Coupled heat dissipation system and method

Abstract

The application discloses a coupling heat dissipation system and method, which comprises the following steps: coupling a first cooling medium loop of an oil-immersed transformer and a second cooling medium loop of a power conversion device through an intermediate heat exchange unit, and realizing non-contact heat transfer between the first cooling medium and the second cooling medium, so that the situation that traditional independent heat dissipation systems are isolated from each other is broken. The waste heat generated by the power conversion device can preheat the oil-immersed transformer through the intermediate heat exchange unit, so that the heating energy consumption of the transformer in a low-temperature environment is reduced; and the heat generated by the oil-immersed transformer can be efficiently discharged through the cooling loop of the power conversion device, so that the heat is prevented from being lost in disorder. Therefore, the bidirectional collaborative utilization of heat is realized, and the comprehensive energy efficiency of the system is significantly improved.

Description

Technical Field

[0001] This application relates to the technical field of key equipment in large-scale electrochemical energy storage power stations, and in particular to a coupled heat dissipation system and method. Background Technology

[0002] In a converter-boost integrated power supply unit, the power conversion equipment and the oil-immersed transformer typically have their own independent cooling systems. Specifically, the oil-immersed transformer mainly relies on natural oil circulation, plate radiators, or forced air cooling for heat dissipation. The power conversion equipment absorbs the heat generated by the power devices through liquid cooling plates and then dissipates the heat to the external environment via a fan-liquid heat exchanger. These independent cooling systems are fragmented and cannot achieve coordinated heat utilization, resulting in energy waste.

[0003] Furthermore, the air-liquid heat exchangers of power conversion equipment are usually located at the top or inside their cabinets, significantly increasing the overall size of the cabinet and hindering the miniaturization and standardization of the equipment. In addition, the hot air exhausted from the air-liquid heat exchangers can easily flow back to the air inlet of the electronic cavity of the power conversion equipment, forming a thermal short circuit, which seriously affects the heat dissipation efficiency and operational reliability of the equipment.

[0004] In summary, the heat dissipation performance of existing converter-boost integrated power supply units is insufficient, and an innovative heat dissipation solution is urgently needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] This application proposes a coupled heat dissipation system and method to optimize heat dissipation energy consumption.

[0006] To achieve the above objectives, this application discloses the following technical solutions: This application provides a heat dissipation system for coupling an oil-immersed transformer with a power conversion device, including: The oil-immersed transformer is connected to a first cooling circuit, which is equipped with a first pump, and a first cooling medium circulates within the first cooling circuit. The power conversion device is connected to a second cooling circuit, which is equipped with a second pump, and a second cooling medium circulates within the second cooling circuit. An intermediate heat exchange unit has a first heat exchange channel and a second heat exchange channel. A first cooling circuit is connected to the first heat exchange channel, and a second cooling circuit is connected to the second heat exchange channel. Along the flow direction of the second cooling medium, the second heat exchange channel is located upstream of the external heat dissipation equipment.

[0007] In some embodiments, external heat dissipation devices are located on the top, side, or adjacent to the oil-immersed transformer.

[0008] In some embodiments, each power conversion device is provided with a branch valve, which is configured to regulate the flow rate of the second cooling medium entering the corresponding power conversion device; The first cooling circuit is connected in series with the first valve; The second cooling circuit has a second valve connected in series.

[0009] In some embodiments, a controller is also included, which is communicatively connected to a first pump in a first cooling circuit, a second pump in a second cooling circuit, an external heat dissipation device, a first valve, and / or a second valve, and is configured to control the operating status of the first pump, the second pump, the external heat dissipation device, the first valve, and / or the second valve based on the temperature of the first cooling medium, the temperature of the second cooling medium, and / or the ambient temperature.

[0010] In some embodiments, the first cooling circuit is also connected to a spray structure, which is located above or around the oil-immersed transformer, with the spray direction of the spray structure facing the oil-immersed transformer.

[0011] Secondly, embodiments of this application provide a coupling heat dissipation method applied to the aforementioned coupling heat dissipation system, comprising: When the temperature of the first cooling medium is higher than the temperature of the second cooling medium, the first pump drives the first cooling medium to circulate in the first cooling circuit of the oil-immersed transformer to absorb the heat generated by the oil-immersed transformer; the second pump drives the second cooling medium to circulate in the second cooling circuit of the power conversion device to absorb the heat generated by the power conversion device. The second cooling medium, after absorbing the heat from the power conversion device, is guided to the second heat exchange channel of the intermediate heat exchange unit; The second cooling medium, after being heated by the intermediate heat exchange unit, is guided to an external heat dissipation device, where ambient air cools the second cooling medium.

[0012] In some embodiments, the method further includes: To obtain the temperature of the first cooling medium of the oil-immersed transformer and / or the temperature of the second cooling medium of the power conversion equipment; When the temperature of the first cooling medium is not lower than the first set temperature and / or the temperature of the second cooling medium is not lower than the second set temperature, the first pump, the second pump, and the external heat dissipation equipment are started; wherein, the first set temperature is greater than the second set temperature; The first pump drives the first cooling medium to flow through the first heat exchange channel of the intermediate heat exchange unit; The second pump drives the second cooling medium to flow through the liquid cooling channel of the power conversion equipment, the second heat exchange channel of the intermediate heat exchange unit, and the external heat dissipation equipment. External heat dissipation equipment drives ambient air to flow through it.

[0013] In some embodiments, the method further includes: When the temperature of the first cooling medium of the oil-immersed transformer continues to rise and the external heat dissipation equipment reaches the preset output state, the flow rate of the first pump and / or the second pump is gradually increased.

[0014] In some embodiments, the method further includes: Obtain the temperature of the first cooling medium in the oil-immersed transformer; When the temperature of the first cooling medium is not higher than the third set temperature and not lower than the fourth set temperature, the power conversion device, the second pump and the first pump are started, and the external heat dissipation device is turned off or the speed of the external heat dissipation device is reduced. The third set temperature is lower than the first set temperature and higher than the fourth set temperature.

[0015] In some embodiments, the method further includes: When the oil-immersed transformer is shut down or the temperature of the first cooling medium of the oil-immersed transformer is lower than the fourth set temperature, the first pump is shut down. Start the second pump and external cooling equipment.

[0016] In some embodiments, the method further includes at least one of the following: When multiple power conversion devices are connected in parallel to the second cooling circuit, the flow rate of the second cooling medium in the corresponding branch of each power conversion device is adjusted according to the operating load of each power conversion device, the temperature of the second cooling medium, and / or the heat dissipation requirements. When an oil-immersed transformer is detected to be in an abnormal temperature rise, thermal runaway or fire risk state, a first cooling medium or a flame-retardant cooling medium is sprayed onto the surface of the oil-immersed transformer through a spray structure to cool down and / or isolate oxygen. The first cooling medium is a non-flammable cooling medium. After the second cooling medium absorbs heat from the first cooling medium through the intermediate heat exchange unit, the second cooling medium enters the external heat dissipation equipment.

[0017] As can be seen from the above technical solutions, this application provides a coupled heat dissipation system and method. It is well known in the art that the winding and oil temperatures of an oil-immersed transformer are typically significantly higher than the operating temperature of the power conversion equipment during normal operation, resulting in a natural temperature difference between the two. Based on this physical characteristic, this application couples the first cooling circuit of the oil-immersed transformer with the second cooling circuit of the power conversion equipment through an intermediate heat exchange unit, enabling non-contact heat exchange between the high-temperature first cooling medium and the relatively low-temperature second cooling medium within the intermediate heat exchange unit.

[0018] Unlike conventional heat dissipation designs that strive for "independent circuits to avoid mutual interference," this application breaks with technical bias and actively introduces the high-temperature waste heat of the oil-immersed transformer into the second cooling circuit of the power conversion equipment through the first cooling circuit. This not only preheats the oil-immersed transformer but also utilizes the high-temperature heat energy of the oil-immersed transformer to "reheat" the second cooling medium that has absorbed heat from the power conversion equipment. This further increases the temperature of the cooling medium entering the external heat dissipation equipment, increases the temperature difference between it and the ambient air, and thus significantly improves the heat dissipation efficiency of the external heat dissipation equipment.

