A back-to-back hvdc station arrangement

Abstract

The application discloses a back-to-back flexible direct current converter station arrangement type, which comprises two valve halls, an isolation wall arranged between the two valve halls, a direct current wall bushing arranged on the isolation wall, alternating current wall bushings arranged on one side of the hall walls of the valve halls, the alternating current wall bushings being arranged on the same side of the two valve halls, a valve tower arranged in the valve hall, the valve tower comprising six bridge arms, the direct current ends of the bridge arms in the two valve halls being electrically connected through the direct current wall bushing, and the alternating current ends of the bridge arms in the two valve halls being electrically connected with external electrical devices through the alternating current wall bushing. According to the back-to-back flexible direct current converter station arrangement type, the arrangement type is optimized, the land occupation area is reduced, installation and maintenance are facilitated, and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of converter station technology, and in particular to a back-to-back flexible DC converter station layout. Background Technology

[0002] With my country's economic development, the power grid structure has become increasingly complex. The combined operation of AC and DC power grids has led to significant mutual influences, posing a risk of simultaneous commutation failures on multiple DC lines, thus complicating system characteristics. The grid's ability to withstand large-scale blackouts has weakened. Furthermore, the high density of power plants in some areas has resulted in severe short-circuit current exceeding limits, highlighting the contradictions between current limiting control, power supply, and grid reliability, thus affecting the flexibility of the main grid operation. Back-to-back DC projects offer a good solution for optimizing the power grid structure, preserving and maintaining the existing power exchange functions and providing emergency support in case of accidents.

[0003] Back-to-back converter stations, serving as interconnection channels between two power grids, often terminate in densely populated load areas, posing significant challenges to site selection. The large land area required for converter stations, coupled with difficulties in land acquisition and relocation in densely populated areas, has always been a major obstacle to site selection. Furthermore, the routing of connecting power lines must be addressed. To save land, the overall electrical layout needs to be optimized while meeting process requirements. The valve hall and flexible DC-DC transformer area, as the core area of ​​a back-to-back converter station, dictate the overall process flow, land area, and line outgoing direction, affecting all aspects of the station's electrical layout and noise control.

[0004] In traditional converter stations, when the valve hall is arranged in a straight line, the flexible DC-DC transformer areas are located on opposite sides of the valve hall. Flexible DC-DC transformer tracks are required both inside these areas and in the transport channels between them to accommodate the replacement and rerouting needs of spare flexible DC-DC transformers, thus increasing costs. Furthermore, to facilitate the transportation and installation of equipment in the flexible DC-DC transformer areas, transport channels must be considered on both the east and west sides, necessitating an increase in the size of the converter transformer plaza and the land area required. Additionally, the arrangement of flexible DC-DC transformers on both sides results in noise radiating to both sides during operation, necessitating higher noise reduction requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a back-to-back flexible DC converter station layout that optimizes the layout, reduces the floor space required, facilitates installation and maintenance, and lowers costs.

[0006] To achieve the above objectives, the present invention provides a back-to-back flexible DC converter station layout, comprising two valve halls.

[0007] An isolation wall is provided between the two valve chambers, and the isolation wall is equipped with a DC through-wall bushing; an AC through-wall bushing is provided on one side of each valve chamber, and the AC through-wall bushing is located on the same side of both valve chambers; a valve tower is provided in each valve chamber, and the valve tower forms 6 bridge arms; the DC ends of the bridge arms in the two valve chambers are electrically connected through the DC through-wall bushing; the AC ends of the bridge arms in the two valve chambers are electrically connected to external electrical components through the AC through-wall bushing.

[0008] According to some embodiments of the present invention, the bridge arms in the valve hall are arranged in sequence as the upper bridge arm of phase A, the lower bridge arm of phase A, the upper bridge arm of phase B, the lower bridge arm of phase B, the upper bridge arm of phase C, and the lower bridge arm of phase C.

[0009] According to some embodiments of the present invention, the DC terminals of the upper bridge arm of phase A, the upper bridge arm of phase B, and the upper bridge arm of phase C are all electrically connected in parallel via an upper busbar, and the DC terminals of the lower bridge arm of phase A, the lower bridge arm of phase B, and the lower bridge arm of phase C are all electrically connected in parallel via a lower busbar; there are two DC through-wall bushings, and both DC through-wall bushings are disposed on the side of the isolation wall away from the AC through-wall bushings; the two upper busbars are electrically connected through one of the DC through-wall bushings, and the two lower busbars are electrically connected through the other DC through-wall bushing.

