A high-voltage direct-current converter station active voltage regulation topology and system

Abstract

The application discloses a high-voltage direct-current converter station active voltage regulation topology structure and system, comprising: using a power taking transformer to provide power for active voltage regulators of a voltage level and a higher voltage level, so that the whole topology structure is compact, the number of power taking transformers and three-winding converter transformers in the direct-current converter station is greatly reduced, the floor area is reduced, the design difficulty, volume and cost of high-end converter transformers are reduced, and the technical economy of the active voltage regulator in the application of the extra-high voltage converter station is improved.

Description

Technical Field

[0001] This invention relates to the field of high voltage direct current transmission technology, specifically to an active voltage regulation topology and system for a high voltage direct current converter station. Background Technology

[0002] In high-voltage direct current (HVDC) transmission systems, the on-load tap changer of the converter transformer is used to adjust the valve-side voltage to ensure the safety and economy of the DC system operation. Limited by the slow response speed, lack of continuous adjustability, and unsuitability for repeated operation of existing mechanical tap changers, an amplitude modulation (AM) voltage regulation technology based on power electronics has been explored. This active voltage regulation technology utilizes the rapid response characteristics of power electronics to achieve fast response, continuous adjustability, and unlimited operation. Furthermore, it can quickly support the commutation voltage of the converter valve when the system voltage is low, solving the inherent problem of commutation failure in DC transmission systems and significantly improving the operational reliability of the DC system.

[0003] Active voltage regulation technology uses a voltage regulator converter with adjustable amplitude and phase to change the voltage across the grid winding of the converter transformer between the grid-side winding end and the neutral point or ground. This changes the voltage across the grid-side winding to regulate the valve-side voltage, thus meeting the needs of safe and economical operation of DC systems and completely eliminating mechanical voltage regulator switches.

[0004] The energy harvesting transformer provides energy to the converter modules in a voltage regulating converter, while also electrically isolating the converter from the converter transformer. To output a voltage with low harmonic content and high voltage, the converter module is generally composed of multiple back-to-back converter submodules cascaded together. The energy harvesting transformer consists of a primary winding and multiple secondary windings, which can provide energy to the multiple back-to-back converter submodules respectively. In the existing technology, each converter transformer needs to be equipped with an energy harvesting transformer, and each converter transformer needs to include a grid-side winding, a valve-side winding, and an energy harvesting winding. The addition of independent energy harvesting windings to the converter transformer leads to increased design and manufacturing difficulties, larger footprint, and transportation difficulties. It also results in a large number of energy harvesting transformers, high cost, large footprint, and low economic efficiency. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the existing active voltage regulation topology of high voltage DC converter stations, which has a large footprint and low economic efficiency, and thus provide an active voltage regulation topology and system for high voltage DC converter stations.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide an active voltage regulation topology for a high-voltage direct current converter station, comprising: a two-winding converter transformer, a three-winding converter transformer, an energy extraction transformer, an active voltage regulator, a first converter, and a second converter. The primary winding of the two-winding converter transformer has a first end connected to an AC bus, and the second end of its primary winding is connected to the first end of the inverter side of the active voltage regulator. The secondary winding of the two-winding converter transformer is correspondingly connected to the AC side of the first converter. The primary winding of the three-winding converter transformer has a first end connected to an AC bus, and the second end of its primary winding is connected to the inverter side of the active voltage regulator. The first terminal of the three-winding converter transformer is connected to the AC side of the second converter, and the second secondary terminal of the three-winding converter transformer is connected to the two ends of the primary side of the energy extraction transformer. The second terminal of the inverter side of the active voltage regulator is connected to the neutral point or grounded, and the rectifier side of the active voltage regulator is connected to the secondary side of the energy extraction transformer. The DC side of the first converter and the DC side of the second converter are connected in series to output the supply voltage. The energy extraction transformer draws energy from the three-winding converter transformer and supplies energy to the active voltage regulator. By controlling the operating state of the active voltage regulator, the output voltage of the two-winding converter transformer and the three-winding converter transformer is controlled.

[0008] In one embodiment, the dual-winding converter transformer includes: a first grid-side winding and a first valve-side winding, wherein a first end of the first grid-side winding is connected to an AC bus, and a second end of the first grid-side winding is connected to a first end of the inverter side of an active voltage regulator; the two ends of the first valve-side winding are correspondingly connected to the AC side of the first converter.