[0019] Therefore, this application enhances the heat dissipation capacity of the power conversion equipment by utilizing the waste heat originally discarded by the oil-immersed transformer without increasing the specifications of external heat dissipation equipment. This achieves a synergistic heat dissipation effect of "heat assisting cooling," effectively solving the technical challenge of the prominent heat dissipation bottleneck of the converter-boost integrated machine in high power density scenarios. At the same time, this coupled heat dissipation system does not require additional large plate heat sinks or forced air cooling devices for the oil-immersed transformer, nor does it require increasing the heat dissipation area of ​​the power conversion equipment separately. This helps to simplify the overall layout and reduce the size of the machine, providing strong support for the miniaturization and high-efficiency design of the equipment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort, and this application can be applied to other similar scenarios based on the provided drawings. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0021] Figure 1 and Figure 2 A perspective view of the first coupling heat dissipation system provided in the embodiments of this application; Figure 3 This is a schematic diagram of a first coupling heat dissipation system provided in an embodiment of this application; Figure 4 This is a schematic diagram of a second type of coupled heat dissipation system provided in an embodiment of this application; Figure 5 This is a schematic diagram of a third type of coupled heat dissipation system provided in an embodiment of this application; Figure 6 This is a schematic diagram of the first coupling heat dissipation method provided in the embodiments of this application; Figure 7 This is a schematic diagram of the fourth coupling heat dissipation system provided in the embodiments of this application; Figure 8This is a schematic diagram of the fifth coupling heat dissipation system provided in the embodiments of this application; Figure 9 This is a schematic diagram of the second coupling heat dissipation method provided in the embodiments of this application; The annotations in the attached figures are explained as follows: 1. Oil-immersed transformer; 2. Power conversion equipment; 3. Intermediate heat exchange unit; 31. First heat exchange channel; 32. Second heat exchange channel; 4. First cooling circuit; 5. Second cooling circuit; 41. First pump; 42. First valve; 6. External heat dissipation equipment; 51. Second pump; 52. Second valve; 61. Heat exchange core; 62. Fan; 2a. First power conversion equipment; 2b. Second power conversion equipment; 2c. Third power conversion equipment; 53. Branch valve; 7. Controller; 8. Spray structure; 81. Spray pipe; 82. Spray head; 83. Spray valve; 9. Filtration device; 91. First filter; 92. Second filter. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] It should be noted that the terminology used in the following embodiments is only for describing specific embodiments and is not intended to limit this application. As used in this specification and claims, the singular forms such as "a," "the," and "the" are also intended to include the plural forms, unless the context explicitly defines otherwise. It should also be understood that the terms "comprising," "including," "having," and variations thereof, as used in this application, are intended to cover non-exclusive inclusion. For example, a system, apparatus, or device that comprises a series of components is not necessarily limited to the listed components, but may also include other components not explicitly listed, or components inherent to the system, apparatus, or device.

[0024] In the description of the embodiments of this application, terms such as "first," "second," "third," and "fourth" are only used to distinguish different objects, different components, or different setting conditions, and do not indicate their importance, quantity, spatial location, or order, nor should they be construed as limiting the scope of protection of this application. For example, "first cooling medium" and "second cooling medium" are only used to distinguish the cooling medium flowing through the oil-immersed transformer side and the cooling medium flowing through the power conversion equipment side, and do not indicate their priority in terms of function, temperature, or flow rate.

[0025] The terms "connection," "connection," "setting," "arrangement," and "thermal coupling" used in the embodiments of this application can be understood as direct connection, direct connection, direct setting, direct arrangement, or direct thermal coupling, depending on the specific structure. They can also be understood as indirect connection, indirect connection, indirect setting, indirect arrangement, or indirect thermal coupling through intermediate components, unless the context explicitly defines otherwise. The "cooling circuit" mentioned herein refers to the circulation of cooling medium within a relatively closed pipe or channel. The cooling medium typically does not directly contact the outside air, thereby reducing the risk of medium contamination, evaporation, and leakage, and improving the reliability of system operation.

[0026] For ease of explanation, this application describes a typical application scenario using an integrated converter-boost unit. This integrated converter-boost unit may include an oil-immersed transformer and power conversion equipment. The oil-immersed transformer can be used to boost or buck the voltage, and the power conversion equipment may include a converter, inverter, rectifier, DC / DC converter, PCS power module, power cabinet, or other power electronic equipment that includes power devices and generates heat. In practical applications, the oil-immersed transformer and power conversion equipment can be installed in the same enclosure, the same skid-mounted platform, the same cabin, the same machine room, or adjacent areas, or they can be installed in adjacent but independent installation spaces. This application does not limit this.

[0027] In existing integrated converter-boost converters, the oil-immersed transformer and the power conversion equipment typically employ independent cooling solutions. The oil-immersed transformer relies on natural oil circulation, plate heat sinks, air-cooled heat sinks, or forced oil circulation air-cooling devices for heat dissipation; the power conversion equipment usually absorbs heat from the power devices through liquid cooling plates, and then exhausts the heat to the outside air through external cooling devices 6 located on the top or inside of the power cabinet. These two types of cooling systems are isolated from each other, making it difficult to achieve coordinated heat distribution and increasing the overall size of the unit, the number of fans, and thermal management energy consumption. Especially when the external cooling devices 6 of the power conversion equipment are located on the top or inside the cabinet, the hot air exhausted by the external cooling devices 6 may flow back to the air inlet of the electronic cavity of the power conversion equipment, forming a thermal short circuit, causing the inlet temperature of the electronic components to rise, and thus affecting the operational reliability of the power conversion equipment.

[0028] In conventional understanding, the power conversion equipment and oil-immersed transformer in a converter-boost integrated unit are usually equipped with their own independent cooling systems. Designers generally tend to avoid mixing or coupling cooling media of different temperature levels to prevent thermal interference from the high-temperature circuit to the low-temperature circuit, thus worsening the heat dissipation conditions of the low-temperature circuit. However, the applicant in this case discovered through research that the oil temperature of the oil-immersed transformer during normal operation is much higher than the allowable operating temperature of the power module of the power conversion equipment, with a significant temperature difference between the two. Based on this, this application unconventionally couples the cooling circuit of the oil-immersed transformer with the cooling circuit of the power conversion equipment through an intermediate heat exchange unit. Instead of using the cooling capacity of the low-temperature power conversion equipment's cooling circuit to cool the oil-immersed transformer, it injects the high-temperature waste heat of the oil-immersed transformer as a "heat source" into the cooling circuit of the power conversion equipment, thereby reheating the cooling medium that has already absorbed heat from the power conversion equipment. This actually increases the temperature difference between the inlet medium of the external heat dissipation equipment and the environment. This "heat-assisted heating" design direction is completely opposite to the conventional technical teaching of "independent heat dissipation for each circuit and avoidance of thermal coupling," overcoming the technical bias that has long existed in the minds of those skilled in the art.

[0029] For ease of explanation, such as Figures 1 to 3 As shown, this application discloses a coupled heat dissipation system, which may include an oil-immersed transformer 1, a power conversion device 2, and an intermediate heat exchange unit 3. The oil-immersed transformer 1 is connected to a first cooling circuit 4, which is equipped with a first pump 41, and a first cooling medium circulates within the first cooling circuit 4. The power conversion device 2 is connected to a second cooling circuit 5, which is equipped with a second pump 51, and a second cooling medium circulates within the second cooling circuit 5. An external heat dissipation device 6 is connected in series with the second cooling circuit 5. The intermediate heat exchange unit 3 has a first heat exchange channel 31 and a second heat exchange channel 32. The first cooling circuit 4 is connected to the first heat exchange channel 31, and the second cooling circuit 5 is connected to the second heat exchange channel 32. Along the flow direction of the second cooling medium, the second heat exchange channel 32 is located upstream of the external heat dissipation device 6. The external heat dissipation device 6 is configured to release the heat carried by the second cooling medium to the ambient air; the first cooling circuit 4 is connected to the first heat exchange channel 31, and the second cooling circuit 5 is connected to the second heat exchange channel 32; along the flow direction of the second cooling medium, the power conversion device 2, the second heat exchange channel 32 and the external heat dissipation device 6 are arranged in sequence, so that after the second cooling medium absorbs the heat generated by the power conversion device 2, it flows through the second heat exchange channel 32, and absorbs the heat from the first cooling medium in the intermediate heat exchange unit 3 before entering the external heat dissipation device 6, so as to increase the temperature difference between the second cooling medium entering the external heat dissipation device 6 and the ambient air.

[0030] The overall working path of this coupled heat dissipation system is as follows: the heat generated by the oil-immersed transformer 1 during operation is carried by its internal first cooling medium (transformer oil) and circulates through the first cooling circuit 4 to the intermediate heat exchange unit 3; the heat generated by the power conversion device 2 during operation is carried by its internal second cooling medium (coolant) and circulates through the second cooling circuit 5 through the power conversion device 2, the intermediate heat exchange unit 3, and the external heat dissipation device 6. When the second cooling medium flows through the intermediate heat exchange unit 3, it can selectively absorb heat from the first cooling medium, thereby carrying the heat from the oil-immersed transformer 1 to the external heat dissipation device 6 for discharge, thus achieving the coupling of transformer heat dissipation and PCS heat dissipation.

[0031] This application breaks through technical bias by actively introducing the high-temperature waste heat of the oil-immersed transformer 1 into the second cooling circuit 5 of the power conversion device 2 through the first cooling circuit 4. This not only preheats the oil-immersed transformer 1 but also utilizes the high-temperature heat energy of the oil-immersed transformer 1 to "reheat" the second cooling medium that has already absorbed heat from the power conversion device 2. This further increases the temperature of the cooling medium entering the external heat dissipation device 6, increasing the temperature difference between it and the ambient air, thereby significantly improving the heat dissipation efficiency of the external heat dissipation device 6. Therefore, this application enhances the heat dissipation capacity of the power conversion device 2 by utilizing the originally discarded waste heat of the oil-immersed transformer 1 without increasing the specifications of the external heat dissipation device 6, achieving a synergistic heat dissipation effect of "heat assisting cooling." This effectively solves the technical problem of the prominent heat dissipation bottleneck of the converter-boost integrated machine in high power density scenarios. Simultaneously, this coupled heat dissipation system eliminates the need for additional large-plate heat sinks or forced air cooling devices for the oil-immersed transformer 1, and also eliminates the need to increase the heat dissipation area of ​​the power conversion device 2 separately. This helps simplify the overall layout and reduce the size, providing strong support for the miniaturization and high-efficiency design of the equipment.

