pipe 50 can also be called a U-shaped oil guide pipe.

[0063] The U-shaped oil guide tube, as an important oil circulation pipeline, is made of corrosion-resistant aluminum alloy and features rapid heat exchange. The oil guide tube is formed by continuously bending hollow tubes of equal diameter. The inner diameter of the tube is 30-60 mm, preferably 50 mm; the outer diameter of the U-shaped guide tube is 40-70 mm, preferably 56 mm. The tube wall thickness is 3-6 mm, preferably 3 mm. The standard for the tube wall thickness is that it must withstand 60 kPa of air pressure without any damage. Considering the bending strength of the oil guide tube, the center distance between adjacent layers is 200 mm. When the transformer is running, the power of the water pump is constant, and the water flow rate is constant at 3m / s. The power of the oil pump can be adjusted according to the oil temperature change, and the oil flow rate can be adjusted within the range of 1 to 6m / s. When the transformer load is large, the oil temperature rises, and the power of the oil pump increases accordingly to accelerate the oil flow rate and achieve rapid cooling. Conversely, when the transformer load is small, the oil temperature decreases, and the power of the oil pump decreases accordingly to slow down the oil flow rate, so that the transformer oil is always kept below the limit of 100℃.

[0064] In other embodiments, the diameter of the oil conduit 50 decreases progressively from top to bottom.

[0065] The upper oil guide pipe 50 has a larger diameter because its inlet is located at the top. The hot transformer oil reaches its highest temperature and lowest viscosity (i.e., better fluidity) when it first enters the oil guide pipe 50. With a fixed flow rate, increasing the pipe diameter reduces the oil flow velocity. This prolongs the residence time of the high-temperature oil at the top of the heat exchanger, ensuring sufficient time for it to transfer a large amount of heat to the cooling water.

[0066] The lower oil guide pipe 50 uses a smaller diameter because the oil viscosity increases after cooling, its fluidity decreases, and it is prone to sedimentation. Reducing the pipe diameter can increase the flow rate of transformer oil, prevent the deposition of impurities such as sludge, and avoid blockage and reduced heat exchange efficiency.

[0067] In other words, by gradually reducing the diameter of the oil guide pipe 50 from top to bottom, the uniformity of flow velocity throughout the pipe can be improved.

[0068] Furthermore, for any two adjacent coil sections 51, the center distance S and the outer diameter D of the upper coil section satisfy the following relationship: 2.5D ≤ S ≤ 4.5D. Preferably, the center distance S is 3.5 times the outer diameter D of the oil guide pipe. Taking the outer diameter of the upper coil section as an example of 50mm, the center distance is 175mm.

[0069] This spacing range represents the optimal range verified through fluid simulation and experiments. When the spacing S is less than 2.5D, the coolant flow resistance is too high, and dead zones are easily formed. When the spacing S is greater than 4.5D, the utilization rate of the tank wall space decreases, and the coolant flow velocity decreases, affecting heat exchange efficiency. By adopting a spacing within the above range, an optimal balance can be achieved between high heat exchange efficiency and low flow resistance energy consumption, and it works in conjunction with the variable pipe diameter design to ensure uniform heat exchange in each layer of coils.

[0070] Specifically, the shape of the coil section 51 is adapted to the shape of the hollow cooling cavity. In this embodiment, the coil section 51 is a rounded rectangle.

[0071] By arranging multiple coil sections 51 at vertical intervals, longitudinally superimposed flow channels can be achieved, resulting in a larger heat exchange area without increasing the floor space. Compared to plate radiators 5, this cooling device reduces the floor space while improving heat dissipation.

[0072] Optionally, each coil section 51 is a pipe section of equal diameter. The pipe diameter of the upper coil section 51 is larger than that of the lower coil section 51. The pipe diameter of the bend section 52 gradually decreases from the upper end to the lower end, and the pipe diameter at the upper end corresponds to the pipe diameter of the upper coil section 51, while the pipe diameter at the lower end corresponds to the pipe diameter of the lower coil section 51.

[0073] Specifically, the ratio of the diameter of the uppermost pipe to the inner diameter of the lowermost pipe can be between 1.2 and 1.5. For example, with a pipe diameter ratio of 1.2, the inner diameter of the uppermost coiled section 51 is 36mm, and the inner diameter of the lowermost coiled section 51 is 30mm. The pipe diameters of the intermediate coiled sections 51 can be selected according to the actual number of pipes. For example, when there are 5 intermediate coiled sections 51, the inner diameters of the coiled sections 51 from top to bottom can be 36, 35, 34, 33, 32, 31, and 30mm respectively.