[0009] In one embodiment, the three-winding converter transformer includes: a second grid-side winding, a second valve-side winding, and an energy extraction winding, wherein the first end of the second grid-side winding is connected to the AC bus, the second end of the primary side of the second grid-side winding is connected to the first end of the inverter side of an active voltage regulator; the two ends of the second valve-side winding are correspondingly connected to the AC side of the second converter; and the two ends of the energy extraction winding are correspondingly connected to the two ends of the primary side of the energy extraction transformer.

[0010] In one embodiment, the active voltage regulator includes: a plurality of first anti-parallel thyristor modules cascaded together and a plurality of back-to-back converter submodules cascaded together, wherein the inverter side of each converter submodule is connected in parallel with a first anti-parallel thyristor module; the first terminal of the cascaded inverter side of each back-to-back converter submodule is connected to the second terminal of the primary side of a three-winding converter transformer; the second terminal of the cascaded inverter side of each back-to-back converter submodule is connected to the neutral point or grounded; and the rectifier side of each back-to-back converter submodule is correspondingly connected to the secondary side of a power extraction transformer.

[0011] In one embodiment, the back-to-back converter submodule includes: a rectifier module, a DC capacitor, and an inverter module. The AC side of the rectifier module is connected to the secondary side of the energy harvesting transformer, and the DC side of the rectifier module is connected in parallel with the DC capacitor. The DC side of the inverter module is connected to the DC side of the rectifier module, and a first anti-parallel thyristor module is connected in parallel on the AC side of the inverter module. The AC side of the inverter module is also cascaded with the AC side of the inverter module of the adjacent back-to-back converter submodule.

[0012] In one embodiment, the active voltage regulator further includes a bypass system, wherein the bypass system is connected in parallel to both ends of the inverter side of each back-to-back converter submodule after cascading; the bypass system is used to bypass the active voltage regulator.

[0013] In one embodiment, the bypass system includes a mechanical switch and a second anti-parallel thyristor module, wherein the mechanical switch and the second anti-parallel thyristor module are connected in parallel.

[0014] In one embodiment, the energy extraction transformer includes a primary winding and a plurality of secondary windings, wherein the primary winding is connected to both ends of the second secondary side of the three-winding converter transformer; each secondary winding is connected to both ends of the rectifier side of a back-to-back converter submodule of an active voltage regulator.

[0015] Secondly, embodiments of the present invention provide an active voltage regulation system for a high-voltage direct current converter station, comprising: a plurality of active voltage regulation topologies for a high-voltage direct current converter station as described in the first aspect, wherein the input terminal of each active voltage regulation topology is connected to an AC bus, and the output terminals of each active voltage regulation topology are connected in series.

[0016] The technical solution of this invention has the following advantages:

[0017] The active voltage regulation topology and system for high-voltage DC converter stations provided by this invention utilizes energy harvesting transformers to provide energy for active voltage regulators at the same voltage level and higher voltage levels. This makes the entire topology compact, significantly reducing the number of energy harvesting transformers and three-winding converter transformers in the DC converter station, reducing the footprint, lowering the design difficulty, size, and cost of high-end converter transformers, and improving the technical and economic efficiency of active voltage regulators in ultra-high voltage converter stations. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a composition diagram of a specific example of the active voltage regulation topology of a high-voltage direct current converter station provided in an embodiment of the present invention;

[0020] Figure 2 This is a composition diagram of another specific example of the active voltage regulation topology of the high-voltage DC converter station provided in the embodiments of the present invention;

[0021] Figure 3 This is a composition diagram of another specific example of the active voltage regulation topology of the high-voltage DC converter station provided in the embodiments of the present invention;

[0022] Figure 4 A composition diagram of a specific example of an energy harvesting transformer provided in an embodiment of the present invention;

[0023] Figure 5 This is a composition diagram of a specific example of an active voltage regulation system provided in an embodiment of the present invention.