[0032] The oil-immersed transformer 1 is the core device for voltage conversion in the energy storage system. A first cooling medium circulates within the oil-immersed transformer 1, while a second cooling medium circulates within the power conversion device 2. The first cooling medium can be insulating oil, such as mineral insulating oil, natural ester insulating oil, synthetic ester insulating oil, or other insulating liquids suitable for oil-immersed transformers. The second cooling medium can be a non-flammable or flame-retardant coolant, such as a water-based coolant containing flame-retardant additives, an aqueous solution of ethylene glycol, an aqueous solution of propylene glycol, a fluorinated liquid, a silicon-based coolant, or other cooling media with good heat exchange performance and meeting safety requirements. The specific type, concentration, and parameters of the cooling medium can be selected according to the application scenario, temperature range, antifreeze requirements, insulation requirements, and fire protection requirements; this application embodiment does not limit these aspects.

[0033] The oil-immersed transformer 1 is connected to the first cooling circuit 4. A first cooling medium circulates within the first cooling circuit 4. For example, the first cooling medium is transformer oil. One end of the first cooling circuit 4 is connected to the oil outlet of the oil-immersed transformer 1, and the other end is connected to the inlet of the first heat exchange channel 31 of the intermediate heat exchange unit 3. The outlet of the first heat exchange channel 31 returns to the oil inlet of the oil-immersed transformer 1 through a pipeline, thus forming a closed loop. That is, the first cooling circuit 4 is connected to the first heat exchange channel 31.

[0034] The first cooling circuit 4 is equipped with a first pump 41, which drives the first cooling medium to circulate within the first cooling circuit 4. For example, the first pump 41 is an oil pump, installed on the pipeline between the oil outlet of the oil-immersed transformer 1 and the inlet of the first heat exchange channel 31. The first pump 41 can be a fixed-frequency pump or a variable-frequency pump; when a variable-frequency pump is used, the flow rate of the first cooling medium can be changed by adjusting its driving frequency.

[0035] The first cooling circuit 4 is also connected in series with a first valve 42. The first valve 42 is disposed on the pipeline of the first cooling circuit 4 and is used to control the opening and closing of the first cooling circuit 4 or to regulate the flow rate of the first cooling medium. Exemplarily, the first valve 42 is a solenoid valve or an electric regulating valve, which can be opened, closed or adjusted under the control of a controller. The first valve 42 can be disposed downstream or upstream of the first pump 41, and this embodiment of the application does not limit this.

[0036] The power conversion device 2 is connected to the second cooling circuit 5. A second cooling medium circulates within the second cooling circuit 5. Exemplarily, the second cooling medium is deionized water, an aqueous solution of ethylene glycol, or other coolants with good thermal conductivity and flow properties.

[0037] One end of the second cooling circuit 5 is connected to the coolant outlet of the power conversion device 2, and the other end is connected to the inlet of the second heat exchange channel 32 of the intermediate heat exchange unit 3. The outlet of the second heat exchange channel 32 is connected to the inlet of the external heat dissipation device 6 through a pipeline, and the outlet of the external heat dissipation device 6 returns to the coolant inlet of the power conversion device 2 through a pipeline, thus forming a closed loop. That is, the second cooling circuit 5 is connected to the second heat exchange channel 32.

[0038] The second cooling circuit 5 is equipped with a second pump 51, which drives the second cooling medium to circulate within the second cooling circuit 5. For example, the second pump 51 is a water pump, which can be installed on the pipeline between the outlet of the external heat dissipation device 6 and the coolant inlet of the power conversion device 2, or on the pipeline between the coolant outlet of the power conversion device 2 and the inlet of the second heat exchange channel 32. The second pump 51 can be a fixed-frequency pump or a variable-frequency pump; when a variable-frequency pump is used, the flow rate of the second cooling medium can be changed by adjusting its driving frequency.

[0039] The second cooling circuit 5 is also connected in series with a second valve 52. The second valve 52 is disposed on the pipeline of the second cooling circuit 5 and is used to control the on / off state of the second cooling circuit 5 or to regulate the flow rate of the second cooling medium. For example, the second valve 52 is a solenoid valve or an electric regulating valve.

[0040] Along the flow direction of the second cooling medium, the power conversion device 2, the second heat exchange channel 32, and the external heat dissipation device 6 are arranged sequentially. Specifically, driven by the second pump 51, the second cooling medium first flows through the power conversion device 2, absorbing the heat generated during its operation; then it flows through the second heat exchange channel 32, exchanging heat with the first cooling medium flowing through the first heat exchange channel 31 in the intermediate heat exchange unit 3; finally, it flows through the external heat dissipation device 6, releasing the heat it carries into the ambient air. That is, along the flow direction of the second cooling medium, the second heat exchange channel 32 is located upstream of the external heat dissipation device 6.

[0041] The technical significance of this sequential arrangement is as follows: the second cooling medium first flows through the power conversion device 2, where its temperature is lowest and the temperature difference between it and the power modules is greatest. Therefore, it can obtain the maximum heat exchange driving force, which is beneficial for fully absorbing the heat generated by the power conversion device 2. Then, the second cooling medium, now at a higher temperature, flows through the second heat exchange channel 32, further absorbing heat from the first cooling medium in the intermediate heat exchange unit 3. Finally, the second cooling medium, reaching its highest temperature, enters the external heat dissipation device 6, releasing the heat to the ambient air. This sequential arrangement of "first absorbing heat from the PCS, then absorbing heat from the transformer, and finally releasing it uniformly" maximizes the utilization of the second cooling medium's temperature rise potential, improving the overall system's thermal efficiency.

[0042] The intermediate heat exchange unit 3 is one of the core components of this application embodiment. The intermediate heat exchange unit 3 has a first heat exchange channel 31 and a second heat exchange channel 32. The first heat exchange channel 31 and the second heat exchange channel 32 are isolated from each other and not interconnected, but they have good thermal conductivity, enabling heat exchange between the fluid in the first heat exchange channel 31 and the fluid in the second heat exchange channel 32 through heat transfer between the two channels. A first cooling medium can flow through the first heat exchange channel 31 of the intermediate heat exchange unit 3, and a second cooling medium can flow through the second heat exchange channel 32 of the intermediate heat exchange unit 3. The first cooling medium and the second cooling medium undergo non-contact heat exchange within the intermediate heat exchange unit 3.

[0043] It should be noted that the "non-contact heat exchange" described in this article refers to the first and second cooling media being located in separate, isolated heat exchange channels, without mixing, and heat transfer occurring through the heat exchange walls. This non-contact heat exchange method avoids cross-contamination between the transformer insulating oil and the coolant on the power conversion equipment side, thus ensuring the insulation performance of the oil-immersed transformer 1 and the cooling reliability of the power conversion equipment 2. Furthermore, even if the pressure, flow rate, or temperature of the cooling medium on one side fluctuates, it is less likely to directly affect the quality of the medium on the other side, which is beneficial for improving system safety.

[0044] The intermediate heat exchange unit 3 can be a plate heat exchanger, a shell-and-tube heat exchanger, a coaxial heat exchanger, a microchannel heat exchanger, or other heat exchangers capable of non-contact heat exchange between two media. In some embodiments, the intermediate heat exchange unit 3 is selected as a plate heat exchanger. Plate heat exchangers are characterized by their compact structure, high heat exchange efficiency, and small footprint, making them suitable for applications where the internal space of the converter-boost integrated unit is limited. In other embodiments, the intermediate heat exchange unit 3 is selected as a shell-and-tube heat exchanger. Shell-and-tube heat exchangers have good pressure resistance and a wide range of adaptable media, making them suitable for scenarios where the first cooling medium is insulating oil and the system requires high mechanical reliability. The specific heat exchange area, number of channels, flow arrangement, pressure rating, sealing material, and installation method of the intermediate heat exchange unit 3 can be designed according to the capacity of the oil-immersed transformer 1, the heat consumption of the power conversion equipment 2, the ambient temperature, and the type of cooling medium.

[0045] In some embodiments, the first cooling circuit 4 may include oil passages inside the transformer tank, connecting pipes outside the tank, a first heat exchange channel 31 of the intermediate heat exchange unit 3, a first pump 41, and a first valve 42. During operation of the oil-immersed transformer 1, the heat generated by the windings, core, and structural components is transferred to the first cooling medium inside the tank. The first pump 41 drives the first cooling medium to flow out of the oil-immersed transformer 1, through the connecting pipes, and into the first heat exchange channel 31 of the intermediate heat exchange unit 3. After releasing heat to the second cooling medium in the second heat exchange channel 32 within the first heat exchange channel 31, the first cooling medium then flows back into the oil-immersed transformer 1. The first valve 42 can be used to open, close, or regulate the flow rate of the first cooling medium in the first cooling circuit 4.

