A valve side ±1100kV converter transformer

Abstract

The present application belongs to the field of transformer manufacturing, and particularly relates to a valve side +1100kV converter transformer. The valve side +1100kV converter transformer comprises a mesh bushing, a neutral point bushing, and a core with multiple core columns arranged in an oil tank, a valve bushing a and a valve bushing b; on each core column, from opposite sides of the core column, a voltage regulating coil, a mesh coil and a valve coil are sequentially arranged; a bias coil is arranged on the lower insulation part of the voltage regulating coil and the lower insulation part of the mesh coil; the outgoing line of the voltage regulating coil is connected with a switch, and the outgoing line of the switch is connected with the neutral point bushing; the mesh coil of each core column is axially led out from the upper outgoing line shaft and connected with the mesh bushing, and the lower outgoing line of the mesh coil is connected with the switch; each valve coil respectively leads out one outgoing line at the upper end part and the lower end part, and the outgoing lines are respectively connected with the valve bushing a and the valve bushing b after being radially led out. The bias coil structure is adopted in the present application, the number of voltage regulating outgoing lines is reduced by half, the problem of local overheating caused by excessive voltage regulating current is solved, and the arrangement of the voltage regulating outgoing lines is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of transformer manufacturing, specifically a valve-side ±1100kV converter transformer. Background Technology

[0002] Previously, the highest valve-side voltage level for DC projects was 800kV. Currently, there are many ±800kV DC transmission projects, including Xiangshang, Hami-Zhengzhou, Xiluodu-Zhexi, Jinbei-Nanjing, Ximeng-Taizhou, and Zhalute-Qingzhou. However, the Changji-Guquan transmission distance is 3284km, which is quite long. The longer the transmission distance, the lower the cost of DC transmission. Increasing the valve-side voltage can significantly reduce transmission losses, saving energy and reducing costs. Therefore, the cost-effectiveness of ±1100kV DC transmission projects is far superior to ±800kV DC projects. Furthermore, the Northwest Power Grid in my country is a 750kV grid. From an energy-saving and cost-reducing perspective, the grid-side voltage of this converter transformer is ±750kV, and the valve-side voltage is ±1100kV. The development of the ±1100kV converter transformer not only fills a gap both domestically and internationally, but also, for ultra-long-distance DC transmission, ±1100kV DC transmission is beneficial for ultra-long-distance transmission.

[0003] Secondly, in existing converter transformers, due to the high end electric field, the cooling oil channels cannot be directly introduced into the coil from the coil end, which will damage the coil end. At the same time, because the capacity of the converter transformer is large and the number of taps of the voltage regulating leads is large, a large current will be generated when the voltage regulating leads are connected, causing local overheating. Moreover, when there are many taps, the internal structure is complex, which is not conducive to the assembly of the converter transformer body. Summary of the Invention

[0004] In view of the fact that there is no converter transformer with ±1100kV valve side in the existing technology, the purpose of this invention is to provide a converter transformer with ±1100kV valve side to address the problems of transmission loss and unreasonable economic efficiency in ultra-long-distance power transmission exceeding 3000km.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A valve-side ±1100KV converter transformer includes: a grid bushing, a neutral point bushing, and an iron core with multiple core columns disposed in an oil tank, valve bushing a and valve bushing b;

[0007] On each core column, starting from the opposite side of the core column, a voltage regulating coil, a grid coil, and a valve coil are arranged in sequence; a bias coil is provided in the insulation part below the voltage regulating coil and the insulation part below the grid coil.

[0008] The lead wire of the voltage regulating coil of each core column is connected to the switch, and the lead wire of the switch is connected to the neutral point bushing on the oil tank.

[0009] The net coil of each core column is axially led out from the upper lead-out spool and connected with the net sleeve pipe on the oil tank, and the lower end of the net coil of each core column is axially led out and connected with the switch.