[0024] Figure label:

[0025] 1-Active voltage regulation topology of high-voltage DC converter station; 11-Dual-winding converter transformer; 12-Three-winding converter transformer; 13-Energy harvesting transformer; 14-Active voltage regulator; 15-First converter; 16-Second converter; 111-First grid-side winding; 112-First valve-side winding; 121-Second grid-side winding; 122-Second valve-side winding; 123-Energy harvesting winding; 141-First anti-parallel thyristor module; 142-Back-to-back converter sub-module; 143-Bypass system; 1421-Rectifier module; 1422-DC capacitor; 1423-Inverter module; 1431-Mechanical switch; 1432-Second anti-parallel thyristor module. Detailed Implementation

[0026] 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1

[0031] This invention provides an active voltage regulation topology for a high-voltage direct current converter station, such as... Figure 1 As shown, it includes: a two-winding converter transformer 11, a three-winding converter transformer 12, an energy extraction transformer 13, an active voltage regulator 14, a first converter 15, and a second converter 16.

[0032] like Figure 1 As shown, the first end of the primary side of the dual-winding converter transformer 11 is connected to the AC bus, the second end of the primary side of the dual-winding converter transformer 11 is connected to the first end of the inverter side of an active voltage regulator 14, and the secondary side of the dual-winding converter transformer 11 is correspondingly connected to the AC side of the first converter 15.

[0033] like Figure 1 As shown, the first end of the primary side of the three-winding converter transformer 12 is connected to the AC bus, the second end of the primary side of the three-winding converter transformer 12 is connected to the first end of the inverter side of an active voltage regulator 14, the first secondary side of the three-winding converter transformer 12 is connected to the AC side of the second converter 16, and the second secondary side of the three-winding converter transformer 12 is connected to both ends of the primary side of the energy harvesting transformer 13.

[0034] like Figure 1As shown, the second terminal on the inverter side of the active voltage regulator 14 is connected to the neutral point or grounded. Figure 1 (Only the grounding method is shown in the figure). The rectifier side of the active voltage regulator 14 is connected to the secondary side of the energy harvesting transformer 13. The DC side of the first converter 15 is connected in series with the DC side of the second converter 16 to output the power supply voltage.

[0035] Specifically, in this embodiment of the invention, the first converter 15 and the second converter 16 are both six-pulse converters, and the above-mentioned parts can be combined to form a complete twelve-pulse converter unit for high voltage direct current transmission.

[0036] Specifically, by controlling the operating state of the active voltage regulator 14, the output voltage of the dual-winding converter transformer 11 and the three-winding converter transformer 12 is controlled, and finally the DC output voltage of the first converter 15 and the second converter 16 is adjusted.

[0037] Specifically, the energy-taking transformer 13 draws energy from the three-winding converter transformer 12 and then supplies energy to the active voltage regulator 14.

[0038] Specifically, in this embodiment of the invention, the energy-harvesting transformer 13 provides energy to the active voltage regulator 14 at the current voltage level and a higher voltage level. Utilizing... Figure 1 As shown in the topology, the entire converter station only needs to be configured with half of the three-winding converter transformers 12 and energy extraction transformers 13. The high-end converter transformer only needs to adopt a two-winding structure, which makes the entire topology compact, greatly reduces the number of energy extraction transformers 13 and three-winding converter transformers 12 in the DC converter station, reduces the footprint, reduces the design difficulty, volume and cost of the high-end converter transformer, and improves the technical and economic efficiency of the active voltage regulator 14 in the application of UHV converter stations.

[0039] In one specific embodiment, such as Figure 2 As shown, the dual-winding converter transformer 11 includes: a first grid-side winding 111 and a first valve-side winding 112.

[0040] like Figure 2 As shown, the first end of the first grid-side winding 111 is connected to the AC bus, and the second end of the first grid-side winding 111 is connected to the first end of the inverter side of an active voltage regulator 14; the two ends of the first valve-side winding 112 are correspondingly connected to the AC side of the first converter 15.

[0041] Specifically, in this embodiment of the invention, the active voltage regulator 14 is installed on the first grid winding 111 side and is at a low potential, which effectively reduces the insulation requirements and current requirements of the active voltage regulator 14.

[0042] Specifically, the AC system provides power to the dual-winding converter transformer 11 by connecting to the first grid-side winding 111 of the dual-winding converter transformer 11. An active voltage regulator 14 is connected in series between the end of the grid-side winding of the dual-winding converter transformer 11 and ground G. The voltage of each winding of the dual-winding converter transformer 11 is adjusted by the amplitude and phase of the output voltage of the active voltage regulator 14, and finally the DC output voltage of the six-pulse converter (first converter 15) is adjusted.

[0043] In one specific embodiment, such as Figure 2 As shown, the three-winding converter transformer 12 includes: a second grid-side winding 121, a second valve-side winding 122, and an energy extraction winding 123.