[0010] According to some embodiments of the present invention, the upper busbar is disposed above the lower busbar.

[0011] According to some embodiments of the present invention, a DC current measuring device, a DC voltage measuring device, a DC surge arrester, and a DC disconnecting switch are provided between the upper busbar and the DC through-wall bushing, and between the lower busbar and the DC through-wall bushing; the DC current measuring device, the DC voltage measuring device, the DC surge arrester, and the DC disconnecting switch are arranged in a straight line along a direction perpendicular to the isolation wall.

[0012] According to some embodiments of the present invention, a starting circuit region and a flexible DC-DC transformer region are further included, wherein the starting circuit region and the flexible DC-DC transformer region are disposed on the outer side of one end of the valve hall near the AC through-wall bushing; the electrical components of the starting circuit region are electrically connected to the AC terminal of the bridge arm in the valve hall through the AC through-wall bushing; the starting circuit region includes a bridge arm reactor, which is arranged in a straight line; the flexible DC-DC transformer region includes a flexible DC-DC transformer, which is arranged in a straight line.

[0013] According to some embodiments of the present invention, an AC grounding switch, an AC surge arrester, an AC current transformer, and an AC side suspension insulator are sequentially electrically connected between the AC through-wall bushing and the AC end of the bridge arm in the valve hall.

[0014] According to some embodiments of the present invention, the starting circuit area further includes a post insulator, a BR surge arrester, a bypass disconnect switch, a starting resistor, a starting resistor branch current measuring device, a voltage measuring device, a circuit current measuring device, an HGIS, a starting circuit surge arrester, a post insulator, and a busbar, etc.

[0015] According to some embodiments of the present invention, the flexible DC transformer area further includes a valve-side neutral point device, a grid-side neutral point device, and a backup flexible DC transformer; a converter transformer track is provided on the side of the flexible DC transformer away from the starting circuit area; the valve-side neutral point device and the grid-side neutral point device are both disposed between the two flexible DC transformers; the backup flexible DC transformer is disposed at the end of the flexible DC transformer away from the valve-side neutral point device.

[0016] According to some embodiments of the present invention, the system further includes a control building and valve cooling equipment. The control building is located on the outer side of the valve hall away from the AC through-wall bushing. The valve cooling equipment includes an internal valve cooling device and an external valve cooling device. The internal valve cooling device is located inside the control building. The external valve cooling device is located on both sides of the control building and is perpendicular to the isolation wall.

[0017] The present invention discloses a back-to-back flexible DC converter station layout, which, compared with the prior art, has the following advantages:

[0018] The back-to-back flexible DC converter station layout of this invention features two AC through-wall bushings located on the same side of the two valve halls, and a DC through-wall bushing located on the isolation wall between the two valve halls. This creates a U-shaped energy flow pattern in the two back-to-back valve halls, allowing external electrical components connected to the AC ends of the bridge arms in the two valve halls to be arranged in a straight line. The external electrical components connected to the AC ends of the two bridge arms can be arranged in the same direction, resulting in more flexible outgoing wiring and reducing the length of the converter transformer track and the size of the converter transformer plaza. Therefore, the back-to-back flexible DC converter station layout of this invention, through optimized arrangement, reduces the floor space required, facilitates installation and maintenance, and lowers costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the valve hall structure of the back-to-back flexible DC converter station layout according to an embodiment of the present invention;

[0020] Figure 2 yes Figure 1 Enlarged view of point E in the middle;

[0021] Figure 3 yes Figure 1 Enlarged view of point F in the middle;

[0022] Figure 4 This is a schematic diagram of the overall structure of the back-to-back flexible DC converter station layout according to an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram of the start-up circuit area of ​​the back-to-back flexible DC converter station layout according to an embodiment of the present invention;

[0024] Figure 6 yes Figure 5 Enlarged view of point G in the middle;

[0025] Figure 7 This is a schematic diagram of the structure of the flexible DC converter area in the back-to-back flexible DC converter station layout according to an embodiment of the present invention.

[0026] Figure 8 yes Figure 7 Enlarged schematic diagram of point H in the middle.