[0010] Each valve coil respectively leads out a lead-out wire at the upper end and the lower end, and the lead-out wires are respectively connected with the valve sleeve pipe a and the valve sleeve pipe b after being led out radially.

[0011] The voltage regulating coil and the lower part of the net coil of each core column are respectively connected with the switch through the bias coil.

[0012] The switch is a load tap changer.

[0013] The lead-out wire of the valve coil is provided with a lead-out wire insulation at the head.

[0014] After the valve coils of each core column are connected in parallel, the lead-out wire insulation is passed, and then the lead-out wire is led out from the valve side riser through the lead-out device, the riser lead-out device and the valve side riser in sequence and connected with the valve side sleeve pipe.

[0015] The lower part of the valve side riser is provided with a shielding ring at the connection position with the top of the tank cover of the oil tank, so that the electric field distribution of the converter transformer is uniform.

[0016] The lead-out device and the riser lead-out device are coaxially arranged with the valve side riser, and the internal part of the lead-out device and the internal part of the riser lead-out device are both provided with a voltage equalizing ball.

[0017] The cooler group is fixed to the short shaft side of the oil tank through a support, and the cooler group is connected with the oil tank through an oil pipeline, so that the transformer oil enters the oil tank through the cooler group, and then flows into the voltage regulating coil, the net coil and the valve coil through the internal insulation oil guide pipe, and then is led out from the other side of the coil.

[0018] The voltage regulating coil is connected with the switch connection terminal through the voltage regulating lead wire of the switch, so that the switch realizes the connection of the bias coil at the lower part of the voltage regulating coil through the tap selector rotation.

[0019] The number of turns of the bias coil is the same as the tap number of the voltage regulating coil 1, and the tap voltage of the bias coil is twice the voltage of each stage of the voltage regulating coil, so that the number of voltage regulating lead wires is reduced, and when the bias coil is connected in series, at least one voltage regulating tap is increased or reduced.

[0020] The present application has the following beneficial effects and advantages:

[0021] 1. The coil arrangement mode of the converter transformer of the present application adopts the structure of voltage regulating coil - net coil - ±1100kV valve coil in turn from the core, the ±1100kV outgoing line is radially horizontally led out from the upper end and the lower end of the valve coil, the "hand in hand" structure is adopted between each column, and the outgoing line is led to the outside of the column next to the body in the oil tank, then vertically led out through the tank cover, and connected to the ±1100kV valve sleeve terminal through the ±1100kV valve outgoing line device; the valve side coil end is axially led out, which not only ensures the distance of the valve side outgoing line to the ground, but also does not cause the structural damage of the upper insulation parts such as the press plate, and ensures the mechanical strength and short circuit resistance of the press plate. While meeting the performance parameters, the design and operation difficulty of the main insulation structure is reduced, and the safety and reliability of the product is improved.

[0022] 2. The present application adopts the bias coil structure, which reduces the number of voltage regulating leads by half, not only solves the problem of local overheating caused by excessive voltage regulating current, but also facilitates the arrangement of voltage regulating leads. If the subsequent product has too many voltage regulating taps and the transformer capacity is large, the bias coil structure can also be used to avoid this problem.

[0023] 3. The present application develops the main longitudinal insulation structure of the ±1100kV valve coil, and because the end electric field is high, the cooling oil channel cannot be directly led into the coil from the end of the coil, and a cooling structure is developed, which enters the coil from the middle of the valve coil assembly and flows out from the middle of the valve coil assembly.

[0024] 4. The present application effectively solves the problem of more than 3000km DC power transmission, and the voltage upgrade can effectively reduce the loss of DC power transmission, greatly improve the power transmission efficiency, and improve the economic benefit.