[0074] Each coiled section 51 is a constant diameter section, while the bend section 52 is a variable diameter section. This design allows for easy fabrication and shaping of the oil guide pipe 50. Since the central axis of each coiled section 51 is on a horizontal plane, only one straight pipe needs to be bent to obtain one coiled section 51. By welding multiple coiled sections 51 together using bends with varying diameters, the overall fabrication of the oil guide pipe 50 can be completed.

[0075] The following is a specific example of a variable diameter oil guide pipe:

[0076] The U-shaped oil guide tube is made of corrosion-resistant aluminum alloy, which also features rapid heat exchange. The oil guide tube is formed by continuously bending hollow tubes of equal diameter. The inner diameter of the uppermost tube is 30-60 mm, preferably 54 mm; the outer diameter of the uppermost tube is 40-70 mm, preferably 60 mm. The inner diameter of the lowermost tube is 45 mm, and the outer diameter is 51 mm. The tube wall thickness is 3-6 mm, preferably 3 mm. The standard for the tube wall thickness is that it must withstand 60 kPa of air pressure without any damage. Considering the bending strength of the oil guide tube, the center distance between adjacent layers is 200 mm.

[0077] When the transformer is running, the power of the water pump is constant, and the water flow rate is constant at 3m / s. The power of the oil pump can be adjusted according to the oil temperature change, and the oil flow rate can be adjusted within the range of 1 to 6m / s. When the transformer load is large, the oil temperature rises, and the power of the oil pump increases accordingly to accelerate the oil flow rate and achieve rapid cooling. Conversely, when the transformer load is small, the oil temperature decreases, and the power of the oil pump decreases accordingly to slow down the oil flow rate, so that the transformer oil is always kept below the limit of 100℃.

[0078] Please see Figure 3 In this embodiment, the bottom of the outer box wall 40 is provided with a water inlet 62, and the box cover of the cooling box is provided with a water outlet 70. The coolant flows from the water inlet 62 to the water outlet 70.

[0079] The coolant flows from bottom to top, while the hot transformer oil flows from top to bottom. The two flows in opposite directions, creating convection, which facilitates rapid cooling of the hot oil.

[0080] The following is a description of the overall working process of the cooling device of this oil-immersed transformer 11:

[0081] First, the hot oil at the top of the cooling box is drawn to the inlet of the oil guide pipe 50 via the oil pump 20, which is connected to the oil extraction port 80 of the cooling box cover. After entering the oil guide pipe 50, the hot oil flows from top to bottom along its flow path. Simultaneously, coolant enters the hollow cooling chamber through the water inlet 62 located at the bottom of the outer box wall 40. Inside the hollow cooling chamber, the coolant flows from bottom to top, creating convection currents with the hot oil.

[0082] The hot oil first flows through the uppermost coil section 51, which has a larger pipe diameter. During this process, the high-temperature hot oil exchanges heat with the coolant outside the oil guide pipe 50, and the oil temperature begins to drop. Subsequently, the hot oil enters the lower coil section 51 through the variable-diameter bend pipe section 52. As the pipe diameter of the lower coil section 51 decreases layer by layer, the oil flow velocity increases with the decrease in pipe diameter, which avoids sludge deposition and allows for continuous deep heat exchange with the coolant. Finally, the low-temperature transformer oil, after being cooled by multiple coil sections, flows through the outlet end of the oil guide pipe 50 into the return port 90 at the bottom of the inner tank wall 30, and flows back into the cooling tank, completing one hot oil cycle.

[0083] In summary, the cooling device of this oil-immersed transformer 11 enables the oil-immersed transformer 11 to have a smaller footprint while improving the cooling effect on the transformer body.

[0084] Example 2

[0085] Please see Figure 3 , Figure 4 and Figure 5 The present invention also discloses an oil-immersed transformer 11, comprising: a transformer body and a cooling device for the oil-immersed transformer 11 in Embodiment 1. The transformer body is housed within the cooling box of the cooling device for the oil-immersed transformer 11.

[0086] The oil-immersed transformer 11 in this embodiment can be used in any transformer scenario, and is especially suitable for solar-fishery complementary photovoltaic power generation projects.

[0087] It should be noted that while conventional transformer layout schemes can meet the needs of the new energy industry, they also have the following drawbacks:

[0088] First, due to the product structure, the radiator extends 21-2m beyond the transformer base, increasing the product's footprint and making it less suitable for areas with limited land acquisition.

