Offshore wind power direct current grid-connected converter station

Abstract

The application discloses a kind of offshore wind power DC grid-connected converter station, including AC field, converter valve hall, bridge arm reactor and starting area, DC circuit breaker and energy consumption valve hall and DC field, AC field, converter valve hall, bridge arm reactor and starting area, DC circuit breaker and energy consumption valve hall and DC field are sequentially connected to make submarine cable by AC field access to the DC field DC transmission line transmission.The application can not need to set offshore converter station, offshore wind power AC power collection line is directly landed and converted into DC by converter station, and is accessed into DC power grid by DC line.

Description

Technical Field

[0001] This invention belongs to the field of offshore wind power generation and flexible DC transmission technology, and particularly relates to an offshore wind power DC grid-connected converter station. Background Technology

[0002] With the acceleration of the global energy transition, offshore wind power has become a key area for renewable energy development due to its abundant resources, high utilization hours, and proximity to load centers. In recent years, offshore wind power has been developing towards large-scale, offshore, and clustered development, with wind farm capacity continuously increasing and distance from shore constantly growing. When the transmission distance exceeds a certain threshold, traditional AC grid connection schemes suffer from problems such as large cable charging capacitor current, limited transmission capacity, high reactive power compensation requirements, and system stability challenges, leading to a significant decline in their economic and technical feasibility. Therefore, high-voltage direct current (HVDC) transmission technology, especially flexible direct current transmission based on voltage source converters (VSC-HVDC), has become the dominant technology solution for grid connection of offshore, large-capacity wind farms.

[0003] Currently, the mainstream offshore wind power DC grid-connected system adopts the "AC collection-offshore converter-DC transmission" mode: the wind turbine generates AC power, which is collected by the offshore AC collection network and sent to the offshore converter station, where it is stepped up and converted into DC power. Then, it is transmitted to the onshore converter station via submarine DC cables, and finally inverted back into AC power and connected to the main grid. Although this mode is mature, the offshore converter station, as a key link, faces a series of challenges, including extremely high investment costs, difficulty in constructing and installing offshore platforms, difficulties in operation and maintenance, and reliability affected by the harsh marine environment. These challenges have become important factors restricting the economic development of offshore wind power.

[0004] In light of this, to simplify system structure, reduce total lifecycle costs, and improve system availability, the industry has begun exploring optimized solutions for "AC aggregation-DC transmission," which eliminates the need for expensive offshore converter station platforms. However, existing solutions mostly focus on the direct DC conversion of wind turbines or aggregation stages (such as using DC wind turbines or AC aggregation followed by compact DC / DC converter boosting), which have low technological maturity and poor compatibility with existing mainstream AC wind turbines, making large-scale application difficult in the short term.

[0005] Currently, there is a lack of practical grid connection schemes that can fully utilize existing mature AC wind turbines and AC power collection technologies, avoid the construction of offshore converter station platforms, and directly connect offshore wind power to distant DC power grids. Especially when wind farms are located relatively close to the coast and their AC power collection lines are feasible for direct landing, how to utilize this condition to achieve key power conversion and grid connection functions on land has significant research value and engineering implications. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems existing in the prior art and to provide an offshore wind power DC grid-connected converter station that can convert offshore wind power AC collection lines directly into DC power after landing at the converter station without the need to set up an offshore converter station, and then connect to the DC grid through DC lines.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A DC grid-connected converter station for offshore wind power includes an AC field, a converter valve hall, a bridge arm reactor and start-up area, a DC circuit breaker and energy dissipation valve hall, and a DC field. The AC field, converter valve hall, bridge arm reactor and start-up area, DC circuit breaker and energy dissipation valve hall, and DC field are sequentially connected so that submarine cables are connected from the AC field to the DC transmission line of the DC field. The AC field includes a GIS room, a connecting transformer, and a neutral point device. The converter valve hall includes converter valves, AC busbars, current measuring devices, surge arresters, and grounding switches. The bridge arm reactor and start-up area includes bridge arm reactors, DC busbars, DC starting resistors, and DC fast switches. The DC circuit breaker and energy dissipation valve hall includes DC circuit breakers, energy dissipation valves, grounding switches, and DC current measuring devices. The DC field includes current-limiting reactors, DC disconnect switches, DC energy dissipation resistors, DC current measuring devices, DC voltage measuring devices, and DC surge arresters.