[0044] like Figure 2 As shown, the first end of the second grid-side winding 121 is connected to the AC bus, and the second end of the primary side of the second grid-side winding 121 is connected to the first end of the inverter side of an active voltage regulator 14; the two ends of the second valve-side winding 122 are correspondingly connected to the AC side of the second converter 16; and the two ends of the energy harvesting winding 123 are correspondingly connected to the two ends of the primary side of the energy harvesting transformer 13.

[0045] Specifically, the AC system provides power to the three-winding converter transformer 12 by connecting to the second grid-side winding 121 of the three-winding converter transformer 12. An active voltage regulator 14 is connected in series between the end of the grid-side winding of the three-winding converter transformer 12 and ground G. The voltage of each winding of the two-winding converter transformer 11 is adjusted by the amplitude and phase of the output voltage of the active voltage regulator 14, and finally the DC output voltage of the six-pulse converter (second converter 16) is adjusted.

[0046] Specifically, the energy extraction transformer 13 extracts energy from the energy extraction winding 123. The energy extraction transformer 13 is also connected to the active voltage regulator 14 of the two-winding converter transformer 11 and the active voltage regulator 14 of the three-winding converter transformer 12, and provides power and active power support to the active voltage regulator 14.

[0047] like Figure 2As shown, in this embodiment of the invention, an active voltage regulator 14 is connected in series between the end of the first grid-side winding 111 of the two-winding converter transformer 11 and ground G. Specifically, by adjusting the output voltage of the active voltage regulator 14, the voltage across the first grid-side winding 111 is adjusted, and simultaneously the output voltage of the first valve-side winding 112 is changed, achieving rapid, continuous, and precise adjustment of the voltage amplitude and phase of the two-winding converter transformer 11. Similarly, an active voltage regulator 14 is connected in series between the end of the second grid-side winding 121 of the three-winding converter transformer 12 and ground. Specifically, by adjusting the output voltage of the active voltage regulator 14, the voltage across the second grid-side winding 121 is adjusted, and simultaneously the output voltage of the second valve-side winding 122 is changed, achieving rapid, continuous, and precise adjustment of the voltage amplitude and phase of the three-winding converter transformer 12.

[0048] For example, in Figure 2 As shown, the 800kV converter transformer is designed with two structures: three-winding and two-winding. The voltage level of the two grid-side windings is 500kV, and the voltage level of the two valve-side windings is DC 800kV. The rated capacity of the converter transformer is 509MVA. Compared with the three-winding scheme with the energy extraction winding 123, the two-winding scheme without the energy extraction winding 123 reduces the length dimension of the transformer by 1m, the volume of the transformer tank will be reduced by 5%, and the total weight will be reduced by 11 tons. At the same time, due to the limitation of transportation size, the insulation margin of the three-winding converter transformer 12 with the energy extraction winding 123 is reduced. Due to the introduction of the energy extraction winding 123, the safety margin of the main insulation and the safety margin of the short-circuit withstand force between the energy extraction winding 123 and the core are the lowest. By removing the energy extraction winding 123, the safety margin of the converter transformer can be effectively improved, and the volume and weight can be reduced.

[0049] In one specific embodiment, such as Figure 3 As shown, the active voltage regulator 14 includes: multiple first anti-parallel thyristor modules 141 and multiple cascaded back-to-back commutator submodules 142.

[0050] like Figure 3 As shown, the inverter side of each back-to-back converter submodule 142 is connected in parallel with a first anti-parallel thyristor module 141; the first end (A end) of the cascaded inverter side of each back-to-back converter submodule 142 is connected to the second end of the primary side of the three-winding converter transformer; the second end of the cascaded inverter side of each back-to-back converter submodule 142 is connected to the neutral point or grounded; and the rectifier side of each back-to-back converter submodule 142 is correspondingly connected to the secondary side of the energy harvesting transformer 13.

[0051] Specifically, embodiments of the present invention can achieve different voltage levels by changing the number of cascaded back-to-back converter submodules 142. Simultaneously, cascading multiple back-to-back converter submodules 142 can reduce harmonic content. The back-to-back converter submodules 142, based on fully controllable power electronic devices, enable flexible control of output voltage amplitude and phase, greatly improving the response speed of active voltage regulation and providing a new solution to the voltage fluctuation problem caused by continuous fluctuations in new energy sources.

