Vacuum oiling method and device for valve bushing transport cylinder of extra-high voltage converter transformer
By designing a vacuum passage structure and an oil injection device, a vacuum is drawn during the oil injection process to isolate the capacitor core from the outside air, thus solving the problem of moisture and deterioration of the bushing insulation and achieving better insulation protection and equipment stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG POWER EQUIP CO LTD
- Filing Date
- 2022-01-20
- Publication Date
- 2026-05-19
AI Technical Summary
Existing technology cannot effectively protect the capacitor core of the valve bushing of the ±800kV UHV converter transformer during the oil injection process, resulting in insulation moisture and deterioration, which affects the safe and stable operation of the equipment.
A vacuum passage structure is designed, including a three-way pipe and an oil filling pipe. By drawing a vacuum during the oil filling process, the capacitor core is isolated from the outside air, ensuring a vacuum oil filling environment and reducing the contact time between the capacitor core and the outside air.
It effectively prevents the capacitor core insulation from being contaminated and damp, improves insulation performance, prevents increased dielectric loss and overheating, and ensures safe and stable operation of the equipment.
Smart Images
Figure CN114446602B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ultra-high voltage converter transformer technology, specifically relating to a method and apparatus for vacuum oil injection into the valve bushing transport cylinder of a ±800kV ultra-high voltage converter transformer. Background Technology
[0002] The ±800kV UHV converter transformer bushing is a key piece of equipment in UHVDC power transmission and transformation projects. This type of bushing is an oil-paper capacitor bushing, with the main insulation being a capacitor core. It is made of oil-impregnated cable paper and aluminum foil, which are interleaved and pressurized on a central conductive rod to form many concentric capacitors centered on the conductive rod, so that the electric field distribution at the tail of the bushing is uniform.
[0003] During the operation of ±800kV converter transformers, bushings not only withstand long-term AC and DC operating voltages, but also lightning overvoltages and transient operational overvoltages. The electric field at the bushing tail is highly concentrated, making it prone to flashover or breakdown discharge in the oil. Therefore, the insulation performance of the bushings is extremely important. To prevent the bushing capacitor cores from being contaminated or damp, the bottom capacitor cores are placed in a transport cylinder provided by the bushing manufacturer and filled with transformer oil during transportation and storage.
[0004] like Figure 1 The diagram shows a schematic of the existing oil filling structure for the valve bushing transport cylinder of an ultra-high voltage converter transformer. When filling the transport cylinder 1 with oil, the cover 2 is removed, and the oil filling pipeline is inserted into the transport cylinder 1. With this oil filling structure, outside air is connected to the transport cylinder 1 during the filling process. While outside air enters the transport cylinder 1 and comes into contact with the capacitor core, ensuring no air remains inside the transport cylinder 1 after filling, the insulating surface at the bottom of the capacitor core absorbs moisture from the air during the filling process. Tiny impurities in the air also easily adhere to the insulating surface. Therefore, this oil filling structure cannot effectively protect the capacitor core, easily causing insulation dampness and deterioration, leading to increased dielectric loss, severe overheating, and accelerated insulation aging, which is detrimental to the safe and stable operation of the converter transformer. Summary of the Invention
[0005] To address the aforementioned technical problems and effectively protect the capacitor core at the bushing tail, this invention provides a method and apparatus for vacuum oil injection into the transport cylinder of a ±800kV UHV converter transformer valve bushing. The vacuum oil injection method and apparatus provide a vacuum oil injection environment, isolating the capacitor core from external air during the oil injection process. The technical solution adopted by this invention is as follows:
[0006] A method for vacuum oil injection into the transport cylinder of an ultra-high voltage converter transformer valve bushing involves designing a vacuum passage structure. The vacuum chamber of this structure includes three ports: a lower port connects to the oil injection port of the transport cylinder; an upper port connects to the oil injection pipeline for injecting oil into the transport cylinder; and a side port connects to a vacuum pumping device for pre-vacuuming and vacuuming during the oil injection process. Using this method, vacuuming is performed immediately after the capacitor core is placed into the transport cylinder, and simultaneously during the oil injection process, significantly reducing the contact time between the capacitor core and external air.
[0007] A device for vacuum oil injection of a transport cylinder for a valve bushing of an ultra-high voltage converter transformer, employing the aforementioned method for vacuum oil injection of a transport cylinder for a valve bushing of an ultra-high voltage converter transformer, includes: a three-way pipe structure and an oil injection pipe structure. The oil injection pipe structure includes: an integrally formed oil injection pipe connector and an oil injection pipe body. The diameter of the oil injection pipe connector is larger than the diameter of the oil injection pipe body, and the oil injection pipe connector mates with the upper opening of the three-way pipe structure. The lower side of the oil injection pipe connector is sealed and welded to the upper side of the upper opening of the three-way pipe structure. The lower end of the oil injection pipe body extends out of the lower opening of the three-way pipe structure. The outer diameter of the oil injection pipe body is smaller than the inner diameter of the upper and lower openings of the three-way pipe structure. The side opening of the three-way pipe structure is connected to a vacuum pumping device, the lower opening of the three-way pipe structure is connected to the transport cylinder, and the upper end of the oil injection pipe connector is connected to an oil injection pipeline. An air deflection groove is provided on the inner side of the middle section of the three-way pipe structure.