[0008] As one implementation method, the indoor GIS room is equipped with a 66kV AC power distribution device and a 220kV AC power distribution device. The 66kV AC power distribution device includes a submarine cable incoming section, a connecting transformer outgoing section, and a busbar section. The submarine cable incoming section is connected to the submarine cable of the 66kV offshore wind power collection line. The connecting transformer outgoing section is connected to the low-voltage side of the connecting transformer via a branch busbar and an air bushing. The 220kV AC power distribution device includes a connecting transformer incoming section and a converter valve outgoing section. The connecting transformer incoming section is connected to the high-voltage side of the connecting transformer via a branch busbar and an air bushing. The converter valve outgoing section is connected to the AC busbar of the converter valve hall via a branch busbar.

[0009] As one implementation method, the connecting transformer is a double-winding transformer, installed outdoors. Both the low-voltage and high-voltage sides of the connecting transformer are equipped with a neutral point assembly, which is connected to the connecting transformer via a flexible conductor. Both the high-voltage and low-voltage side neutral point assemblies include resistors, current transformers, and surge arresters.

[0010] As one implementation method, the six converter valve bridge arms in the converter valve hall can be arranged in phase sequence A+B+C+ABC- or A+B+C+CBA-. The A-phase AC busbar and the B-phase AC busbar adopt a suspended busbar, and the C-phase AC busbar adopts a supported busbar. They are connected to the bridge arm converter valves through flexible conductors and current measuring devices. Current measuring devices, surge arresters and grounding switches are installed below the AC busbars. The DC side outgoing lines of the six converter valves are equipped with current measuring devices, surge arresters and grounding switches and connected to the bridge arm reactors and the starting area.

[0011] As one implementation, six bridge arm reactors are installed in the bridge arm reactor and starting area. The three positive bridge arm reactors are connected to the positive DC busbar, and the three negative bridge arm reactors are connected to the negative DC busbar. Their phase sequence is the same as that of the converter valve. A DC starting resistor is installed in both the positive and negative pole circuits. One side is connected to the DC circuit breaker and energy dissipation valve hall via a DC fast switch, and the other side is connected to the DC busbar via a DC measuring device. The DC starting resistor is connected in parallel with a DC disconnecting switch. A surge arrester, a grounding switch, and a DC voltage measuring device are installed below the DC busbar. A current-limiting energy dissipation reactor is installed in both the positive and negative energy dissipation circuits. One side is connected to the DC busbar via a DC disconnecting switch, and the other side is connected to the DC circuit breaker and energy dissipation valve hall via a DC through-wall bushing.

[0012] As one implementation method, a DC circuit breaker and an energy-consuming valve are installed at both the positive and negative poles of the DC circuit breaker and energy-consuming valve hall, arranged symmetrically in the same room. The grounding switches and DC current measuring devices on both sides of the DC circuit breaker are connected to the DC field. The energy-consuming valve is equipped with a grounding switch and a DC current measuring device on the side near the energy-consuming current-limiting reactor and is connected to the DC field.

[0013] As one implementation method, a current-limiting reactor is installed at both the positive and negative poles of the DC field, arranged on both sides of the DC field area, and connected to the DC transmission line after passing through a DC disconnect switch, a DC current measuring device, a DC voltage measuring device, and a DC surge arrester; the DC energy-consuming resistor is connected to the energy-consuming valve and is connected between the positive and negative energy-consuming valves, and is installed outdoors.

[0014] As one implementation method, the DC transmission line can be an overhead line or a DC cable, connected to the converter station of the power system on the other side.

[0015] As one implementation method, it also includes a production support area, which includes the main control building and cooling tower.