[0027] Figure label:

[0028] Valve hall 1; Isolation wall 11; DC through-wall bushing 12; AC through-wall bushing 13; Flexible DC valve bridge arm 14; Phase A upper bridge arm 141; Phase A lower bridge arm 142; Phase B upper bridge arm 143; Phase B lower bridge arm 144; Phase C upper bridge arm 145; Phase C lower bridge arm 146; Upper busbar 147; Lower busbar 148; AC grounding switch 15; AC surge arrester 16; AC current transformer 17; AC side suspension insulator 18; DC current measuring device 191; DC voltage measuring device 192; DC surge arrester 193; DC disconnect switch 194;

[0029] Starting circuit area 2; bridge arm reactor 21; post insulator 220; BR surge arrester 221; bypass disconnect switch 222; starting resistor 223; starting resistor branch current measuring device 224; voltage measuring device 225; circuit current measuring device 226; HGIS 227; starting circuit surge arrester 228; post insulator 229; busbar 230;

[0030] Flexible DC-DC transformer area 3; Flexible DC-DC transformer 31; Standby flexible DC-DC transformer 32; Converter transformer track 33; Valve-side neutral point equipment 34; Grid-side neutral point equipment 35;

[0031] Control Building 4. Detailed Implementation

[0032] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0034] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0036] The following is for reference. Figures 1 to 8 The arrangement of a back-to-back flexible DC converter station according to an embodiment of the present invention is described.

[0037] like Figure 1 and 4 As shown, according to an embodiment of the present invention, a back-to-back flexible DC converter station layout is provided, which includes two valve halls 1.

[0038] like Figure 1 As shown, a valve tower is installed in the valve hall 1, and the valve tower consists of 6 bridge arms 14. An isolation wall 11 is installed between the two valve halls 1. The isolation wall 11 is equipped with a DC through-wall bushing 12. The DC ends of the bridge arms 14 in the two valve halls 1 are electrically connected through the DC through-wall bushing 12, thereby isolating the two valve halls 1 in space. When one valve hall 1 is de-energized for maintenance, the other valve hall 1 can be energized as a STATCOM, which can enhance the flexibility of the layout and realize the isolated operation of the two valve halls 1 without interference.

[0039] An AC through-wall bushing 13 is installed on one side wall of each valve hall 1. The AC through-wall bushing 13 is installed on the same side of the two valve halls 1. The AC end of the bridge arm 14 in the two valve halls 1 is electrically connected to the external electrical components through the AC through-wall bushing 13.

[0040] The current from the external electrical device enters the AC terminal of the corresponding bridge arm 14 in the valve hall 1 through one of the AC through-wall bushings 13. The DC terminal of the bridge arm 14 in the valve hall 1 is electrically connected to the DC terminal of the bridge arm 14 in the other valve hall 1 through a DC through-wall bushing 12. The AC terminal of the bridge arm 14 in the other valve hall 1 is electrically connected to the external electrical device on the other side through another AC through-wall bushing 13. Since the AC through-wall bushings 13 are set on the same side of the two valve halls 1, the energy flow direction in the valve hall 1 is arranged in a U-shape. The equipment at the AC terminals of the bridge arms 14 in the two valve halls 1 is set in the same direction, so that the external electrical device does not need to be turned, the outgoing line method is more flexible, the AC terminals of the bridge arms 14 in the two valve halls 1 are outgoing on the same side, and the length of the converter transformer track 33 is reduced, saving materials, reducing the footprint, facilitating installation and maintenance, optimizing the operation and maintenance environment, and reducing costs.

[0041] In the back-to-back flexible DC converter station layout of this invention, two AC through-wall bushings 13 are located on the same side of the two valve halls 1, and a DC through-wall bushing 12 is located on the isolation wall 11 between the two valve halls 1. This results in a U-shaped energy flow pattern in the two valve halls 1, and allows external electrical components connected to the AC terminals of the bridge arms 14 within the two valve halls 1 to be arranged in a straight line. The external electrical components connected to the AC terminals of the bridge arms 14 within the two valve halls 1 can be arranged in the same direction, providing greater flexibility in the outgoing wiring and reducing the length of the converter transformer track 33. Therefore, the back-to-back flexible DC converter station layout of this invention, through optimized arrangement, reduces the floor space required, facilitates installation and maintenance, and lowers costs.