[0089] Secondly, the radiator is fixed by a suspension structure from the box wall. The product is prone to damage during transportation due to bumps, which can lead to oil leakage accidents. Furthermore, after the transformer is installed on the platform, it is not easy to place an oil collection trough on the bottom of the radiator that extends beyond the base. If an oil leakage accident occurs, the transformer oil will pollute the nearby waters and cause environmental damage.

[0090] Third, the multi-plate structure increases the amount of transformer oil and steel plates used, resulting in higher product costs and weaker market competitiveness.

[0091] Fourth, in the scenario of solar-fishery complementary photovoltaic power generation, the transformer is in a high humidity and high salt spray environment for a long time, and the exposed sheet corrosion is severe, making on-site repair extremely difficult.

[0092] Based on this, the oil-immersed transformer 11 in this embodiment of the invention adopts the cooling device of the oil-immersed transformer 11 in embodiment 1, which can solve the above problems.

[0093] In this embodiment, the oil-immersed transformer 11 is part of the solar-fishery complementary photovoltaic power generation transformer box-type substation. It is installed together with the high-voltage compartment 3 and the low-voltage compartment 4 on the transformer box-type substation base 2, forming a complete "L"-shaped transformer box-type substation. The transformer is an oil-immersed transformer 11, exposed on the outside of the transformer box-type substation casing, equipped with an oil conservator 6, but without a plate-type heat sink 5.

[0094] An oil pump 20 is installed on the transformer box cover (i.e., the cover of the cooling box). One end of the oil pump 20 is connected to the oil inlet 80 arranged on the box cover, and the other end is connected to the "U"-shaped oil guide pipe 50. That is, from the front, the connection between the coil section 51 and the return bend section 52 of the adjacent two layers of the oil guide pipe 50 is "U"-shaped.

[0095] A water pump 60 is installed at the bottom of the transformer tank. One end of the water pump 60 is connected to the purification pool 61 of the solar-fishery complementary photovoltaic power station, and the other end is connected to the water inlet 62 at the bottom of the tank wall.

[0096] The transformer's four-sided cooling box walls are double-layered hollow structures. A U-shaped oil guide pipe 50 is arranged in the hollow space between the inner and outer box walls 40. The inner box wall 30 is a welded steel plate structure with an oil inlet at the bottom (i.e., the aforementioned oil return port 90; all subsequent oil inlets refer to the aforementioned oil return port 90, which will not be elaborated upon further). One end of the U-shaped oil guide pipe 50 is connected to this oil inlet, allowing the cooled transformer oil to flow back into the cooling box. The other end of the U-shaped oil guide pipe 50 is connected to the oil pump 20. The outer box wall 40 is a hinged panel structure. An outlet 70 is provided at the upper end of the outer box wall 40 for connecting to the cooling pool 71, and an inlet 62 is provided at the lower end of the outer box wall 40 for connecting to the water pump 60. The hinged panel joints are sealed with rubber gaskets.

[0097] In addition, the transformer circulates oil via an oil pump 20. Hot oil is drawn from the tank cover, cooled from top to bottom through a U-shaped oil guide pipe 50, and then flows back into the cooling tank from the bottom. The transformer circulates water via a water pump 60. Cold water is drawn from a purification tank 61 and flows from the bottom inlet 62 into the hollow part of the double-layer tank wall (i.e., the hollow cooling chamber mentioned above). The water cools the hot oil in the U-shaped oil guide pipe 50 from bottom to top, and then flows back to the cooling tank 71 from the top outlet 70. The cold water and hot oil flow in opposite directions, forming convection, which facilitates rapid cooling of the hot oil.

[0098] In this embodiment, the oil-immersed transformer 11 also includes an oil conservator 6, which is connected to the cooling tank. The oil conservator 6 is used to contain transformer oil overflowing from the cooling tank. The oil conservator 6 is used to regulate the changes in oil volume caused by thermal expansion and contraction during product operation. By retaining the oil conservator 6, the long-term safe and stable operation of the transformer can be ensured.

[0099] In summary, the main difference between the oil-immersed transformer 11 in this embodiment and existing new energy supporting transformers lies in the following: the single-layer tank walls on all four sides of the transformer are replaced with double-layer tank walls. An outer tank wall 40 is added to the inner tank wall 30, forming a hollow space between the inner and outer tank walls 40. A U-shaped oil guide pipe 50 is arranged in the hollow space, and the plate-type radiator 5 is eliminated. The transformer's heat dissipation method is changed from natural cooling to water cooling. During operation, the output power of the oil pump can be controlled by monitoring changes in oil temperature, thereby adjusting the flow rate of the transformer oil and enabling rapid adjustment of the oil temperature according to the transformer load.

