Cold starting device of oil-immersed water-cooled transformer

Abstract

The utility model relates to a cold starting device for an oil-immersed water-cooled transformer, which is a heating device for independently supplying heat and is used for heating radiating oil in an oil-water heat exchanger of the oil-immersed water-cooled transformer, so that the oil-immersed water-cooled transformer can be quickly heated. Comprising a heat source input pipeline, a heat source output pipeline or an electric heater arranged on an oil-water heat exchanger, a valve for controlling pipeline communication is further arranged on a main circulating cooling water path of the transformer, and the heat source input pipeline and the heat source output pipeline are correspondingly connected into the main circulating cooling water path of the transformer respectively and are communicated with an oil-water heat exchanger pipeline to form a heating circulating loop. According to the utility model, the cold start time of the oil-immersed water-cooled transformer in an extremely cold low-temperature environment can be shortened on the premise that the original heat dissipation performance of the transformer is not influenced, the transformer is protected from being locally overheated and damaged due to poor thermal cycle at a low temperature, and the application environment range of the transformer is expanded.

Description

Technical Field

[0001] The utility model relates to a cold starting device for a water-cooled transformer, in particular to a cold starting device for an oil-immersed water-cooled transformer, which is used to shorten the cold starting time of the oil-immersed water-cooled transformer when the oil-immersed water-cooled transformer is used in extremely cold areas, thereby broadening the application environment range of the oil-immersed water-cooled transformer. Background Art

[0002] When an oil-immersed transformer is cold-started in extremely cold regions, the viscosity of the cooling oil inside it increases due to the drop in oil temperature, which affects the oil's circulation within the transformer. If the transformer is operated under load at this time, the insufficient flow of the cooling oil within the transformer can easily lead to localized overheating of the transformer windings, potentially damaging the transformer. No-load cold-start operation can partially address this problem, but it still only works within a certain ambient temperature range and requires a long cold-start time.

[0003] In the existing technology, for oil-immersed self-cooling or oil-cooled transformers, there are currently designs that heat the transformer insulating oil by setting a heating stirring rod or quickly increase the transformer cooling oil temperature by setting a bypass circulation oil circuit, which to a certain extent expands the application environment range of the corresponding oil-immersed transformer.

[0004] However, oil-immersed water-cooled transformers have relatively higher requirements for ambient temperature. There is currently no good solution for their use in extremely cold areas and their ability to quickly start up and enter normal use. Utility Model Content

[0005] The purpose of the utility model is to solve the cold start problem of oil-immersed water-cooled transformers in extremely cold areas and expand the scope of its application environment. A cold start device for oil-immersed water-cooled transformers is proposed. Rapid warm-up is achieved by reasonably setting a heating device with independent heat supply, and heat from an external heat source is introduced into the main circulation cooling oil circuit of the transformer, thereby quickly raising the oil temperature of the cooling oil in the transformer. Moreover, since the heat source does not come from the transformer cooling oil itself, the risk of burning the coil due to local overheating is completely avoided, thereby realizing its application in cold start in extremely low temperature environment and effectively shortening its cold start time in low temperature environment.

[0006] The implementation method of the utility model is: a cold starting device for an oil-immersed water-cooled transformer, which is an independent heating device for heating the heat dissipation oil in the oil-water heat exchanger of the oil-immersed water-cooled transformer. The device includes heat source input and output pipelines or an electric heater arranged on the oil-water heat exchanger. A valve for controlling the connection of the pipeline is also provided on the main circulating cooling water line of the transformer. The heat source input and output pipelines are respectively connected to the main circulating cooling water line of the transformer, and are correspondingly connected to the hot water end and cold water end pipelines of the oil-water heat exchanger to form a heating circulation loop.

[0007] A buffer water tank is provided on the heating circulation loop. The cooling water input end of the buffer water tank is connected to the output pipeline of the main circulation cooling water circuit of the transformer through the first water pipe and the three-way valve in sequence, which is the heat source output pipeline. The cooling water output end of the buffer water tank is connected to the input pipeline of the main circulation cooling water circuit through the second water pipe, the heating water circulation pump and the third water pipe in sequence, which is the heat source input pipeline. The three-way valve is used to control the connectivity of the pipeline in the working state, and the other two ends are respectively connected to the output pipeline of the main circulation cooling water circuit. An electric heater is provided inside the buffer water tank.

[0008] One end of the heat source input and output pipelines are respectively connected to the input end and output end of the external heating interface, and the other end is respectively connected to the input and output pipelines of the transformer main circulation cooling water circuit through the corresponding three-way valve, directly introducing the external heat source into the oil-water heat exchanger. The two three-way valves are used to control the connectivity of the pipelines in the working state.