[0046] The first pump 41 can be an oil pump, a canned motor pump, a magnetic pump, or other pumps suitable for circulating insulating oil. The first valve 42 can be an electric valve, a proportional valve, a regulating valve, a shut-off valve, a three-way valve, or other valves capable of regulating or cutting off the flow path. In some embodiments, the first valve 42 is located on the outlet side of the first pump 41 to regulate the flow rate of the first cooling medium output by the first pump 41. In other embodiments, the first valve 42 is located on the inlet side of the first pump 41, or at the inlet or outlet of the first heat exchange channel 31 of the intermediate heat exchange unit 3. This application does not limit this aspect.

[0047] In some embodiments, the second cooling circuit 5 may include a liquid cooling channel within the power conversion device 2, connecting pipes, a second heat exchange channel 32 of the intermediate heat exchange unit 3, an external heat dissipation device 6, a second pump 51, and a second valve 52. The power conversion device 2 includes power devices, which may include IGBTs, MOSFETs, SiC power modules, diode modules, inductors, bus capacitors, DC buses, AC buses, or other heat-generating components. The liquid cooling channel is thermally coupled to the power devices, and the second cooling medium absorbs the heat generated by the power devices as it flows through the liquid cooling channel. The second cooling medium, after absorbing heat, continues to flow through the second heat exchange channel 32 of the intermediate heat exchange unit 3, where it can absorb heat from the first cooling medium, and then enters the external heat dissipation device 6 to release the heat it carries into the ambient air.

[0048] In some embodiments, the external heat dissipation device 6 can be a wind-liquid heat exchanger. The external heat dissipation device 6 is connected in series in the second cooling circuit 5 and configured to release the heat carried by the second cooling medium to the ambient air. The external heat dissipation device 6 may include a heat exchange core 61 and a fan 62. The heat exchange core 61 may include a finned tube heat exchange core, a microchannel heat exchange core, a plate-fin heat exchange core, or other heat exchange cores suitable for liquid-air heat exchange. The fan 62 drives ambient air to flow through the heat exchange core 61, so that the heat in the second cooling medium is transferred to the air through the heat exchange core 61 and discharged outside the system. The fan 62 can be an axial flow fan, a centrifugal fan, a mixed flow fan, or other types of fans.

[0049] In this embodiment, the external heat dissipation device 6 can be arranged in the area where the oil-immersed transformer 1 is located. Specifically, the external heat dissipation device 6 can be set on the top, side, or adjacent to the oil-immersed transformer 1. The external heat dissipation device 6 can be in any direction of the oil-immersed transformer 1, and the distance between the external heat dissipation device 6 and the oil-immersed transformer 1 can be adjusted according to actual needs, for example, it can be any value between 10cm and 500cm.

[0050] In this way, the external heat dissipation device 6 no longer occupies the top or internal space of the power conversion device 2, which helps to reduce the height, width, or overall volume of the power conversion device 2, making it easier to achieve miniaturization, modularization, and standardization. Simultaneously, the external heat dissipation device 6 is physically isolated from the electronic cavity of the power conversion device 2, preventing hot air exhausted from the external heat dissipation device 6 from flowing back to the air inlet of the electronic cavity of the power conversion device 2, thereby reducing the risk of thermal short circuits. Figure 1 As shown, the external heat dissipation device 6 is installed on top of the oil-immersed transformer 1, thereby saving space.

[0051] It should be noted that the "electronic cavity" mentioned in this article can be understood as the space within the power conversion device 2 where control boards, drive boards, communication modules, low-voltage power supplies, sensors, relays, or other temperature-sensitive electronic components are arranged. The electronic cavity typically needs to maintain a low intake air temperature and a relatively stable operating environment. By physically isolating the external heat dissipation device 6 from the electronic cavity, the impact of high-temperature air on the electronic cavity can be reduced, improving the lifespan of electronic components and the reliability of system operation.

[0052] In some embodiments, the external heat dissipation device 6 is disposed on top of the oil-immersed transformer 1. The oil-immersed transformer 1 typically has a large top mounting area; placing the external heat dissipation device 6 on top of it fully utilizes the structural space of the oil-immersed transformer 1 and reduces the space occupied on the side of the power conversion device 2. The external heat dissipation device 6 can be fixed to the top of the oil-immersed transformer 1 by means of brackets, frames, mounting beams, or fasteners. To reduce the impact of vibration on the oil-immersed transformer 1, vibration damping pads, rubber vibration isolation components, or elastic connectors can be provided between the external heat dissipation device 6 and the mounting bracket.

[0053] In other embodiments, the external heat dissipation device 6 is disposed on the side of the oil-immersed transformer 1 in the horizontal direction. For example, the external heat dissipation device 6 can be arranged adjacent to the finned heat sink area of ​​the oil-immersed transformer 1, or replace part of the installation position of the traditional finned heat sink. This side-mounted arrangement reduces the overall height, making it suitable for height-constrained containers, cabins, or skid-mounted equipment. In still other embodiments, the external heat dissipation device 6 is disposed adjacent to the oil-immersed transformer 1, for example, on a bracket on the rear, front, or side of the oil-immersed transformer 1 in the horizontal direction. The distance between the external heat dissipation device 6 and the oil-immersed transformer 1 can be adjusted according to actual needs, for example, it can be any value between 10cm and 500cm. This arrangement facilitates maintenance personnel's external access to the heat exchange core 61 and the fan 62, making it convenient to clean the heat exchange core 61, replace the fan 62, or inspect the piping.

[0054] In some embodiments, the second heat exchange channel 32 of the intermediate heat exchange unit 3 is located upstream of the external heat dissipation device 6, along the flow direction of the second cooling medium. That is, the second cooling medium first flows through the second heat exchange channel 32 of the intermediate heat exchange unit 3 before entering the external heat dissipation device 6. With this flow arrangement, heat from the oil-immersed transformer 1 can be transferred to the second cooling medium first, and then uniformly discharged to the ambient air by the same external heat dissipation device 6. In this way, the oil-immersed transformer 1 and the power conversion device 2 can share the heat dissipation terminal or external heat dissipation device on the power conversion device side, thereby reducing the number of independent heat dissipation components and lowering system complexity and thermal management energy consumption.

[0055] In other embodiments, the second cooling medium may first flow through the liquid cooling channel of the power conversion device 2, then through the second heat exchange channel 32 of the intermediate heat exchange unit 3, and finally enter the external heat dissipation device 6. In this case, after absorbing heat from the power conversion device 2, the second cooling medium absorbs heat transferred from the oil-immersed transformer 1 side through the intermediate heat exchange unit 3, and is finally dissipated by the external heat dissipation device 6. In still other embodiments, the second cooling circuit 5 can be configured with bypass branches according to the system operating mode, allowing the second cooling medium to selectively flow through the intermediate heat exchange unit 3, the external heat dissipation device 6, or a specific power conversion device 2 under different operating conditions. This application does not limit this aspect.

[0056] like Figure 4 As shown, in some embodiments, there are multiple power conversion devices 2. Multiple power conversion devices 2 are connected in parallel to the second cooling circuit 5 and share an intermediate heat exchange unit 3 and / or an external heat dissipation device 6. Exemplarily, the multiple power conversion devices 2 can be a first power conversion device 2a, a second power conversion device 2b, and a third power conversion device 2c. The second cooling circuit 5 includes a main liquid supply line, a main liquid return line, and multiple branches. Each power conversion device is connected to the main liquid supply line and the main liquid return line through a corresponding branch. The second cooling medium, driven by the second pump 51, enters the main liquid supply line, then enters the liquid cooling channel of each power conversion device, absorbs the heat generated by each power conversion device, and then flows into the main liquid return line, passing through the intermediate heat exchange unit 3 and the external heat dissipation device 6.

[0057] To regulate the cooling flow rate of multiple power conversion devices 2, in some embodiments, each power conversion device 2 is provided with a corresponding branch valve 53. The branch valve 53 is configured to regulate the flow rate of the second cooling medium entering the corresponding power conversion device 2. The branch valve 53 can be an electrically adjustable valve, a proportional valve, a balancing valve, a switching valve, or other valve components. The controller 7 can adjust the opening degree of the corresponding branch valve 53 according to the operating load, inlet and outlet temperatures, power device temperatures, second cooling medium temperatures, or heat dissipation requirements of each power conversion device 2, thereby allowing high-load power conversion devices to receive a larger cooling flow rate, while low-load or shut-down power conversion devices receive a smaller cooling flow rate or have their liquid supply stopped. This improves the flow distribution efficiency of the second cooling medium and reduces the ineffective power consumption of the second pump 51.

[0058] In some embodiments, multiple power conversion devices 2 can share a single intermediate heat exchange unit 3 and an external heat dissipation device 6. This approach is simple in structure and suitable for scenarios where multiple power conversion devices have similar heat dissipation and are centrally located. In other embodiments, multiple power conversion devices 2 can share a single intermediate heat exchange unit 3, but multiple external heat dissipation devices 6 are provided. The multiple external heat dissipation devices 6 can be arranged in parallel to improve the system's heat dissipation capacity and reduce the noise of individual fans. In still other embodiments, multiple power conversion devices 2 can share a single external heat dissipation device 6, but each corresponds to a multiple intermediate heat exchange unit 3, so as to achieve thermal coupling with multiple oil-immersed transformers or multiple transformer oil circulation branches respectively. The above structures can be flexibly selected according to the capacity, number of devices, and installation space of the integrated converter and step-up unit.