[0025] 5. The ±1100kV converter transformer on the valve side of the present application is first developed and designed, which is the highest voltage level and insulation level of the converter transformer in the world at present, and fills the international and domestic technical and manufacturing gap in the field of converter transformer. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the external structure position diagram of the converter transformer of the present application;

[0027] Figure 2 is the internal winding arrangement and internal wiring schematic diagram of the converter transformer of the present application;

[0028] Figure 3 is the internal structure schematic diagram of the converter transformer of the present application;

[0029] Figure 4 is the wiring principle diagram of the converter transformer of the present application;

[0030] Figure 5 is the cooling oil channel structure principle diagram of the present application;

[0031] Figure 6 This is a comparison chart of transmission distance and cost between the present invention and those limited to converter transformers;

[0032] Among them, 1 is the voltage regulating coil, 2 is the grid coil, 3 is the valve coil, 4 is the outgoing insulation, 5 is the outgoing device, 6 is the box cover, 7 is the shielding ring, 8 is the valve side riser seat, 9 is the riser seat outgoing device, 10 is the grid sleeve, 11 is the neutral point sleeve, 12 is the valve side sleeve, 13 is the iron core, 14 is the cooler group, 15 is the oil tank, 16 is the switch, and 17 is the bias coil. Detailed Implementation

[0033] The present invention will now be further described with reference to the accompanying drawings.

[0034] The valve-side ±1100kV converter transformer of this invention is a single-phase on-load tap-changing converter transformer, which is currently the converter transformer with the highest valve-side voltage level. For example... Figure 1 The diagram shows the external structure of the converter transformer of the present invention. The grid bushing 10(A) and the neutral point bushing 11(B) are arranged on the top of the tank cover 6, and the ±1100kV valve bushing a and valve bushing b are arranged on the top of the tank cover 6; the cooler group 14 is arranged on the other side of the short shaft of the oil tank 15.

[0035] like Figure 2 As shown, the present invention discloses a valve-side ±1100kV converter transformer. The converter transformer coil arrangement adopts a structure starting from the core 13, in sequence as voltage regulating coil 1-grid coil 2-±1100kV valve coil 3. The ±1100kV valve coil 3 is radially led out horizontally from the upper lead wire 17 and the lower lead wire 18 of the valve coil, led out to the outside of the side column of the transformer body inside the oil tank 15, and then vertically led out through the ±1100kV output device at the tank cover 6. After being led out, it enters the valve-side riser seat 8, and after passing through the 1100kV valve riser seat internal output device 9, it is installed on the valve sleeve 12. The cooler group 14 is arranged on the short shaft on the other side of the oil tank 15.

[0036] The following is combined Figure 2 Schematic diagram of the internal winding arrangement and wiring of the converter transformer Figure 3 The internal winding arrangement of the converter transformer and the simplified diagram of the ±1100kV valve outlet are explained below:

[0037] The oil tank 15 is equipped with an iron core 13. On each iron core column, starting from the iron core 13, a voltage regulating coil 1, a grid coil 2 and a valve coil 3 are arranged in sequence. A bias coil 17 is placed in the lower insulating part of the voltage regulating coil 1 and the grid coil 2.

[0038] The leads of the voltage regulating coil 1 of each iron core column are connected in parallel and then connected to the switch 16. The leads of the switch 16 are connected to the neutral point bushing 11 on the cover 6 of the oil tank 15.

[0039] The wire mesh coil 2 of each core column is connected to each other by an axial lead-out wire at the upper end, and is connected to the wire mesh sleeve 10 on the cover 6 of the oil tank 15. The axial lead-out wire at the lower end of the wire mesh coil 2 of each core column is connected to the switch 16.

[0040] A lead wire is drawn from the upper end and the lower end of the valve coil 3, and after being drawn radially, it is connected to the valve sleeve a and the valve sleeve b respectively.

[0041] The lower parts of the voltage regulating coil 1 and the mesh coil / 2 of each core column are connected to the switch 16 through the bias coil 17.