[0042] In some specific embodiments of the present invention, such as Figure 1 As shown, the bridge arm 14 in valve hall 1 consists of the following sequentially arranged phase A upper bridge arm 141, phase A lower bridge arm 142, phase B upper bridge arm 143, phase B lower bridge arm 144, phase C upper bridge arm 145, and phase C lower bridge arm 146. Figure 1 As shown, in this embodiment of the invention, the bridge arm 14 consists of three upper bridge arms and three lower bridge arms. The three upper bridge arms are A-phase upper bridge arm 141, B-phase upper bridge arm 143, and C-phase upper bridge arm 145, and the three lower bridge arms are A-phase lower bridge arm 142, B-phase lower bridge arm 144, and C-phase lower bridge arm 146. Two valve halls 1 are arranged side by side, and an isolation wall 11 is provided between the two valve halls 1. Within one valve hall 1, the A-phase upper bridge arm 141, A-phase lower bridge arm 142, B-phase upper bridge arm 143, B-phase lower bridge arm 144, C-phase upper bridge arm 145, and C-phase lower bridge arm 146 are arranged sequentially. The A-phase upper bridge arm 141, A-phase lower bridge arm 142, B-phase upper bridge arm 143, B-phase lower bridge arm 144, C-phase upper bridge arm 145, and C-phase lower bridge arm 146 are arranged parallel to the isolation wall 11, thereby helping to reduce the footprint.

[0043] In some specific embodiments of the present invention, the DC ends of the upper bridge arm 141 of phase A, the upper bridge arm 143 of phase B, and the upper bridge arm 145 of phase C are all connected in parallel via the upper busbar 147, and the DC ends of the lower bridge arm 142 of phase A, the lower bridge arm 144 of phase B, and the lower bridge arm 146 of phase C are all connected in parallel via the lower busbar 148. There are two DC wall bushings 12, and both DC wall bushings 12 are located on the side of the isolation wall 11 away from the AC wall bushing 13.

[0044] The two upper busbars 147 are electrically connected through one of the DC through-wall bushings 12, and the two lower busbars 148 are electrically connected through the other DC through-wall bushing 12. Furthermore, the upper busbars 147 are suspended, and the upper bridge arms 141 (phase A), 143 (phase B), and 145 (phase C) are connected in a high-in, high-out configuration. The lower busbars 148 are supported, with the upper busbars 147 positioned above them. The lower bridge arms 142 (phase A), 144 (phase B), and 146 (phase C) are connected in a high-in, low-out configuration, which helps to further reduce the footprint.

[0045] Furthermore, each valve hall 1 has six AC through-wall bushings 13, and each valve tower's bridge arm 14 AC terminal corresponds to one AC through-wall bushing 13, thus ensuring smooth valve tower operation and simplifying valve hall 1 wiring.

[0046] In some specific embodiments of the present invention, such as Figure 3 As shown, DC current measuring device 191, DC voltage measuring device 192, DC surge arrester 193, and DC disconnect switch 194 are installed between the upper busbar 147 and the lower busbar 148 and the DC through-wall bushing 12. The DC current measuring device 191, DC voltage measuring device 192, DC surge arrester 193, and DC disconnect switch 194 are arranged in a straight line along the direction perpendicular to the isolation wall 11, thereby optimizing the layout and reducing the floor space.

[0047] In some specific embodiments of the present invention, such as Figure 4As shown, the back-to-back flexible DC converter station of this embodiment of the invention is provided with a start-up circuit area 2 and a flexible DC transformer area 3. The start-up circuit area 2 and the flexible DC transformer area 3 are located on the outer side of the valve hall 1 near the AC through-wall bushing 13, that is, the start-up circuit area 2 and the flexible DC transformer area 3 are located on the same side of the two valve halls 1, and the start-up circuit area 2 and the flexible DC transformer area 3 are connected by a pipe bus. The electrical components of the start-up circuit area 2 are electrically connected to the AC end of the bridge arm 14 in the valve hall 1 through the AC through-wall bushing 13. The start-up circuit area 2 includes a bridge arm reactor 21, which is arranged in a straight line. The flexible DC transformer area 3 includes a flexible DC transformer 31, which is also arranged in a straight line, thereby optimizing the layout and making the flexible DC transformers 31 in both flexible DC transformer areas 3 oriented in the same direction. The replacement of the flexible DC transformer 31 does not require reversing, reducing the difficulty of replacement, saving the length of the converter transformer track 33, saving materials, and reducing costs. The bridge arm reactor 21 and the AC through-wall bushing 13 are located on the same side of the valve hall 1, which can share the maintenance passage and make installation and maintenance more convenient.

[0048] Furthermore, the AC through-wall bushing 13 is set on the south side of the valve hall 1, so that the flexible DC-DC converter area 3 is set on the south side of the valve hall 1. The valve halls 1 on both sides are arranged in a straight line, forming a natural barrier, which helps to reduce the noise of the flexible DC-DC converter area 3.