[0059] like Figure 5As shown, in some embodiments, the coupled heat dissipation system may further include a controller 7. The controller 7 is communicatively connected to the first pump 41, the second pump 51, the external heat dissipation device 6, the first valve 42, and / or the second valve 52, and is configured to control the operating status of the first pump 41, the second pump 51, the external heat dissipation device 6, the first valve 42, and / or the second valve 52 based on the temperature Toil of the first cooling medium, the temperature Tout of the second cooling medium, and / or the ambient temperature Tamb. In this embodiment, the temperature Toil of the first cooling medium can be obtained by measuring the temperature of the oil-immersed transformer 1 and / or the first cooling circuit 4. Taking the oil-immersed transformer 1 as an example, the temperature of the first cooling medium at the top, middle, or bottom layer of the oil-immersed transformer 1 can be measured. It should be noted that the temperature of the first cooling medium inside the oil-immersed transformer 1 exhibits significant stratification in the height direction; the first cooling medium naturally rises due to its decreasing density and accumulates at the top of the oil-immersed transformer 1. Under rated load, the temperature Toil of the top-layer first cooling medium is typically about 20°C higher than the temperature Toil of the bottom-layer first cooling medium. Therefore, to obtain better control accuracy, the temperature Toil of the first cooling medium is obtained by measuring the temperature of the top-layer first cooling medium of the oil-immersed transformer 1. Similarly, the temperature Tout of the second cooling medium can be obtained by measuring the temperature of the power conversion device 2 and / or the second cooling circuit 5. Taking the power conversion device 2 as an example, the temperature at the inlet and outlet of the power conversion device 2 can be measured. It should be noted that the core purpose of this embodiment is to adjust the temperature difference of the external heat dissipation device 6. Therefore, to obtain better control accuracy, the temperature Tout of the second cooling medium is obtained by measuring the temperature of the second cooling medium at the outlet of the power conversion device 2.

[0060] Controller 7 can be a standalone thermal management controller or integrated into the main controller of the converter-boost integrated unit, converter controller, transformer substation controller, energy management system, or station-level control system. Controller 7 may include a processor, memory, communication interface, analog input module, digital input module, relay output module, or PWM control module. Controller 7 can communicate with the first pump 41, the second pump 51, external cooling equipment 6, and valves via CAN, RS485, Ethernet, Modbus, PROFIBUS, wireless communication, or other communication methods. Controller 7 can also control the start / stop and speed of pumps, fans, or valves via hard-wired signals.

[0061] In some embodiments, the coupled heat dissipation system may further include temperature sensors. The temperature sensors may include a first temperature sensor, a second temperature sensor, a third temperature sensor, and an ambient temperature sensor. The first temperature sensor is used to detect the temperature Toil of the first cooling medium inside the oil-immersed transformer 1 or in the first cooling circuit 4. The second temperature sensor is used to detect the temperature Tout of the second cooling medium in the second cooling circuit 5, for example, the temperature of the second cooling medium at the outlet of the power conversion device 2, the outlet of the intermediate heat exchange unit 3, or the inlet of the external heat dissipation device 6. The third temperature sensor may be used to detect the temperature of the power device or the liquid cooling plate. The ambient temperature sensor is used to detect the external ambient temperature Tamb. The controller 7 may execute different control strategies based on the above temperature information.

[0062] like Figure 6 As shown, in some embodiments, the controller 7 is further configured to execute a first mode. The first mode can be a collaborative heat dissipation mode, or a high-temperature heat dissipation mode or a combined heat dissipation mode. In the first mode, when the temperature Toil of the first cooling medium is not lower than a first set temperature Toilset1 and / or the temperature Tout of the second cooling medium is not lower than a second set temperature Toutset, the controller 7 activates the first pump 41, the second pump 51, and the external heat dissipation device 6, causing the first cooling medium to release heat to the second cooling medium through the intermediate heat exchange unit 3, and causing the second cooling medium to release heat to the ambient air through the external heat dissipation device 6. The first set temperature Toilset1 is greater than the second set temperature Toutset.

[0063] Specifically, when the oil-immersed transformer 1 operates and generates heat, the first cooling medium absorbs the heat generated by the windings and core within the transformer 1. When the temperature of the first cooling medium reaches a first set temperature (Toilset1), it indicates that the oil-immersed transformer 1 has a heat dissipation requirement. The controller 7 starts the first pump 41, causing the high-temperature first cooling medium to flow through the first heat exchange channel 31 of the intermediate heat exchange unit 3. Simultaneously, the controller 7 starts the second pump 51, causing the second cooling medium to flow through the second heat exchange channel 32 of the intermediate heat exchange unit 3 and the external heat dissipation device 6. The first cooling medium transfers heat to the second cooling medium within the intermediate heat exchange unit 3. After entering the external heat dissipation device 6, the second cooling medium releases heat into the ambient air under the action of the airflow driven by the external heat dissipation device 6. Thus, the heat from the oil-immersed transformer 1 is discharged to the external environment via the first cooling medium, the intermediate heat exchange unit 3, the second cooling medium, and the external heat dissipation device 6.

[0064] When the power conversion device 2 is operating simultaneously, the second cooling medium also absorbs the heat generated by the power devices in the power conversion device 2. At this time, the heat carried by the second cooling medium includes the heat from the power conversion device 2 itself and the heat transferred from the oil-immersed transformer 1. The external heat dissipation device 6 can serve as a shared heat dissipation terminal for both, discharging both types of heat into the ambient air. Compared to a scheme where the oil-immersed transformer 1 and the power conversion device 2 each have independent heat dissipation systems, this embodiment can reduce the number of heat sinks or lower the specifications of individual heat sinks, simplify the system structure, and improve the integration of the thermal management system.

[0065] In the first mode, the controller 7 can dynamically adjust the rotation speed of the external heat dissipation device 6 based on the temperatures of the first cooling medium (Toil), the second cooling medium (Tout), and the ambient temperature (Tamb). For example, when the temperatures of the first and second cooling media (Toil and Tout) are low, the controller 7 can reduce the rotation speed of the external heat dissipation device 6 to reduce noise and fan energy consumption; when the temperatures of the first or second cooling media (Toil and Tout) increase, the controller 7 can increase the rotation speed of the external heat dissipation device 6 to enhance its air-side heat exchange capacity. When the ambient temperature (Tamb) is low, the controller 7 can appropriately reduce the rotation speed of the external heat dissipation device 6; when the ambient temperature (Tamb) is high, the controller 7 can increase the rotation speed of the external heat dissipation device 6 or start it earlier to maintain the cooling medium temperature within a safe range.

[0066] In some embodiments, when the temperature Toil of the first cooling medium of the oil-immersed transformer 1 continues to rise and the external heat dissipation device 6 has reached a preset output state, the controller 7 can increase the flow rate of the first pump 41 and / or the second pump 51 to enhance the heat exchange between the first and second cooling media. The preset output state here can be the external heat dissipation device 6 reaching its rated speed, maximum permissible speed, preset high-speed, or preset maximum power state. When the heat dissipation capacity of the external heat dissipation device 6 is close to its upper limit, increasing the flow rate of the first pump 41 can enhance the heat transfer capacity on the oil-immersed transformer 1 side, and increasing the flow rate of the second pump 51 can enhance the heat exchange capacity of the second cooling circuit 5 to the intermediate heat exchange unit 3 and the external heat dissipation device 6. When the temperature Toil of the first cooling medium is lower than the first set temperature Toilset1-γ1 and the temperature Tout of the second cooling medium is lower than the first set temperature Toutset-γ2, the first pump 41, the first valve 42, the second pump 51, the second valve 52, and the external heat dissipation device 6 are shut down to exit the first mode. Thus, in the first mode, through the coordinated control of the pumps and the external heat dissipation device 6, the system can meet the heat dissipation requirements while also considering energy consumption and noise.

[0067] In some embodiments, the controller 7 can employ a hierarchical control strategy. For example, when the temperature Toil of the first cooling medium is lower than the first set temperature Toilset1, the first pump 41 is stopped or operates at low speed, and the oil-immersed transformer 1 can maintain its temperature through natural oil circulation or low-flow circulation; when the temperature Toil of the first cooling medium reaches the first set temperature Toilset1, the first pump 41 starts at low speed; when the temperature Toil of the first cooling medium reaches a higher temperature threshold, the first pump 41 switches to medium or high speed operation. The second pump 51 and the external heat dissipation device 6 can also employ a similar hierarchical control method. This strategy is simple to implement, highly reliable, and suitable for engineering applications.