[0008] The beneficial effects of this invention are:
[0009] This invention achieves vacuum oil filling of the transport cylinder by using a three-way pipe structure to simultaneously inject oil and create a vacuum, thus providing better protection for the capacitor core.
[0010] This device has a simple structure and is easy to operate. It effectively protects the insulation at the bottom of the sleeve and prevents the insulation from being contaminated or damp.
[0011] The oil injection pipe extends a certain length beyond the tee structure. This design prevents the transformer oil injected into the transport cylinder from being extracted when vacuuming and oil injection are carried out simultaneously. Attached Figure Description
[0012] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some specific embodiments of the present invention. For those skilled in the art, other drawings falling within the scope of protection of this application can be obtained based on these drawings without any creative effort.
[0013] Figure 1 A schematic diagram of the existing oil filling structure for the valve bushing transport cylinder of an ultra-high voltage converter transformer;
[0014] Figure 2 This is a cross-sectional view of the vacuum oil injection device according to an embodiment of the present invention;
[0015] Figure 3 This is a cross-sectional view of the oil injection pipe structure according to an embodiment of the present invention;
[0016] Figure 4 This is a cross-sectional view of the tee pipe structure according to an embodiment of the present invention;
[0017] In the diagram, 1 is the transport cylinder, 2 is the cover, 3 is the three-way pipe structure, 4 is the oil injection pipe structure, 5 is the oil injection pipe connector, 6 is the oil injection pipe body, 7 is the right-angle groove, 8 is the stepped connecting groove, and 9 is the air steering groove. Detailed Implementation
[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0019] A method for vacuum oil injection into the transport cylinder of a UHV converter transformer valve bushing includes a vacuum passage structure. The vacuum cavity of this structure comprises three ports: a lower port connected to the oil injection port of the transport cylinder; an upper port connected to an oil injection pipeline for injecting oil into the transport cylinder; and a side port connected to a vacuum pumping device for pre-vacuuming and vacuuming during the oil injection process. An air deflector is incorporated at the corner of the vacuum passage structure to increase the cross-sectional area for gas flow at the corner, reduce gas flow resistance, and improve vacuuming efficiency.
[0020] like Figure 2 The figure shown is a cross-sectional view of the vacuum oil injection device according to an embodiment of the present invention; the arrows in the figure indicate the gas flow direction before oil injection and during vacuuming. A vacuum oil injection device for a valve bushing transport cylinder of an ultra-high voltage converter transformer includes: a three-way pipe structure 3 and an oil injection pipe structure 4, wherein the three-way pipe structure 3 and the oil injection pipe structure 4 are made of stainless steel, which can meet the transformer purification requirements.
[0021] like Figure 3The diagram shows a cross-sectional view of the oil injection pipe structure according to an embodiment of the present invention. The oil injection pipe structure 4 includes: an integrally formed oil injection pipe connector 5 and an oil injection pipe body 6. The diameter of the oil injection pipe connector 5 is larger than the diameter of the oil injection pipe body 6. The oil injection pipe connector 5 mates with the upper opening of the tee pipe structure 3. The tee pipe structure 3 and the oil injection pipe structure 4 are welded together. The lower side of the oil injection pipe connector 5 is sealed and welded to the upper side of the upper opening of the tee pipe structure 3. The lower end of the oil injection pipe body 6 extends out of the lower opening of the tee pipe structure 3. The outer diameter of the oil injection pipe body 6 is smaller than the inner diameter of the upper and lower openings of the tee pipe structure 3. The side opening of the tee pipe structure 3 connects to a vacuum pumping device; specifically, the side thread of the side opening of the tee pipe structure 3 connects to a vacuum pumping pipeline. The lower opening of the tee pipe structure 3 connects to a transport cylinder 1; specifically, the thread of the lower opening of the tee pipe structure 3 connects to the oil injection port of the transport cylinder 1. The upper end of the oil injection pipe connector 5 is connected to the oil injection pipeline, which is equipped with an oil injection control valve. The cavity formed by the outer circumference of the oil injection pipe body 6, the inner circumference of the tee structure 3, and the inner circumference of the side opening of the tee structure 3 constitutes a sealed vacuum passage, and the sealed cavity structure creates a vacuum environment. Furthermore, the upper end of the oil injection pipe connector 5 has a pipe thread for quick and convenient connection to the oil injection pipeline.