[0009] The cold start device directly heats the heat dissipating oil in the main circulation cooling oil circuit through the electric heater provided on the oil-water heat exchanger, and a water stop valve is provided on the main circulation cooling water circuit to control the connectivity of the pipeline in the working state.

[0010] Furthermore, the electric heater controls heating operation by supplying power to the heater.

[0011] Furthermore, the heat source input and output pipelines are arranged in parallel with the oil-water heat exchanger.

[0012] The beneficial effects of the utility model are:

[0013] 1. This utility model adds a cold-start heating device to an oil-immersed, water-cooled transformer using an independent heat source. During the cold-start process, when the transformer is powered off, heat from an electric heater or external source is transferred to the transformer's main cooling oil circuit via an oil-water heat exchanger, ultimately distributing it throughout the transformer. This device, which does not rely on heat generated by the transformer's own operation, avoids localized overheating and damage to the transformer coils caused by poor fluidity due to low cooling oil temperature. This allows oil-immersed, water-cooled transformers to achieve cold-start conditions where they would otherwise be unusable in extremely cold environments.

[0014] 2. The heating circulation loop designed in this utility model can completely cut off the main circulation cooling water circuit of the transformer when the cold machine is started, thereby blocking the flow loss of heat to the main circulation cooling water circuit through the oil-water exchanger and increasing the rising speed of the heat dissipating oil temperature in the transformer.

[0015] 3. The heating circulation loop designed by the utility model adopts valve control, which can only conduct the main circulation cooling water circuit under normal operating conditions of the transformer. The heating circulation loop is cut off and does not work, which does not affect the heat dissipation performance of the transformer.

[0016] 4. The heating circulation loop designed by this utility model adopts valve control, which can completely cut off the heat source input and output pipelines. When the components in the heating circulation loop (including the buffer water tank, electric heater or cold start circulating water pump, etc.) fail or the connected water pipes are blocked or leaking, it will not affect the normal use of the transformer.

[0017] 5. The heating circulation loop designed by the utility model can be composed of conventional mechanical components such as a buffer water tank, an electric heater, a circulating water pump, a three-way valve, and a water pipe. It has mature technology, low cost, high interchangeability and reliability, and a small size. It has little impact on the design and cost considerations of the oil-immersed water-cooled transformer and is also suitable for the modification of existing oil-immersed water-cooled transformers.

[0018] To sum up, the cold start device for oil-immersed water-cooled transformers of the utility model has a flexible design, does not affect the normal performance of the original transformer, and has low cost. It solves the problem of transformer loss caused by local overheating of oil-immersed water-cooled transformers in low temperature environments, thereby expanding its use environment range and shortening its cold start time in extremely cold environments, providing a suitable solution for the application of oil-immersed water-cooled transformers in extremely cold areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram showing the main connection relationship between the utility model and the oil-immersed water-cooled transformer in Example 1.

[0020] Figure 2 This is a schematic structural diagram of an alternative application example of Example 2 of the utility model in which no buffer water tank is provided.

[0021] Figure 3 This is a simplified structural diagram of an alternative application example of Example 3 of the utility model using an external heat source.

[0022] Figure 4 This is a timing logic diagram of the operation process of the cold start example of the oil-immersed water-cooled transformer in Example 1.

[0023] In the figure: 1. First water pipe; 2. Second water pipe; 3. Third water pipe; 4. Water stop valve; 5. Buffer water tank; 6. Electric heater; 7. Heater power supply; 8. Three-way valve; 9. Heating water circulation pump; 10. Main circulation cooling water circuit; 11. External interface of main circulation cooling water circuit; 12. Oil-water heat exchanger; 13. Main circulation cooling oil circuit; 14. Transformer body; 15. Transformer housing; 16. Transformer oil cavity; 17. Oil pillow; 18. Main circulation cooling oil pump; 19. External heating interface. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1:

[0026] According to the attached Figure 1 The utility model is a cold start device for an oil-immersed water-cooled transformer, which is used to realize a rapid heat-up of the oil-immersed water-cooled transformer. The oil-immersed water-cooled transformer includes a transformer body 14 arranged in a transformer housing 15. The cavity between the transformer body 14 and the transformer housing 15 is a transformer oil chamber 16. The transformer oil chamber 16 is filled with heat dissipation oil, and its top is connected to an oil pillow 17. An oil-water heat exchanger 12 is arranged between the cold oil end and the hot oil end of the transformer oil chamber 16 in a pipeline connection manner to form a main circulation cooling oil circuit 13, and is forced to circulate through a main circulation cooling oil pump 18. The hot water end and the cold water end of the oil-water heat exchanger 12 are respectively connected to the main circulation cooling water circuit external interface 11 by pipelines to form a main circulation cooling water circuit 10.