[0068] In other embodiments, controller 7 may employ a continuous adjustment strategy. For example, controller 7 may use a PID control algorithm to adjust the speeds of the first pump 41, the second pump 51, and the external heat dissipation device 6 based on the deviation between the target temperature and the actual temperature of the first cooling medium. A continuous adjustment strategy can reduce temperature fluctuations, decrease the impact of frequent start-stop cycles, and help reduce system noise. Controller 7 may also incorporate parameters such as ambient temperature Tamb, equipment load, grid power command, and historical temperature rise trends for feedforward control to further improve thermal management response speed.

[0069] like Figure 6 As shown, in some embodiments, the controller 7 is further configured to execute a second mode. The second mode can be a preheating mode, or a low-temperature start-up auxiliary mode. Specifically, when the temperature of the first cooling medium (Toil) of the oil-immersed transformer 1 is not higher than the third set temperature (Toilset2) and not lower than the fourth set temperature (Toilset3), the controller 7 starts the power conversion device 2, the second pump 51, and the first pump 41, and shuts down the external heat dissipation device 6 or reduces the output of the external heat dissipation device 6, so that the heat generated by the power conversion device 2 is transferred to the first cooling medium through the intermediate heat exchange unit 3 to preheat the oil-immersed transformer 1. The third set temperature (Toilset2) is lower than the first set temperature (Toilset1) and higher than the fourth set temperature (Toilset3).

[0070] Specifically, in low-temperature environments, the viscosity of the insulating oil in the oil-immersed transformer 1 may increase, reducing oil circulation performance and causing uneven temperature rise during startup, potentially affecting the transformer's operational stability. In this case, the heat generated after the power conversion device 2 starts up can be used to preheat the oil-immersed transformer 1. The controller 7 starts the second pump 51, causing the second cooling medium to flow through the liquid cooling channel of the power conversion device 2 and absorb heat generated by the power devices or other heat-generating components. Subsequently, the second cooling medium flows through the second heat exchange channel 32 of the intermediate heat exchange unit 3, transferring heat to the first cooling medium in the first heat exchange channel 31. Simultaneously, the controller 7 starts the first pump 41, causing the first cooling medium to circulate between the oil-immersed transformer 1 and the intermediate heat exchange unit 3, thereby gradually increasing the temperature of the insulating oil inside the oil-immersed transformer 1.

[0071] In the second mode, controller 7 shuts down external heat dissipation device 6 or reduces its output, ensuring that the heat carried by the second cooling medium is preferentially transferred to the first cooling medium rather than dissipated into the ambient air by external heat dissipation device 6. This allows the system to recover and reuse the heat from power conversion device 2, reducing the need for additional heating devices and lowering energy consumption during low-temperature startup. It should be noted that in the second mode, power conversion device 2 can operate at low power, standby power, preset heating power, or controlled operating conditions to generate an appropriate amount of heat. The specific operating mode of power conversion device 2 can be determined based on system safety requirements, power grid conditions, and control strategies.

[0072] In some embodiments, when the temperature Toil of the first cooling medium rises to a level not less than a third set temperature Toilset2+δ, the controller 7 exits the second mode and switches to the first mode or another mode according to the operating status of the power conversion device 2 and the oil-immersed transformer 1. For example, if both the oil-immersed transformer 1 and the power conversion device 2 are in operation and there is a need for heat dissipation, the controller switches to the first mode; if the power conversion device 2 is operating but the oil-immersed transformer 1 is not operating, the controller switches to the third mode; if the entire system shuts down, the controller shuts down the first pump 41, the second pump 51, and the external heat dissipation device 6.

[0073] like Figure 6 As shown, in some embodiments, the controller 7 is further configured to execute a third mode. The third mode can be an independent cooling mode for the power conversion device. When the oil-immersed transformer 1 is shut down or the temperature of the first cooling medium of the oil-immersed transformer 1 is lower than the fourth set temperature, the controller 7 shuts down the first pump 41 or disconnects the first cooling circuit 4, and starts the second pump 51 and the external heat dissipation device 6, so that the second cooling circuit 5 independently dissipates heat for the power conversion device 2.

[0074] Specifically, under certain operating conditions, the power conversion device 2 may need to operate independently or maintain standby cooling, while the oil-immersed transformer 1 is in a shutdown state. In this case, continuing to drive the first cooling medium circulation may cause unnecessary pump energy consumption, or transfer heat from the power conversion device 2 to the oil-immersed transformer 1, which does not require preheating. Based on this, the controller 7 can shut down the first pump 41, or cut off the first cooling circuit 4 via the first valve 42, preventing the first cooling medium from flowing through the intermediate heat exchange unit 3. The second pump 51 drives the second cooling medium to flow through the liquid cooling channel of the power conversion device 2 and the external heat dissipation device 6. The external heat dissipation device 6 drives ambient air to flow through the heat exchange core 61, thereby achieving independent heat dissipation for the power conversion device 2.

[0075] When the temperature of the first cooling medium Toil is not less than the fourth set temperature Toilset3+ε, shut down the second pump 51, the second valve 52 and the external heat dissipation device 6, and start the first pump 41 and the first valve 42 to exit the third mode.

[0076] In the third mode, the second heat exchange channel 32 of the intermediate heat exchange unit 3 may still be located in the second cooling circuit 5, but the heat exchange between the second and first cooling media is smaller because the first cooling circuit 4 is closed or the first cooling medium does not circulate. To reduce flow resistance, in some embodiments, a bypass branch may be provided in the second cooling circuit 5. When entering the third mode, the controller 7 opens the bypass valve, allowing the second cooling medium to bypass the intermediate heat exchange unit 3 and flow to the external heat dissipation device 6, thereby reducing the power consumption of the second pump 51. In other embodiments, the flow resistance of the intermediate heat exchange unit 3 is small, and the second cooling medium can continue to flow through the second heat exchange channel 32 without the need for a bypass branch.

[0077] It should be noted that the third set temperature Toutset2 can be used to determine whether preheating of the oil-immersed transformer 1 is necessary, and the fourth set temperature Toutset3 can be used to determine whether heat from the power conversion equipment 2 should be prevented from continuing to be transferred to the oil-immersed transformer 1, or whether the first cooling circuit 4 should be shut down to save energy. The first set temperature Toutset1, the second set temperature Toutset, the third set temperature Toutset2, and the fourth set temperature Toutset3 can all be set according to the type of the first cooling medium of the oil-immersed transformer 1, the allowable temperature rise, the cooling requirements of the power conversion equipment 2, the ambient temperature Tamb range, and the user's operating strategy.

[0078] like Figure 7As shown, in some embodiments, the first cooling circuit 4 is also connected to a spray structure 8. The spray structure 8 is located above or around the oil-immersed transformer 1 and is configured to spray the first cooling medium onto the oil-immersed transformer 1 under abnormal operating conditions. Since the third cooling medium can be a non-flammable or flame-retardant coolant, when the oil-immersed transformer 1 experiences abnormal temperature rise, thermal runaway, or fire risk, the first cooling medium in the first cooling circuit 4 can be used to spray and cool the surface of the oil-immersed transformer 1, or cover the transformer surface to isolate oxygen and suppress the spread of fire.

[0079] The spray structure 8 may include a spray pipe 81, a nozzle 82, and a spray valve 83. The spray pipe 81 may be arranged along the top edge, side, or circumference of the oil-immersed transformer 1. The nozzle 82 may be an atomizing nozzle, a fan-shaped nozzle, a conical nozzle, or other nozzles capable of forming a spray coverage area. The spray valve 83 is disposed on the spray pipe 81 and is used to control whether the second cooling medium enters the spray structure 8. The spray pipe 81 may be led out from the high-voltage side of the second cooling circuit 5, for example, from the outlet side of the second pump 51 or the main liquid supply line. Under abnormal operating conditions, the controller 7 opens the spray valve 83, the second pump 51 provides spray pressure, and the second cooling medium is sprayed onto the surface of the oil-immersed transformer 1 through the nozzle 82.

[0080] In some embodiments, the controller 7 can determine whether to enter an abnormal spraying condition based on the top oil temperature of the oil-immersed transformer 1, the winding temperature, the surface temperature of the oil tank, the status of the pressure relief device, the smoke sensor signal, the flame detection signal, or the gas relay signal. When the oil-immersed transformer 1 is detected to be in an abnormal temperature rise, thermal runaway, or fire risk state, the controller 7 opens the spray valve 83 and controls the first pump 41 to operate at a preset flow rate or preset pressure. If necessary, the controller 7 can also shut down the first pump 41, disconnect the first cooling circuit 4, stop the operation of the power conversion equipment 2, or issue a fault alarm. The spraying structure 8 can serve as an auxiliary safety measure to improve the safety of the system under extreme operating conditions.

[0081] It should be noted that when the spray structure 8 uses the first cooling medium for spraying, a non-flammable or flame-retardant coolant can be selected as the first cooling medium to avoid increasing the risk of combustion from the spray medium itself. In some embodiments, the first cooling medium may contain flame-retardant components, anti-corrosion components, and antifreeze components to meet the requirements of cooling, fire protection, and low-temperature operation. The installation of the spray structure 8 does not mean that the first cooling medium is in contact with the outer surface of the oil-immersed transformer 1 under normal operating conditions; under normal heat dissipation conditions, the first cooling medium still circulates within the first cooling circuit 4.