[0042] The internal windings of this invention are arranged as follows:

[0043] The ±1100kV converter transformer on the valve side adopts a structure from the inside out: core 13 - voltage regulating coil 1 - grid coil 2 - valve coil 3 - oil tank 15. For example... Figures 2-3 As shown, the voltage regulating coil 1 is located closest to the core 13 on the innermost side, followed by the grid coil 2, and the ±1100kV valve coil 3 is placed on the outermost side. Placing the higher voltage-level ±1100kV valve coil 3 outside the grid coil 2, with radial leads at the end of the valve coil 3, ensures the distance from the valve-side lead to ground without causing structural damage to the upper insulating components such as the pressure plate, thus guaranteeing the mechanical strength and short-circuit withstand capability of the pressure plate. This structure, while meeting performance parameters, reduces the design and operation difficulty of the main insulation structure and improves the safety and reliability of the product.

[0044] The internal wiring of this invention is as follows:

[0045] The grid coil 2 and valve coil 3 between each core column are in parallel. The leads of the same coils are connected together and then led out to the bushing. The lead of the voltage regulating coil 1 is led to the switch 16 and is connected in parallel in the switch 16. The neutral point bushing 11 on one side of the switch 16 is connected, and the other side is connected to the end of the grid coil.

[0046] The wires of the wire coil 2 extend axially from the end, with the first and last ends leading out from the cover 6 and connected to the wire sleeve 10 and the neutral point sleeve 11, respectively.

[0047] like Figure 3 The diagram shows the internal structure of the converter transformer of the present invention. After the valve coils 3 of each main column are connected in parallel, they pass through the outgoing insulation 4 and are led out from the valve side riser 8 through the outgoing device 5 and the riser outgoing device 9 in sequence, and connected to the valve side bushing 12.

[0048] The cable outlet device 5 and the cable outlet device 9 of the riser seat are concentrically arranged with the valve-side riser seat 8; both the cable outlet device 5 and the riser seat 9 are equipped with equalizing balls; the valve-side leads pass through the equalizing balls of the cable outlet device 5 and the riser seat cable outlet device 9 in sequence and are connected to the valve-side sleeve 12. An insulating cable outlet block (4) is provided at the end of the lead wire of the valve coil (3). The cable outlet insulation (4) can both divide the oil gap and fix the lead wire.

[0049] The valve coil 3 is led out horizontally in a radial direction at both ends. It is connected to valve sleeve a and valve sleeve b via upper and lower lead wires. It is led out through the insulated lead wire 4 in the oil tank 15 to the outside of the side column of the device body. Then, it is led out vertically through the top 6 box cover via the lead wire device 5 to the valve side riser seat 8. It is then connected to the valve side sleeve 12 via the riser seat lead wire device 9.

[0050] The cable outlet device 5 and the cable outlet device 9 of the riser seat are coaxially arranged with the riser seat 8 on the valve side; both the cable outlet device 5 and the cable outlet device 9 of the riser seat are equipped with pressure equalization balls.

[0051] To ensure a uniform electric field distribution, a shielding ring 7 is placed at the connection between the box cover 6 and the valve-side riser seat 8. The upper and lower parts of the valve coil 3 both have radial leads. The upper and lower leads of the valve coil 3 enter the valve-side riser seat 8 through the lead-out device 5, and a riser lead-out device 9 is placed at the connection with the valve-side sleeve 12.

[0052] like Figure 5 The diagram shows the oil flow path of the 1100kV valve coil. The cooler assembly 14 is fixed to the short shaft side of the oil tank 15 via a bracket. The cooler assembly 14 is connected to the oil tank 15 via oil pipelines. After the transformer oil enters the oil tank through the cooler assembly 14, it flows into the voltage regulating coil 1, the grid coil 2, and the valve coil 3 respectively through internal insulated oil guide pipes. Because the insulation level at the end of the valve coil 3 is high, if the oil flowed into the coil from the end, it would cause damage. To ensure that the end insulation is not damaged, the oil path is introduced from the corresponding sides of the voltage regulating coil 1, the grid coil 2, and the valve coil 3, guiding the oil flow to the lower middle part beside the voltage regulating coil 1, the grid coil 2, and the valve coil 3, entering the coil, and then exiting from the upper middle part beside the other side of the coil. The internal insulated oil guide pipe has a serpentine bend structure.