[0027] The oil-immersed, water-cooled transformer cold-start device is an independent heating device used to heat the cooling oil in the oil-water heat exchanger of the oil-immersed, water-cooled transformer. In this embodiment, the heating device includes heat source input and output pipelines arranged in parallel with the oil-water heat exchanger 12. The ends of the pipelines are connected to the hot water and cold water pipes of the oil-water heat exchanger 12, respectively, forming a heating circulation loop. A valve is also provided on the transformer's main circulating cooling water circuit 10 to control the connection of the pipelines.

[0028] The heating circulation loop is provided with a buffer water tank 5, and the cooling water input end of the buffer water tank 5 is connected to the output pipeline of the main circulation cooling water circuit 10 of the transformer through the first water pipe 1 and the three-way valve 8 in sequence, which is the heat source output pipeline. The cooling water output end of the buffer water tank 5 is connected to the input pipeline of the main circulation cooling water circuit 10 through the second water pipe 2, the heating water circulation pump 9 and the third water pipe 3 in sequence, which is the heat source input pipeline. The three-way valve 8 is used to control the connectivity of the pipeline in the working state, and its other two ends are respectively connected to the output pipeline of the main circulation cooling water circuit 10. The output pipeline and input pipeline of the main circulation cooling water circuit 10 are respectively connected to the external cooling equipment through the main circulation cooling water circuit external interface 11, which is used to transfer heat to the outside of the oil-immersed water-cooled transformer. The buffer water tank 5 is provided with an electric heater 6 inside, and the heating operation of the electric heater 6 is controlled by the heater power supply 7.

[0029] Attachment Figure 1 The direction of the dashed arrow is the flow direction of the cooling water in the main circulating cooling water circuit 10, and the direction of the solid arrow is the flow direction of the cooling water in the heating circulating pipeline.

[0030] In this embodiment, under normal operating conditions where the oil-immersed water-cooled transformer does not require a cold start, the three-way valve 8 isolates the first water pipe 1 from the main circulating cooling water path 10, the main circulating cooling water path 10 and the main circulating cooling water path external interface 11 remain unobstructed, the main circulating cooling oil pump 18 operates, and the hot oil in the transformer oil chamber 16 is cooled through the main circulating cooling oil path 13 where the oil-water heat exchanger 12 is located and then returns to the transformer oil chamber 16, thus circulating back and forth around the transformer body 14.

[0031] When the heating circuit is required during a cold start of an oil-immersed, water-cooled transformer, three-way valve 8 is used to shut off the passage between main cooling water circuit 10 and external interface 11. First water pipe 1 is connected, and cooling water in oil-water heat exchanger 12 flows through three-way valve 8 and first water pipe 1 into buffer water tank 5. Heater power supply 7 is energized, and electric heater 6 heats the cooling water in buffer water tank 5. Heating water circulation pump 9 operates, and the heated cooling water flows through second water pipe 2, pressurized by heating water circulation pump 9, and then returns to the cooling water input of oil-water heat exchanger 12. The heat in the heated cooling water is transferred through the oil-to-water heat exchanger 12 to the cooling oil in the primary cooling oil circuit 13. The primary cooling oil pump 18 operates, and the heated cooling oil flows into the cold oil terminal of the transformer housing 15. After fully circulating through the transformer, it transfers heat to the transformer body 14 before flowing out through the hot oil terminal of the transformer housing 15. After being pressurized by the primary cooling oil pump 18, it flows back into the oil-to-water heat exchanger 12 to be heated. This cycle repeats, extracting heat from the heated cooling water and transferring it to the transformer body 14. This rapidly heats the cooling oil in the transformer housing 15, resolving the problem of insufficient circulation caused by increased cooling oil viscosity due to low temperatures and avoiding damage to the transformer body 14 due to local overheating.

[0032] Example 2:

[0033] According to the attached Figure 2 When an external heat source capable of providing hot water is provided for the oil-immersed water-cooled transformer, the present invention can eliminate the need for a buffer water tank. Instead, an external heat supply interface 19 is provided to directly connect the external heat source via a pipeline to the main circulating cooling water circuit 10. One end of the heat source input and output pipelines are connected to the input and output ends of the external heat supply interface 19, respectively. The other ends are connected to the input and output pipelines of the transformer's main circulating cooling water circuit 10 via corresponding three-way valves, respectively. This introduces the external heat source directly into the oil-water heat exchanger 12. The two three-way valves are used to control the connection of the pipelines during operation. This embodiment also saves on the configuration of the electric heater 6, heater power supply 7, and heating water circulation pump 9.