[0082] like Figure 7 and Figure 8As shown, in some embodiments, a filter device 9 is provided on the first cooling circuit 4 and / or the second cooling circuit 5. The filter device 9 can be used to filter particulate impurities, metal debris, colloids, or other contaminants in the cooling medium, preventing impurities from clogging the intermediate heat exchange unit 3, liquid cooling channel, valves, or spray structure 8. The filter device 9 may include a first filter 91 and a second filter 92. The first filter 91 is provided in the first cooling circuit 4 for filtering the first cooling medium; the second filter 92 is provided in the second cooling circuit 5 for filtering the second cooling medium.

[0083] The first filter 91 can be installed on the inlet side of the first pump 41 to protect the first pump 41 from damage by particulate impurities; it can also be installed on the inlet side of the first heat exchange channel 31 of the intermediate heat exchange unit 3 to prevent blockage of the heat exchange channel. The second filter 92 can be installed on the inlet side of the second pump 51, the inlet side of the power conversion device 2, the inlet side of the intermediate heat exchange unit 3, or the inlet side of the spray branch. The filter device 9 can adopt a removable filter element structure so that maintenance personnel can replace or clean the filter element regularly. In some embodiments, the filter device 9 can also be equipped with a differential pressure sensor, and when the pressure difference across the filter exceeds a preset threshold, the controller 7 issues a maintenance prompt or alarm signal.

[0084] The working process of the coupled heat dissipation system provided in the embodiments of this application will be described below with reference to an exemplary system structure.

[0085] In one exemplary embodiment, an oil-immersed transformer 1, a power conversion device 2, an intermediate heat exchange unit 3, and an external heat dissipation device 6 are arranged within the same integrated converter and step-up unit. The oil-immersed transformer 1 is located on one side of the integrated unit, and the power conversion device 2 is located on the other side. The external heat dissipation device 6 is disposed on top of the oil-immersed transformer 1, and the air outlet direction of the external heat dissipation device 6 is away from the air inlet of the electronic cavity of the power conversion device 2. The intermediate heat exchange unit 3 is disposed in the piping area between the oil-immersed transformer 1 and the power conversion device 2, facilitating the connection of the first cooling circuit 4 and the second cooling circuit 5, respectively. A first pump 41 and a first valve 42 are disposed on the first cooling circuit 4 outside the oil-immersed transformer 1. A second pump 51 and a second valve 52 are disposed on the second cooling circuit 5 outside the power conversion device 2. The second cooling medium flows sequentially through the liquid cooling channel of the power conversion device 2, the second heat exchange channel 32 of the intermediate heat exchange unit 3, the external heat dissipation device 6, and the second pump 51, and returns to the power conversion device 2.

[0086] When the converter-boost integrated unit operates under high temperature and high load conditions, the power devices of the power conversion equipment 2 generate a significant amount of heat, as do the windings and core of the oil-immersed transformer 1. The controller 7 enters the first mode after detecting that the temperature of the first cooling medium (Toil) is not lower than the first set temperature (Toilset1), or the temperature of the second cooling medium (Tout) is not lower than the second set temperature (Toutset). The first pump 41 drives the insulating oil to circulate between the oil-immersed transformer 1 and the intermediate heat exchange unit 3, while the second pump 51 drives the flame-retardant coolant to circulate between the power conversion equipment 2, the intermediate heat exchange unit 3, and the external heat dissipation device 6. The insulating oil releases heat to the flame-retardant coolant in the intermediate heat exchange unit 3, and the flame-retardant coolant releases heat to the ambient air in the external heat dissipation device 6. The fan 62 adjusts its speed according to the cooling medium temperature. Since the external heat dissipation device 6 is located in the area of ​​the oil-immersed transformer 1, the cabinet of the power conversion equipment 2 does not need to support the large external heat dissipation device 6, resulting in a more compact overall structure. Simultaneously, hot air is discharged away from the electronic cavity air inlet, reducing the risk of thermal short circuits. The first set temperature Toilset1 is greater than the second set temperature Toutset.

[0087] When the integrated converter and step-up transformer is in low-temperature start-up mode, the temperature of the insulating oil inside the oil-immersed transformer 1 is low. After the controller 7 detects that the temperature of the first cooling medium (Toil) is not higher than the third set temperature (Toilset2) and not lower than the fourth set temperature (Toilset3), it enters the second mode. The controller 7 controls the power conversion device 2 to operate at a preset low power. The second pump 51 drives the flame-retardant coolant to flow through the power conversion device 2 and absorb its operating heat. The first pump 41 drives the insulating oil to flow through the intermediate heat exchange unit 3. At this time, the fan 62 is off or running at low speed. The heat carried by the flame-retardant coolant is transferred to the insulating oil through the intermediate heat exchange unit 3, thereby preheating the oil-immersed transformer 1. After the insulating oil temperature rises to the preheating target temperature, the system exits the second mode. This method utilizes the heat loss of the power conversion device 2 to preheat the oil-immersed transformer 1, which can reduce the usage time of the independent electric heater or reduce the electric heating power.

[0088] When the oil-immersed transformer 1 is shut down while the power conversion equipment 2 still needs to operate or be in standby mode, the controller 7 detects that the temperature of the first cooling medium, Toil, is lower than the fourth set temperature, Toilset3, and enters the third mode. The controller 7 shuts down the first pump 41 or closes the first valve 42, cutting off the first cooling circuit 4 to avoid unnecessary circulation of insulating oil. The second pump 51 and the external heat dissipation device 6 start, and the second cooling medium independently removes the heat from the power conversion equipment 2 via the power conversion equipment 2 and the external heat dissipation device 6. In this mode, the system can both ensure heat dissipation of the power conversion equipment 2 and reduce the ineffective pump consumption on the side of the oil-immersed transformer 1. The third set temperature, Toilset2, is lower than the first set temperature, Toilset1, and higher than the fourth set temperature, Toilset3.

[0089] Combination Figure 3 See Figure 9 This application also provides a coupling heat dissipation method. This method can be applied to the coupling heat dissipation system in any of the above embodiments. The method includes: When the temperature Toil of the first cooling medium is higher than the temperature Tout of the second cooling medium, the following steps are performed: Step S1: The first pump 41 drives the first cooling medium to circulate in the first cooling circuit 4 of the oil-immersed transformer 1 to absorb the heat generated by the oil-immersed transformer 1.

[0090] Step S2: The second pump 51 drives the second cooling medium to circulate in the second cooling circuit 5 of the power conversion device 2 to absorb the heat generated by the power conversion device 2.

[0091] Step S3: The second cooling medium, after absorbing heat from the power conversion device 2, is guided to the second heat exchange channel 32 of the intermediate heat exchange unit 3, so that the second cooling medium exchanges heat with the first cooling medium from the first cooling circuit 4 within the intermediate heat exchange unit 3. The temperature of the first cooling medium is higher than that of the second cooling medium, so that the second cooling medium is further heated within the intermediate heat exchange unit 3. Step S4: The second cooling medium, which has been heated by the intermediate heat exchange unit 3, is guided to the external heat dissipation device 6, where the ambient air cools the second cooling medium. The second cooling medium flows sequentially through the power conversion device 2, the second heat exchange channel 32, and the external heat dissipation device 6 in the second cooling circuit 5, so that the temperature of the second cooling medium entering the external heat dissipation device 6 is higher than the temperature when it leaves the power conversion device 2.

[0092] See Figure 6 In some embodiments, the coupled heat dissipation method may include: obtaining the temperature Toil of the first cooling medium of the oil-immersed transformer 1 and / or the temperature Tout of the second cooling medium of the power conversion device 2. When the temperature Toil of the first cooling medium is not lower than a first set temperature Toilset1 and / or the temperature Tout of the second cooling medium is not lower than a second set temperature Toutset, it indicates that the first mode has been entered, and the controller 7 starts the first pump 41, the second pump 51, and the external heat dissipation device 6. The first pump 41 drives the first cooling medium to flow through the first heat exchange channel 31 of the intermediate heat exchange unit 3. The second pump 51 drives the second cooling medium to flow through the liquid cooling channel of the power conversion device 2, the second heat exchange channel 32 of the intermediate heat exchange unit 3, and the external heat dissipation device 6. The external heat dissipation device 6 drives ambient air to flow through the heat exchange core 61 of the external heat dissipation device 6. Thus, the heat from the oil-immersed transformer 1 and the power conversion device 2 can be uniformly discharged through the second cooling medium and the external heat dissipation device 6.

[0093] In the first mode, the controller 7 can also adjust the rotation speed of the external heat dissipation device 6 based on the temperature Toil of the first cooling medium, the temperature Tout of the second cooling medium, and / or the ambient temperature Tamb. When the temperature Toil of the first cooling medium of the oil-immersed transformer 1 continues to rise and the external heat dissipation device 6 reaches a preset output state, the controller 7 increases the flow rate of the first pump 41 and / or the second pump 51 to enhance the heat exchange between the first and second cooling media. If the temperature Tout of the second cooling medium is lower than a preset low-temperature threshold δ, the controller 7 can reduce the rotation speed of the second pump 51 or the external heat dissipation device 6 to reduce energy consumption and noise. If the temperature Toil of the first cooling medium or the temperature Tout of the second cooling medium exceeds a warning threshold, the controller 7 can issue an alarm, limit the output power of the power conversion device 2, or request the upstream system to reduce the load.