[0022] like Figure 4 The figure shows a cross-sectional view of the three-way pipe structure according to an embodiment of the present invention. A 2mm right-angled groove 7 is provided at the edge of the upper opening of the three-way pipe structure 3. The right-angled groove 7 is tightly fitted and sealed with the lower end of the oil injection pipe connector 5. The right-angled groove 7 is used for precise positioning when welding the upper opening of the three-way pipe structure 3 to the oil injection pipe connector 5, improving the concentricity between the two, and preventing weld slag and other impurities from contaminating the transformer oil in the transport cylinder 1 during oil injection. A stepped connecting groove 8 is provided at the lower opening end of the three-way pipe structure 3. The stepped connecting groove 8 is used for quick and convenient connection to the transport cylinder 1, and the stepped connecting groove 8 can improve the versatility of the vacuum oil injection device. An air-directing groove 9 is provided on the inner side of the middle section of the three-way pipe structure 3. The depth of the air-directing groove 9 is 4mm and the radius is 22mm. If the air-directing groove 9 is not provided, the air flow turning angle is 90°. When the gas reaches the corner, the flow rate decreases, the flow resistance increases, and turbulence is easily formed. The kinetic energy of the air flowing in the pipe joint is converted into the energy of turbulence, causing energy dissipation. The outflow of air decreases accordingly, and the vacuuming efficiency decreases. After providing the air-directing groove 9, the specific path of gas discharge during vacuuming is as follows: Figure 2 As shown, increasing the cross-sectional area for gas flow at the corner reduces the resistance to gas flow at this point, thus avoiding the aforementioned problems and improving the efficiency of vacuuming.
[0023] The working principle of this invention is as follows:
[0024] 1. The upper end of the oil injection pipe connector 5 is connected to the oil injection pipe, the lower port of the three-way pipe structure 3 is connected to the transport cylinder 1, and the side port of the three-way pipe structure 3 is connected to the vacuum pumping device, forming a closed vacuum pumping passage.
[0025] 2. After the capacitor core is placed into transport cylinder 1, the vacuum device is turned on to evacuate transport cylinder 1. When the vacuum degree inside transport cylinder 1 reaches 100 Pa, it is maintained for 4 hours to facilitate the removal of moisture adsorbed on the surface of the sleeve capacitor core.
[0026] 3. Open the oil injection pipeline control valve to inject transformer oil into the transport cylinder 1. During oil injection, a vacuum is continuously drawn. The gas in the transport cylinder 1 is discharged through the three-way pipe structure 3. This not only discharges the gas in time, but also prevents the capacitor core from contacting the outside air, effectively protecting the insulation of the capacitor core at the bottom of the bushing and preventing the capacitor core insulation from being contaminated and damp.
[0027] 4. After the oil filling is completed, remove the vacuum oil filling device and install the cover 2.
[0028] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.
Claims
1. A method for vacuum oil injection into the transport cylinder of a UHV converter transformer valve bushing, characterized in that, Design a vacuum passage structure. The vacuum cavity of the vacuum passage structure includes three ports: the lower port is connected to the oil filling port of the transport cylinder, the upper port is connected to the oil filling pipeline for filling oil into the transport cylinder of the UHV converter transformer valve bushing, and the side port is connected to a vacuum pumping device for pre-vacuuming and vacuuming during the oil filling process. An air deflection structure is set at the corner of the vacuum passage structure to increase the cross-sectional area of gas flow at the corner. The device for vacuum oil injection of the transport cylinder of the valve bushing of the UHV converter transformer using the above method includes: a three-way pipe structure (3) and an oil injection pipe structure (4). The oil injection pipe structure (4) includes: an integrally formed oil injection pipe connector (5) and an oil injection pipe body (6). The diameter of the oil injection pipe connector (5) is larger than the diameter of the oil injection pipe body (6). The oil injection pipe connector (5) is matched with the upper opening of the three-way pipe structure (3). The lower side of the oil injection pipe connector (5) is sealed and welded to the upper side of the upper opening of the three-way pipe structure (3). The lower end of the oil injection pipe body (6) extends out of the lower opening of the three-way pipe structure (3). The outer diameter of the oil pipe body (6) is smaller than the inner diameter of the upper and lower openings of the three-way pipe structure (3). The side opening of the three-way pipe structure (3) is connected to the vacuum pumping device, and the lower opening of the three-way pipe structure (3) is connected to the transport cylinder (1). The upper end of the oil injection pipe connector (5) is connected to the oil injection pipeline. An air turning groove (9) is provided on the inner side of the middle part of the three-way pipe structure (3). A right-angle groove (7) is provided at the edge of the upper opening of the three-way pipe structure (3). The right-angle groove (7) is tightly fitted and sealed with the lower end of the oil injection pipe connector (5). A stepped connecting groove (8) is provided at the lower opening end of the three-way pipe structure (3).
2. The method for vacuum oil injection into the transport cylinder of the UHV converter transformer valve bushing according to claim 1, characterized in that, The three-way pipe structure (3) and the oil injection pipe structure (4) are made of stainless steel.
3. The method for vacuum oil injection into the transport cylinder of the UHV converter transformer valve bushing according to claim 1, characterized in that, The side thread of the three-way pipe structure (3) is connected to the vacuum pipeline.
4. The method for vacuum oil injection into the transport cylinder of the UHV converter transformer valve bushing according to claim 1, characterized in that, The upper end of the oil injection pipe connector (5) has a pipe thread.