[0053] like Figure 4 The diagram shown is a schematic diagram of the converter transformer wiring principle of the present invention.

[0054] Switch 16 is an on-load tap changer. The end of the grid coil 2 and each tap section of the voltage regulating coil 1 are led to switch 16 to realize on-load voltage regulation connection and tap adjustment. The voltage regulating coil 1 is connected to the terminal of switch 16 through the voltage regulating lead of switch 16, so that the bias coil 17 at the lower part of the voltage regulating coil 1 can be connected by rotating switch 16 through the tap selector.

[0055] The bias coil 17 is located within the insulated end ring at the lower part of the voltage regulating coil 1 and the grid coil 2, and is connected to the tap changer 16. After the voltage regulating coil 1 is connected to the corresponding numbered terminal of the switch 16 via the voltage regulating lead, the switch 16 will select whether the bias coil 4 is connected through its own selector. The bias coil 17 has the same number of turns as one tap of the voltage regulating coil 1. The tap voltage of the bias coil 17 is twice the set voltage of each stage of the voltage regulating coil 1 to reduce the number of voltage regulating leads. When the bias coil 17 is connected, it is equivalent to adding or removing at least one voltage regulating tap. When the bias coil 17 is connected, it is equivalent to adding another tap to the voltage regulating coil 1, thereby achieving the function of voltage regulation.

[0056] Both ends of the bias coil 17 are connected to the switch 16. The number of turns of the bias coil is exactly the same as that of one tap of the voltage regulating coil. The tap is adjusted by selecting whether the bias coil is connected using a tap selector. The connection method is as follows: Figure 4 As shown, switch 16 is located at the grid-side neutral point of the converter transformer and is connected to the grid-side neutral point bushing 11. The adjusted tap changer is led out from switch 16 to the neutral point bushing 11.

[0057] In addition, such as Figure 5 The diagram shows the schematic of the cooling oil channel structure of this invention. In conventional converter transformers, the cooling oil enters the coil from the coil end for cooling. However, in this invention, a cooler assembly 14 is installed on the other side of the short shaft of the oil tank 15. The cooler assembly 14 is fixed together by a bracket and connected to the oil tank 14 via oil pipes. Transformer oil enters the oil tank through the cooler 14 and then flows into the entire transformer body through internal insulated oil pipes, flowing into the regulating coil 1, the main coil 2, and the valve coil 3 respectively. Because the electric field at the end of the valve coil 3 is high, to avoid disrupting the electric field structure at the end of the valve coil 3, the oil flow is directed to the lower middle part next to the valve coil 3 after entering the high electric field region. The oil then enters the coil from the lower middle part of the valve coil 3 and exits from the upper middle part next to the valve coil 3. The cooling oil channel has a serpentine, bendable structure.

[0058] Embodiments of the present invention Figure 2 and attached Figure 4 The converter transformer shown has a two-main-column and two-side-column structure; this patent also applies to a three-main-column and two-side-column structure. The coils on the added main columns are also in parallel.

[0059] like Figure 6 The figure shown is a comparison chart of transmission distance and cost between the present invention and that limited to converter transformers;

[0060] When the power transmission distance is farther, the DC power transmission cost is lower, the valve side voltage is raised, the transmission loss can be greatly reduced, the energy is saved and the cost is reduced, so the cost performance of the ±1100kV DC power transmission project is much higher than that of the ±800kV DC project, and the northwest power grid in China is a 750kV power grid, from the point of view of energy saving and cost reduction, the grid side voltage of the converter transformer is ±750kV, and the valve side voltage of the converter transformer of the application is ±1100kV. Moreover, for super-long distance DC power transmission, ±1100kV DC power transmission is beneficial to super-long distance transmission.