[0034] Example 3:

[0035] According to the attached Figure 3 When a buffer water tank cannot be set up due to installation environment restrictions, the utility model can directly heat the heat dissipation oil in the main circulation cooling oil circuit 13 by setting the electric heater 6 on the oil-water heat exchanger 12, and set a water stop valve 4 on the main circulation cooling water circuit 10, and cut off the flow of cooling water in the main circulation cooling water circuit 10 through the water stop valve 4 to achieve the purpose of rapid cold start.

[0036] Attachment Figure 4This is an example of the cold start process for an oil-immersed, water-cooled transformer in Example 1 of the present invention, where the buffer water tank is equipped with an electric heater. When a 35kV / 80MVA oil-immersed, water-cooled transformer is cold started at an ambient temperature of -50°C, the oil-water heat exchanger is connected to the heating circuit via a three-way valve, while the oil-immersed, water-cooled transformer is powered off. The heating water circulating pump and the electric heater are then activated. The heating power of the electric heater is controlled by controlling the heater power supply to maintain the cooling water temperature in the buffer water tank at 60°C. The heat-dissipating oil is heated by the heat exchange in the oil-water heat exchanger and returned to the transformer oil chamber, causing the oil temperature there to continuously rise. When the oil temperature reaches 0°C, the transformer is powered on and operated at no load for 8 hours before switching to 20% load. After another 8 hours, the oil-immersed, water-cooled transformer cold start device is deactivated, the heater power is turned off, and the three-way valve isolates the heating circuit from the oil-water heat exchanger, connecting the oil-water heat exchanger to the main cooling water circuit. The heating water circulation pump stops running, and the oil-immersed water-cooled transformer can then operate normally within the rated current range. In this example, when the cooling oil temperature rises to ≥10 degrees Celsius, the water-cooled transformer cold start device of the present invention completes its operation prematurely and exits operation.

[0037] Example 2 adopts a design of connecting to an external heat source, and there is no need to set up an electric heater. Example 3 adopts a design of directly heating the cooling oil in the oil-water heat exchanger with an electric heater. The heat source control part has corresponding changes during the cold start of the oil-immersed water-cooled transformer, and the remaining control process steps are the same.

Claims

1. A cold starting device for an oil-immersed water-cooled transformer, characterized in that: The oil-immersed water-cooled transformer cold start device is an independent heating device for heating the heat dissipation oil in the oil-water heat exchanger of the oil-immersed water-cooled transformer. It includes heat source input and output pipelines or an electric heater arranged on the oil-water heat exchanger. A valve for controlling the connection of the pipeline is also provided on the main circulating cooling water line of the transformer. The heat source input and output pipelines are respectively connected to the main circulating cooling water line of the transformer, and are correspondingly connected to the hot water end and cold water end pipelines of the oil-water heat exchanger to form a heating circulation loop.

2. The cold starting device for an oil-immersed water-cooled transformer according to claim 1, characterized in that: A buffer water tank is provided on the heating circulation loop. The cooling water input end of the buffer water tank is connected to the output pipeline of the main circulation cooling water circuit of the transformer through the first water pipe and the three-way valve in sequence, which is the heat source output pipeline. The cooling water output end of the buffer water tank is connected to the input pipeline of the main circulation cooling water circuit through the second water pipe, the heating water circulation pump and the third water pipe in sequence, which is the heat source input pipeline. The three-way valve is used to control the connectivity of the pipeline in the working state, and the other two ends are respectively connected to the output pipeline of the main circulation cooling water circuit. An electric heater is provided inside the buffer water tank.

3. The cold starting device for an oil-immersed water-cooled transformer according to claim 1, characterized in that: One end of the heat source input and output pipelines are respectively connected to the input end and output end of the external heating interface, and the other end is respectively connected to the input and output pipelines of the transformer main circulation cooling water circuit through the corresponding three-way valve, directly introducing the external heat source into the oil-water heat exchanger. The two three-way valves are used to control the connectivity of the pipelines in the working state.

4. The cold starting device for an oil-immersed water-cooled transformer according to claim 1, characterized in that: The cold start device directly heats the heat dissipating oil in the main circulation cooling oil circuit through the electric heater provided on the oil-water heat exchanger, and a water stop valve is provided on the main circulation cooling water circuit to control the connectivity of the pipeline in the working state.

5. The cold starting device for an oil-immersed water-cooled transformer according to claim 1, 2 or 4, characterized in that: The electric heater controls heating operation by supplying power to the heater.

6. The cold starting device for an oil-immersed water-cooled transformer according to claim 1 or 2, characterized in that: The heat source input and output pipelines are arranged in parallel with the oil-water heat exchanger.

Images