[0100] The oil circulation circuit of this transformer is described as follows:

[0101] Because the hot oil is concentrated at the top of the cooling tank, an oil extraction port 80 is arranged in the middle of the tank cover to achieve rapid cooling of the hot oil. The port is connected to an oil pump 20 arranged on the tank cover via a steel pipe. The oil pump 20 continuously extracts the hot oil from the cooling tank and enters the U-shaped oil guide pipe 50 connected to the oil pump 20. Considering corrosion resistance and heat conduction rate, the U-shaped oil guide pipe 50 is made of aluminum alloy. The hot oil flows from top to bottom in the U-shaped oil guide pipe 50, and the heat is exchanged with the cold water on the outside of the oil guide pipe 50 to achieve rapid cooling of the transformer oil. After cooling, the transformer oil flows back into the cooling tank through the oil inlet arranged on the inner tank wall 30, forming a complete oil circulation loop.

[0102] The water circulation loop of this transformer is described below:

[0103] Leveraging the resource advantages of the solar-fishery complementary project, water is drawn from nearby transformer substations and purified in purification pool 61 before being used as cooling water. Purification pool 61 is connected to water pump 60 fixed on the bottom of the transformer box via a steel pipe. After being pressurized by water pump 60, the cooling water is pumped into inlet 62 located at the bottom of the outer box wall 40 of the transformer, allowing the cooling water to enter the hollow area between the inner box wall 30 and the outer box wall 40. The cooling water cools the hot oil in the U-shaped oil guide pipe 50 from bottom to top. Then, the hot water flows out from outlet 70 located at the top of the outer box wall 40 and flows into cooling pool 71 through steel pipe. After being cooled, the hot water flows back into purification pool 61 for recycling.

[0104] In addition, to ensure the long-term safe and stable operation of the transformer, oil conservator 6 is retained to regulate the changes in oil volume caused by thermal expansion and contraction during product operation.

[0105] This oil-immersed transformer 11 is particularly suitable for solar-aquaculture integrated projects. By fully utilizing the resource advantages of these projects, it draws water from nearby locations around the transformer and uses water cooling instead of the natural cooling method of conventional transformers, significantly reducing the product's size. Furthermore, this oil-immersed transformer 11 saves on transformer oil and steel plate usage, conserving floor space and significantly reducing product costs, thus enhancing its market competitiveness. The absence of suspended components significantly improves transportation safety, reduces the risk of oil leakage, and contributes to improved environmental performance. Simultaneously, this oil-immersed transformer drastically reduces the exposed area of ​​steel components and eliminates easily corroded areas such as sharp corners and thin plates. Multiple coats of high-corrosion-resistant paint on the tank walls are sufficient to solve the corrosion problem of large-area corrosion in solar-aquaculture integrated projects using conventional solutions.

[0106] This oil-immersed transformer is part of a new energy prefabricated substation, suitable for photovoltaic power generation substations that integrate fisheries and solar power. This oil-immersed transformer, along with the high-voltage and low-voltage compartments, is installed on the substation base, forming a complete "L"-shaped substation. The oil-immersed transformer is exposed on the outside of the substation casing and is equipped with an oil conservator, eliminating the need for plate-type radiators. The transformer circulates oil through an oil pump located on the tank cover. The pump is connected to an oil inlet on the tank cover and a "U"-shaped oil guide pipe. Hot oil is drawn from the tank cover, cooled from top to bottom through the "U"-shaped oil guide pipe, and then flows back into the cooling tank from the bottom. The transformer also circulates water through a water pump located at the bottom of the tank. This pump is connected to a purification tank and a water inlet at the bottom of the cooling tank. Cold water flows from the hollow space between the double-layered tank walls to cool the hot oil in the "U"-shaped oil guide pipe. The water flow is from bottom to top, opposite to the oil flow, creating convection for rapid cooling of the hot oil.

[0107] This transformer can fully utilize the resource advantages of the fishery-solar complementary project, significantly reduce the amount of transformer oil used, and reduce the risk of oil leakage by eliminating the use of plate radiators, saving the overall footprint of the unit and thus achieving high economic benefits.

[0108] Example 3

[0109] The present invention also discloses a solar-fishery complementary photovoltaic power generation system, including photovoltaic modules and the oil-immersed transformer 11 in Embodiment 2.

[0110] The photovoltaic module is electrically connected to the body of the oil-immersed transformer 11 in Example 2.