[0049] In some specific embodiments of the present invention, such as Figure 2 As shown, an AC grounding switch 15, an AC surge arrester 16, an AC current transformer 17, and an AC side suspension insulator 18 are sequentially electrically connected between the AC through-wall bushing 13 and the AC end of the bridge arm 14 in the valve hall 1, thereby optimizing the layout and adopting a DC-side busbar, eliminating the phase-adjusting busbar at the AC end of the bridge arm 14 in the valve hall 1. Figure 1 As shown, the AC current transformer 17 and the AC side suspension insulator 18 are arranged in a straight line along the direction perpendicular to the isolation wall 11. The AC grounding switch 15 and the AC surge arrester 16 are arranged in a straight line along the direction perpendicular to the isolation wall 11. The space between the AC grounding switch 15 and the AC surge arrester and the bridge arm 14 inside the valve hall 1 can be used to arrange the maintenance passage of the lifting platform vehicle, thus optimizing the layout.

[0050] In some specific embodiments of the present invention, such as Figure 5 and 6As shown, the starting circuit area 2 includes a post insulator 220, a BR surge arrester 221, a bypass disconnect switch 222, a starting resistor 223, a starting resistor branch current measuring device 224, a voltage measuring device 225, a circuit current measuring device 226, an HGIS 227, a starting circuit surge arrester 228, a post insulator 229, and a busbar 230. The bypass disconnect switch 222 and the starting resistor 223 are located on the side of the bridge arm reactor 21 facing away from the valve hall 1. The post insulator 220, BR surge arrester 221, bypass disconnect switch 222, starting resistor branch current measuring device 224, voltage measuring device 225, circuit current measuring device 226, and HGIS... 227, 228, 229, and 230 of the starting circuit surge arrester, post insulator, and busbar are set on the other side of the bypass disconnect switch 222 and the starting resistor 223, and are arranged in sequence according to the electrical wiring requirements. The starting circuit area 2 adopts an outdoor supported busbar arrangement. By optimizing the equipment layout, the square layout of the site is realized, and the site space is used reasonably.

[0051] It is understandable that the bridge arm reactor 21 can be an outdoor dry-type air-core reactor. The bridge arm reactor 21 is arranged at a high position and is surrounded by a fence. The bridge arm reactor 21 is connected to the AC through-wall bushing 13 through the cross-circuit bus. The bridge arm reactor 21 and the AC through-wall bushing 13 are arranged in a one-to-one correspondence, thereby optimizing the layout and making the arrangement more flexible.

[0052] In some specific embodiments of the present invention, such as Figure 7 and 8 As shown, the flexible DC transformer area 3 includes a valve-side neutral point device 34 and a grid-side neutral point device 35. The valve-side neutral point device 34 and the grid-side neutral point device 35 are located on the open ground in the middle of the standby flexible DC transformer 32 and are connected by flexible wires. At the same time, the flexible DC transformer area 3 adopts a single-phase double-winding transformer for outdoor layout, which optimizes the layout and reduces the footprint.

[0053] Furthermore, a spare flexible DC transformer 32 is installed on the side of the flexible DC transformer 31 away from the isolation wall 11. That is, the 12 flexible DC transformers 31 are integrated into one transformer, and the spare flexible DC transformer 32 is located at any end of the longer side of the integrated transformer. This allows the flexible DC transformers 31 and the spare flexible DC transformer 32 in the two flexible DC transformer areas 3 to be arranged in a straight line, and the two flexible DC transformers 31 are placed in the same direction. When the spare flexible DC transformer 32 is called in the two flexible DC transformer areas 3, the spare flexible DC transformer 32 does not need to be rotated for replacement. A converter transformer track 33 is installed on the side of the flexible DC transformer 31 away from the starting circuit area 2. The valve-side neutral point equipment and the grid-side neutral point equipment are both located between the two flexible DC transformers 31. The flexible DC transformer pressure and the spare flexible DC transformer 32 can share the converter transformer track 33, which greatly saves the length of the converter transformer track 33 and reduces the cost and floor space.