[0052] In one specific embodiment, such as Figure 3 As shown, the back-to-back converter submodule 142 includes: a rectifier module 1421, a DC capacitor 1422, and an inverter module 1423.

[0053] like Figure 3 As shown, the AC side of the rectifier module 1421 is connected to the secondary side of the energy harvesting transformer 13, and the DC side of the rectifier module 1421 is connected in parallel with the DC capacitor 1422; the DC side of the inverter module 1423 is connected to the DC side of the rectifier module 1421, and a first anti-parallel thyristor module 141 is connected in parallel on the AC side of the inverter module 1423; the AC side of the inverter module 1423 is also cascaded with the AC side of the inverter module 1423 of the adjacent back-to-back converter submodule 142.

[0054] In one specific embodiment, such as Figure 3 As shown, the active voltage regulator 14 also includes a bypass system 143, wherein the bypass system is connected in parallel to the two ends of the inverter side of each back-to-back converter submodule 142 after being cascaded; the bypass system is used to bypass the active voltage regulator 14.

[0055] Specifically, when the active voltage regulator 14 fails, the bypass system bypasses it to ensure that the two-winding converter transformer 11 and the three-winding converter transformer 12 can continue to operate normally.

[0056] Optionally, such as Figure 3 As shown, the bypass system includes a mechanical switch 1431 and a second anti-parallel thyristor module 1432, wherein the mechanical switch 1431 and the second anti-parallel thyristor module 1432 are connected in parallel.

[0057] In one specific embodiment, such as Figure 2 As shown, the energy extraction transformer 13 includes a primary winding and multiple secondary windings, wherein the primary winding is connected to both ends of the second secondary winding of the three-winding converter transformer 12; each secondary winding is connected to both ends of the rectifier side of a back-to-back converter submodule 142 of an active voltage regulator 14.

[0058] For example, such as Figure 4As shown, taking the energy harvesting transformer 13 with three secondary windings as an example, the energy harvesting transformer 13 includes a primary winding 131, a secondary winding #1321, a secondary winding #1322, and a secondary winding #1323. The input terminal of the primary winding is connected to the output terminal of the energy harvesting winding 123 of the three-winding converter transformer 12. The secondary winding #1321 is connected to the rectifier terminals of the back-to-back converter submodules #1421 and #1424, respectively. The secondary winding #1322 is connected to the rectifier terminals of the back-to-back converter submodules #1422 and #1425, respectively. The secondary winding #1323 is connected to the rectifier terminals of back-to-back converter submodules #1423 and #1426 respectively. Back-to-back converter submodules #1421, #1422 and #1423 are cascaded and connected to the end of the first grid-side winding 111 of the dual-winding converter transformer 11 and ground. Back-to-back converter submodules #1424, #1425 and #1426 are cascaded and connected to the end of the second grid-side winding 121 of the three-winding converter transformer 12 and ground. The secondary windings #1321, #1322, and #1323 of the energy harvesting transformer 13 can simultaneously provide energy for the converter modules required by the two-winding converter transformer 11 and the three-winding converter transformer 12. Compared with configuring energy harvesting windings 123 for each converter transformer and multi-winding energy harvesting transformer 13, the number of three-winding converter transformers 12 and energy harvesting transformers 13 can be reduced by half. Moreover, the energy harvesting transformer 13 can simultaneously provide energy for the active voltage regulator 14 of this voltage level and the active voltage regulator 14 of a higher voltage level. It has a compact structure, greatly reduces the footprint, reduces costs, and improves technical and economic efficiency.

[0059] Example 2

[0060] This invention provides an active voltage regulation system for a high-voltage direct current converter station, such as... Figure 5 As shown, it includes: multiple active voltage regulation topologies 1 of high voltage DC converter stations according to Embodiment 1, wherein the input terminal of each active voltage regulation topology 1 of the high voltage DC converter station is connected to the AC bus, and the output terminals of each active voltage regulation topology 1 of the high voltage DC converter station are connected in series.