[0111] Furthermore, the solar-fishery complementary photovoltaic power generation system also includes: a water pump 60 and a water purification tank. The water purification tank is connected to the fishpond and is used to introduce water from the fishpond. A filter is installed at the inlet of the water purification tank to filter impurities in the fishpond water. The water pump 60 is located between the cooling device of the oil-immersed transformer 11 and the water purification tank. One end of the water pump 60 is connected to the hollow cooling cavity of the cooling device of the oil-immersed transformer 11, and the other end is connected to the water purification tank.

[0112] This solar-fishery complementary photovoltaic power generation system, by using an oil-immersed transformer 11 with a small footprint, can avoid the space for aquaculture operations being compressed. Furthermore, the oil-immersed transformer 11 in Example 2 can also avoid the risk of large-scale oil leakage.

[0113] 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 cooling device for an oil-immersed transformer, characterized in that, include: Cooling box, oil pump (20) and oil guide pipe (50), The cooling box includes an outer box wall (40) and an inner box wall (30). A hollow cooling cavity is provided between the outer box wall (40) and the inner box wall (30). The inner box wall (30) forms a cavity for accommodating the transformer body. The cavity is filled with transformer oil. The cooling box is provided with an oil extraction port (80) on the box cover and an oil return port (90) at the bottom of the inner box wall (30); The oil pump (20) is connected to the oil extraction port (80) and is used to extract hot transformer oil from the cooling box from the oil extraction port (80); The oil guide pipe (50) is arranged in the hollow cooling cavity. The inlet end of the oil guide pipe (50) is connected to the oil pump (20), and the outlet end is connected to the oil return port (90). The oil guide pipe (50) surrounds the inner box wall (30). The hollow cooling cavity is filled with coolant, which is used to cool the hot transformer oil flowing through the oil guide pipe (50).

2. The cooling device for an oil-immersed transformer according to claim 1, characterized in that, The oil guide pipe (50) has a continuously bent multi-layer spiral structure.

3. The cooling device for an oil-immersed transformer according to claim 2, characterized in that, The diameter of the oil guide pipe (50) decreases layer by layer from top to bottom.

4. The cooling device for an oil-immersed transformer according to claim 3, characterized in that, The oil guide pipe (50) includes a coil section (51) and a return bend section (52). The coil section (51) extends horizontally along the circumference of the hollow cooling cavity to form a spiral structure. The number of coil sections (51) is multiple, and the multiple coil sections (51) are arranged at intervals in the vertical direction. Adjacent coil sections (51) are connected by a bend section (52).

5. The cooling device for an oil-immersed transformer according to claim 4, characterized in that, Each coil section (51) consists of pipe sections of equal diameter, with the pipe diameter of the upper coil section (51) being larger than that of the lower coil section (51). The diameter of the bend section (52) gradually decreases from the top to the bottom, and the diameter of the upper pipe opening corresponds to the diameter of the upper coil section (51), while the diameter of the lower pipe opening corresponds to the diameter of the lower coil section (51).

6. The cooling device for an oil-immersed transformer according to claim 5, characterized in that, The bottom of the outer box wall (40) is provided with a water inlet (62), and the box cover of the cooling box is provided with a water outlet (70). The coolant flows from the water inlet (62) to the water outlet (70).

7. An oil-immersed transformer, characterized in that, The transformer includes a body and a cooling device for an oil-immersed transformer as described in any one of claims 1 to 6, wherein the body is housed within a cooling box of the cooling device for the oil-immersed transformer.

8. The oil-immersed transformer according to claim 7, characterized in that, The oil-immersed transformer also includes an oil conservator (6), which is connected to the cooling box and is used to contain transformer oil overflowing from the cooling box.

9. A photovoltaic power generation system that integrates fisheries and solar power, characterized in that, Includes photovoltaic modules and the oil-immersed transformer as described in claim 7 or 8; The photovoltaic module is electrically connected to the body of the oil-immersed transformer.

10. The solar-fishery complementary photovoltaic power generation system according to claim 9, characterized in that, The solar-fishery complementary photovoltaic power generation system also includes: a water pump (60) and a water purification tank. The water purification tank is connected to the fishpond and is used to introduce water from the fishpond. A filter is installed at the inlet of the water purification tank to filter impurities in the fishpond water. The water pump (60) is located between the cooling device of the oil-immersed transformer and the clean water tank. One end of the water pump (60) is connected to the hollow cooling cavity of the cooling device of the oil-immersed transformer, and the other end is connected to the clean water tank.

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