Claims

1. A valve-side ±1100kV converter transformer, characterized in that, include: The wire mesh sleeve (10), the neutral point sleeve (11), and the iron core (13) with multiple core columns located in the oil tank (15), valve sleeve a and valve sleeve b; On each core column, starting from the opposite side of the core column, a voltage regulating coil (1), a mesh coil (2), and a valve coil (3) are arranged in sequence; a bias coil (17) is provided in the insulation part at the bottom of the voltage regulating coil (1) and the insulation part at the bottom of the mesh coil (2). The lead wire of the voltage regulating coil (1) of each core column is connected to the switch (16), and the lead wire of the switch (16) is connected to the neutral point bushing (11) on the oil tank (15); The wire coil (2) of each core column is axially led out from the upper lead wire and connected to the wire sleeve (10) on the oil tank (15). The lower end of the wire coil (2) of each core column is axially led out and connected to the switch (16). Each valve coil (3) has a lead wire drawn out from the upper end and the lower end respectively, and after being drawn out radially, it is connected to valve sleeve a and valve sleeve b respectively; The cooler assembly (14) is fixed to the short shaft side of the oil tank (15) by a bracket. The cooler assembly (14) is connected to the oil tank (15) through an oil pipeline. After the transformer oil enters the oil tank through the cooler assembly (14), it flows into the voltage regulating coil (1), the grid coil (2) and the valve coil (3) through the internal insulated oil guide pipe. The oil is introduced from the corresponding side of the voltage regulating coil (1), the grid coil (2) and the valve coil (3), and the oil flow is directed to the lower middle part of the side of the voltage regulating coil (1), the grid coil (2) and the valve coil (3) to enter the coil, and then led out from the upper middle part of the other side of the coil. The internal insulated oil guide pipe has a serpentine bending structure. The voltage regulating coil (1) is connected to the terminal of the switch (16) via the voltage regulating lead of the switch (16), so that the switch (16) can be rotated through the tap selector to realize the connection of the bias coil (17) at the bottom of the voltage regulating coil (1); The number of turns of the bias coil (17) is the same as the number of tap turns of the voltage regulating coil (1). The tap voltage of the bias coil (17) is twice the voltage of each stage of the voltage regulating coil (1) so as to reduce the number of voltage regulating leads. When the bias coil (17) is connected in series, it is equivalent to increasing or decreasing at least one voltage regulating tap.

2. The valve-side ±1100kV converter transformer according to claim 1, characterized in that, The lower part of the voltage regulating coil (1) and the mesh coil (2) of each core column are connected to the switch (16) through the bias coil (17).

3. The valve-side ±1100kV converter transformer according to claim 1, characterized in that, The switch (16) is an on-load tap changer.

4. The valve-side ±1100kV converter transformer according to claim 1, characterized in that, The valve coil (3) has lead wire insulation (4) at the lead wire outlet.

5. A valve-side ±1100kV converter transformer according to claim 1, characterized in that, After the valve coils (3) of each core column are connected in parallel, the outgoing wire insulation (4) is led out from the valve side riser seat (8) through the outgoing wire device (5) and the riser seat outgoing wire device (9) in sequence, and connected to the valve side sleeve (12).

6. A valve-side ±1100kV converter transformer according to claim 5, characterized in that, The lower part of the valve side riser seat (8) is provided with a shielding ring (7) at the connection between the lower part of the valve side riser seat (8) and the top of the tank cover (6) of the oil tank (15) to make the electric field of the converter transformer evenly distributed.

7. A valve-side ±1100kV converter transformer according to claim 5, characterized in that, The outlet device (5) and the riser outlet device (9) are coaxially arranged with the valve-side riser (8); both the outlet device (5) and the riser outlet device (9) are equipped with equalizing balls.

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