[0061] It should be noted that, Figure 5 The example only uses the active voltage regulation topology 1 of two high-voltage DC converter stations, but it is not intended to be a limitation.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An active voltage regulation topology for a high-voltage direct current converter station, characterized in that, include: The system includes a two-winding converter transformer, a three-winding converter transformer, an energy extraction transformer, an active voltage regulator, a first converter, and a second converter. The first end of the primary side of the dual-winding converter transformer is connected to the AC bus, the second end of the primary side of the dual-winding converter transformer is connected to the first end of the inverter side of one of the active voltage regulators, and the secondary side of the dual-winding converter transformer is correspondingly connected to the AC side of the first converter. The first end of the primary side of the three-winding converter transformer is connected to the AC bus, the second end of the primary side of the three-winding converter transformer is connected to the first end of the inverter side of one of the active voltage regulators, the first secondary side of the three-winding converter transformer is connected to the AC side of the second converter, and the second secondary side of the three-winding converter transformer is connected to both ends of the primary side of the energy harvesting transformer. The second terminal of the inverter side of the active voltage regulator is connected to the neutral point or grounded, and the rectifier side of the active voltage regulator is connected to the secondary side of the energy harvesting transformer. The DC side of the first converter and the DC side of the second converter are connected in series to output the supply voltage; The energy-harvesting transformer draws energy from the three-winding converter transformer and supplies energy to the active voltage regulator; by controlling the operating state of the active voltage regulator, the output voltage of the two-winding converter transformer and the three-winding converter transformer is controlled. The active voltage regulator includes: multiple first anti-parallel thyristor modules and multiple cascaded back-to-back converter submodules, wherein the inverter side of each converter submodule is connected in parallel with a first anti-parallel thyristor module; the first end of the cascaded inverter side of each back-to-back converter submodule is connected to the second end of the primary side of the three-winding converter transformer; the second end of the cascaded inverter side of each back-to-back converter submodule is connected to the neutral point or grounded; and the rectifier side of each back-to-back converter submodule is correspondingly connected to the secondary side of the energy harvesting transformer. The active voltage regulator further includes a bypass system, wherein the bypass system is connected in parallel to both ends of the inverter side of each of the back-to-back converter submodules after cascading; the bypass system is used to bypass the active voltage regulator. The dual-winding converter transformer includes a first grid-side winding and a first valve-side winding, wherein a first end of the first grid-side winding is connected to an AC bus, and a second end of the first grid-side winding is connected to a first end of the inverter side of an active voltage regulator; the two ends of the first valve-side winding are correspondingly connected to the AC side of the first converter.

2. The active voltage regulation topology of the high-voltage DC converter station according to claim 1, characterized in that, The three-winding converter transformer includes: a second grid-side winding, a second valve-side winding, and an energy extraction winding, wherein... The first end of the second grid-side winding is connected to the AC bus, and the second end of the primary side of the second grid-side winding is connected to the first end of the inverter side of one of the active voltage regulators. The two ends of the second valve-side winding are connected to the AC side of the second converter respectively; The two ends of the energy harvesting winding are connected to the two ends of the primary side of the energy harvesting transformer.

3. The active voltage regulation topology of the high-voltage DC converter station according to claim 1, characterized in that, The back-to-back converter submodule includes: a rectifier module, a DC capacitor, and an inverter module, wherein... The AC side of the rectifier module is connected to the secondary side of the energy harvesting transformer, and the DC side of the rectifier module is connected in parallel with the DC capacitor. The DC side of the inverter module is connected to the DC side of the rectifier module. A first anti-parallel thyristor module is connected in parallel on the AC side of the inverter module. The AC side of the inverter module is also cascaded with the AC side of the inverter module of the adjacent back-to-back converter submodule.

4. The active voltage regulation topology of the high-voltage DC converter station according to claim 1, characterized in that, The bypass system includes: a mechanical switch and a second anti-parallel thyristor module, wherein... The mechanical switch is connected in parallel with the second anti-parallel thyristor module.

5. The active voltage regulation topology of the high-voltage direct current converter station according to claim 1, characterized in that, The energy extraction transformer includes: a primary winding and multiple secondary windings, wherein... The primary winding is connected to both ends of the second secondary winding of the three-winding converter transformer. Each of the secondary windings is connected to the two ends of the rectifier side of a back-to-back commutator submodule of an active voltage regulator.

6. An active voltage regulation system for a high-voltage direct current converter station, characterized in that, include: The active voltage regulation topology of the high-voltage direct current converter station according to any one of claims 1-5, wherein, The input terminal of each active voltage regulating topology of the HVDC converter station is connected to the AC bus, and the output terminals of each active voltage regulating topology of the HVDC converter station are connected in series.

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