[0054] In some specific embodiments of the present invention, such as Figure 4 As shown, it also includes a control building 4 and valve cooling equipment. The control building 4 is located on the outer side of the valve hall 1, away from the AC through-wall bushing 13. The control building 4 is close to the two valve halls 1 and arranged in a straight line, making the control of the valve hall 1 relatively centralized, which is convenient for operation and inspection. The valve cooling equipment includes internal valve cooling equipment and external valve cooling equipment; the internal valve cooling equipment is located inside the control building 4, and the external valve cooling equipment is located on both sides of the control building 4. The external valve cooling equipment is arranged perpendicular to the isolation wall 11, thereby optimizing the layout and reducing the footprint. Furthermore, the flexible DC-DC transformer areas 3 are all located on the south side of the valve hall 1, and the control building 4 and valve cooling equipment are concentrated on the north side of the valve hall 1, which helps to reduce the size of the valve hall 1.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A back-to-back flexible DC converter station layout, comprising two valve halls, characterized in that, include: An isolation wall is provided between the two valve chambers, and the isolation wall is equipped with a DC through-wall bushing; an AC through-wall bushing is provided on one side of each valve chamber, and the AC through-wall bushing is located on the same side of both valve chambers; a valve tower is provided inside each valve chamber, and the valve tower consists of 6 bridge arms; the DC ends of the bridge arms in the two valve chambers are electrically connected through the DC through-wall bushing; the AC ends of the bridge arms in the two valve chambers are electrically connected to external electrical components through the AC through-wall bushing. The bridge arms within the valve hall are arranged sequentially as follows: Phase A upper bridge arm, Phase A lower bridge arm, Phase B upper bridge arm, Phase B lower bridge arm, Phase C upper bridge arm, and Phase C lower bridge arm. The DC terminals of the Phase A upper bridge arm, Phase B upper bridge arm, and Phase C upper bridge arm are all electrically connected in parallel via an upper busbar. The DC terminals of the Phase A lower bridge arm, Phase B lower bridge arm, and Phase C lower bridge arm are all electrically connected in parallel via a lower busbar. There are two DC through-wall bushings, both of which are located on the side of the isolation wall furthest from the AC through-wall bushings. The two upper busbars are electrically connected through one of the DC through-wall bushings, and the two lower busbars are electrically connected through the other DC through-wall bushing. The upper busbars are located above the lower busbars. A DC current measuring device, a DC voltage measuring device, a DC surge arrester, and a DC disconnecting switch are provided between the upper busbars and the DC through-wall bushings, as well as between the lower busbars and the DC through-wall bushings. The DC current measuring device, the DC voltage measuring device, the DC surge arrester, and the DC disconnecting switch are arranged in a straight line along a direction perpendicular to the isolation wall.

2. The back-to-back flexible DC converter station layout according to claim 1, characterized in that, It also includes a start-up circuit area and a flexible DC-DC transformer area, which are located on the outer side of the valve hall near the AC through-wall bushing. The electrical components in the start-up circuit area are electrically connected to the AC terminal of the bridge arm in the valve hall through the AC through-wall bushing. The start-up circuit area includes a bridge arm reactor, which is arranged in a straight line. The flexible DC-DC transformer area includes a flexible DC-DC transformer, which is arranged in a straight line.

3. The back-to-back flexible DC converter station layout according to claim 2, characterized in that, The AC through-wall bushing is sequentially electrically connected to the AC end of the bridge arm in the valve hall by an AC grounding switch, an AC surge arrester, an AC current transformer, and an AC side suspension insulator.

4. The back-to-back flexible DC converter station layout according to claim 2, characterized in that, The starting circuit area also includes post insulators, BR surge arresters, bypass disconnect switches, starting resistors, starting resistor branch current measuring devices, voltage measuring devices, circuit current measuring devices, HGIS, starting circuit surge arresters, post insulators, and busbars.

5. The back-to-back flexible DC converter station layout according to claim 2, characterized in that, The flexible DC-DC transformer area also includes a valve-side neutral point device, a grid-side neutral point device, and a backup flexible DC-DC transformer; a converter transformer track is provided on the side of the flexible DC-DC transformer away from the starting circuit area; the valve-side neutral point device and the grid-side neutral point device are both located between the two flexible DC-DC transformers; the backup flexible DC-DC transformer is located at the end of the flexible DC-DC transformer away from the valve-side neutral point device.

6. The back-to-back flexible DC converter station layout according to claim 1, characterized in that, It also includes a control building and valve cooling equipment. The control building is located on the outer side of the valve hall away from the AC through-wall bushing. The valve cooling equipment includes internal valve cooling equipment and external valve cooling equipment. The internal valve cooling equipment is located inside the control building. The external valve cooling equipment is located on both sides of the control building and is perpendicular to the isolation wall.

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