[0094] In some embodiments, the coupled heat dissipation method further includes obtaining the temperature Toil of the first cooling medium of the oil-immersed transformer 1. When the temperature Toil of the first cooling medium is not higher than the third set temperature Toilset2 and not lower than the fourth set temperature Toilset3, it indicates that the second mode has been entered. The controller 7 starts the power conversion device 2, the second pump 51 and the first pump 41, and shuts down the external heat dissipation device 6 or reduces the output of the external heat dissipation device 6. The heat generated by the power conversion device 2 is carried by the second cooling medium into the second heat exchange channel 32 of the intermediate heat exchange unit 3. The intermediate heat exchange unit 3 transfers the heat in the second cooling medium to the first cooling medium to preheat the oil-immersed transformer 1. This mode can improve the start-up conditions of the oil-immersed transformer 1 in low-temperature environments and improve the waste heat utilization rate of the power conversion device 2.

[0095] In some embodiments, the coupled heat dissipation method further includes indicating that a third mode has been entered when the oil-immersed transformer 1 is shut down or the temperature of the first cooling medium of the oil-immersed transformer 1 is lower than the fourth set temperature. The controller 7 shuts down the first pump 41 or disconnects the first cooling circuit 4, and starts the second pump 51 and the external heat dissipation device 6. The second cooling medium flows through the liquid cooling channel of the power conversion device 2 and the external heat dissipation device 6 to dissipate heat from the power conversion device 2. This mode is suitable for operating conditions where the oil-immersed transformer 1 does not require heat dissipation or does not need to participate in thermal coupling, thus reducing system energy consumption.

[0096] See Figure 4In some embodiments, when multiple power conversion devices 2 are connected in parallel to the second cooling circuit 5, the controller 7 adjusts the flow rate of the second cooling medium in the corresponding branch of each power conversion device 2 according to the operating load of each power conversion device 2, the temperature Tout of the second cooling medium, and / or the heat dissipation requirements. For example, when the output power of the first power conversion device 2a is higher than that of the second power conversion device 2b, the controller 7 can increase the opening of the valve 53 in the corresponding branch of the first power conversion device 2a and decrease the opening of the valve 53 in the corresponding branch of the second power conversion device 2b. In this way, the system can allocate cooling capacity as needed, avoiding overcooling or insufficient cooling in some branches.

[0097] See Figure 5 and 7 In some embodiments, when the oil-immersed transformer 1 is detected to be in a state of abnormal temperature rise, thermal runaway, or fire risk, the controller 7 sprays non-flammable or flame-retardant coolant onto the surface of the oil-immersed transformer 1 through the spray structure 8 to cool it down and / or isolate oxygen. During the spraying process, the controller 7 can control the second pump 51 to operate at a high flow rate and control the spray valve 83 according to the spray pressure or spraying time. If the abnormal state is resolved, the controller 7 can close the spray valve 83 and perform fault recording and maintenance prompts. If the abnormal state persists, the controller 7 can activate the fire protection system, disconnect the electrical connection, or send an alarm to the higher-level monitoring platform.

[0098] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. For example, the type of intermediate heat exchange unit 3, the number and location of external heat dissipation devices 6, the location of the first pump 41 and the second pump 51, the valve type, the control strategy, the type of cooling medium, and the pipeline connection method can all be adjusted according to actual application conditions. As long as these modifications or substitutions do not depart from the spirit and scope of the technical solutions of this application, they should all be covered within the scope of protection of this application.

Claims

1. A coupled heat dissipation system, characterized in that, include: An oil-immersed transformer (1) is connected to a first cooling circuit (4), which is equipped with a first pump (41) and a first cooling medium circulates within the first cooling circuit (4). A power conversion device (2) is connected to a second cooling circuit (5), which is equipped with a second pump (51) and a second cooling medium circulates within the second cooling circuit (5); an external heat dissipation device (6) is also connected in series in the second cooling circuit (5). The intermediate heat exchange unit (3) has a first heat exchange channel (31) and a second heat exchange channel (32). The first cooling circuit (4) is connected to the first heat exchange channel (31), and the second cooling circuit (5) is connected to the second heat exchange channel (32). Along the flow direction of the second cooling medium, the second heat exchange channel (32) is located upstream of the external heat dissipation device (6).

2. The coupled heat dissipation system as described in claim 1, characterized in that, The external heat dissipation device (6) is located on the top, side or near the oil-immersed transformer (1).

3. The coupled heat dissipation system as described in claim 2, characterized in that, If there are multiple power conversion devices (2), each power conversion device (2) is provided with a branch valve (53), and the branch valve (53) is configured to regulate the flow rate of the second cooling medium entering the corresponding power conversion device (2); The first cooling circuit (4) is connected in series with a first valve (42); The second cooling circuit (5) is connected in series with a second valve (52).

4. The coupled heat dissipation system as described in claim 3, characterized in that, It also includes a controller (7), which is communicatively connected to the first pump (41) in the first cooling circuit (4), the second pump (51) in the second cooling circuit (5), the external heat dissipation device (6), the first valve (42) and / or the second valve (52), and is configured to control the operating status of the first pump (41), the second pump (51), the external heat dissipation device (6), the first valve (42) and / or the second valve (52) according to the temperature of the first cooling medium, the temperature of the second cooling medium and / or the ambient temperature.

5. The coupled heat dissipation system as described in any one of claims 1 to 4, characterized in that, The first cooling circuit (4) is also connected to a spray structure (8), which is located above or around the oil-immersed transformer (1), and the spraying direction of the spray structure (8) is directed toward the oil-immersed transformer (1).

6. A coupled heat dissipation method, applied to the coupled heat dissipation system as described in any one of claims 1 to 5, characterized in that, include: When the temperature of the first cooling medium is higher than that of the second cooling medium, the first pump (41) drives the first cooling medium to circulate in the first cooling circuit (4) of the oil-immersed transformer (1); The second pump (51) drives the second cooling medium to circulate in the second cooling circuit (5) of the power conversion device (2); The second cooling medium, after absorbing the heat from the power conversion device (2), is guided to the second heat exchange channel (32) of the intermediate heat exchange unit (3). The second cooling medium, after being heated by the intermediate heat exchange unit (3), is guided to the external heat dissipation device (6) and cooled by the ambient air.

7. The method as described in claim 6, characterized in that, The method further includes: Obtain the temperature of the first cooling medium of the oil-immersed transformer (1) and / or the temperature of the second cooling medium of the power conversion device (2); When the temperature of the first cooling medium is not lower than the first set temperature and / or the temperature of the second cooling medium is not lower than the second set temperature, the first pump (41), the second pump (51) and the external heat dissipation device (6) are started; wherein the first set temperature is greater than the second set temperature; The first pump (41) drives the first cooling medium to flow through the first heat exchange channel (31) of the intermediate heat exchange unit (3). The second pump (51) drives the second cooling medium to flow through the liquid cooling channel of the power conversion device (2), the second heat exchange channel (32) of the intermediate heat exchange unit (3), and the external heat dissipation device (6). The external heat dissipation device (6) drives ambient air to flow through the external heat dissipation device (6).

8. The method as described in claim 7, characterized in that, The method further includes: When the temperature of the first cooling medium of the oil-immersed transformer (1) continues to rise and the external heat dissipation device (6) reaches the preset speed, the flow rate of the first pump (41) and / or the second pump (51) is gradually increased.

9. The method as described in claim 6, characterized in that, The method further includes: Obtain the temperature of the first cooling medium of the oil-immersed transformer (1); When the temperature of the first cooling medium is not higher than the third set temperature and not lower than the fourth set temperature, the power conversion device (2), the second pump (51) and the first pump (41) are started, and the external heat dissipation device (6) is turned off or the speed of the external heat dissipation device (6) is reduced. The third set temperature is lower than the first set temperature and higher than the fourth set temperature.

10. The method as described in claim 6, characterized in that, The method further includes: When the oil-immersed transformer (1) is shut down or the temperature of the first cooling medium of the oil-immersed transformer (1) is lower than the fourth set temperature, the first pump (41) is shut down. Start the second pump (51) and the external heat dissipation equipment (6).

11. The method as described in claim 6, characterized in that, The method further includes at least one of the following: When multiple power conversion devices (2) are connected in parallel to the second cooling circuit (5), the flow rate of the second cooling medium in the corresponding branch of each power conversion device (2) is adjusted according to the operating load of each power conversion device (2), the temperature of the second cooling medium and / or the heat dissipation requirements. When the oil-immersed transformer (1) is detected to be in an abnormal temperature rise, thermal runaway or fire risk state, the first cooling medium is sprayed onto the surface of the oil-immersed transformer (1) through the spray structure (8) to cool down and / or isolate oxygen, wherein the first cooling medium is a non-flammable cooling medium. After the second cooling medium absorbs the heat of the first cooling medium through the intermediate heat exchange unit (3), the second cooling medium enters the external heat dissipation device (6).

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