[0016] As one implementation method, the main control building includes a station power supply room, valve control room, communication and relay protection room, central control room, valve cooling control room, valve cooling equipment room, and DC circuit breaker UPS room, which serve as an auxiliary for the offshore wind power DC grid-connected converter station to perform system control, system protection, equipment cooling, and equipment power supply.

[0017] The present invention, by adopting the above-described technical solution, has the following beneficial effects: This invention connects the AC field, converter valve hall, bridge arm reactor and start-up area, DC circuit breaker and energy dissipation valve hall and DC field in sequence so that the submarine cable is connected from the AC field to the DC transmission line of the DC field and sent out. There is no need to set up an offshore converter station. The offshore wind power AC collection line is directly landed and converted into DC power by the converter station. The DC power is then connected to the DC grid through the DC line, realizing the transmission of large-capacity offshore wind power. The compact layout reduces the land area and lowers the cost. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of an offshore wind power DC grid-connected converter station according to the present invention; Figure 2 This is a plan view of the present invention; Figure 3 This is a schematic diagram of the structure of the AC field in this invention; Figure 4 This is a schematic diagram of the converter valve chamber in this invention; Figure 5 This is a schematic diagram of the bridge arm reactor and the starting area in this invention; Figure 6 This is a schematic diagram of the structure of the DC circuit breaker and energy-consuming valve hall in this invention; Figure 7 This is a schematic diagram of the DC field 500 in this invention. Detailed Implementation

[0019] like Figures 1 to 7As shown, this invention discloses a DC grid-connected converter station for offshore wind power, comprising an AC field 100, a converter valve hall 200, a bridge arm reactor and start-up area 300, a DC circuit breaker and energy-consuming valve hall 400, and a DC field 500. The AC field 100, converter valve hall 200, bridge arm reactor and start-up area 300, DC circuit breaker and energy-consuming valve hall 400, and DC field 500 are sequentially connected so that submarine cables are connected from the AC field 100 to the DC transmission line of the DC field 500. The AC field 100 includes a GIS room 101, a connecting transformer 110, and a neutral point device 111. The converter valve hall 200 includes a converter valve 201. The AC busbar 202, current measuring device 203, surge arrester 204, and grounding switch 205; the bridge arm reactor and starting area 300 includes bridge arm reactor 301, DC busbar 302, DC starting resistor 303, and DC fast switch 304; the DC circuit breaker and energy dissipation valve hall 400 includes DC circuit breaker 401, energy dissipation valve 402, grounding switch 403, and DC current measuring device 404; the DC field 500 includes current limiting reactor 501, DC disconnecting switch 502, DC energy dissipation resistor 503, DC current measuring device 504, DC voltage measuring device 505, and DC surge arrester 506. The AC field 100, converter valve hall 201, bridge arm reactor and starting area 300, DC circuit breaker and energy dissipation valve hall 402, and DC field 500 are arranged adjacent to each other according to the process flow. As one implementation method, the indoor GIS room 101 is equipped with a 66kV AC power distribution device 102 and a 220kV AC power distribution device 103, with both voltage levels arranged in the same room. The 66kV AC power distribution device 102 includes a submarine cable inlet bay, a connecting transformer outlet bay, and a bus bay. The submarine cable inlet bay is connected to the submarine cable of the 66kV offshore wind power collector line. The connecting transformer outlet bay is connected to the low-voltage side of the connecting transformer 110 via a branch busbar and an air bushing. The 220kV AC power distribution device 103 includes a connecting transformer inlet bay and a converter valve 201 outlet bay. The connecting transformer inlet bay is connected to the high-voltage side of the connecting transformer 110 via a branch busbar and an air bushing. The converter valve 201 outlet bay is connected to the AC busbar 202 of the converter valve 201 hall 200 via a branch busbar.

[0020] Furthermore, the connecting transformer 110 is a double-winding transformer, installed outdoors. Both the low-voltage and high-voltage sides of the connecting transformer 110 are equipped with a neutral point assembly 111, which is connected to the connecting transformer 110 by a flexible wire. Both the high-voltage and low-voltage side neutral point assemblies include resistors, current transformers, and surge arresters.

[0021] Furthermore, the six converter valve 201 bridge arms within the converter valve 201 hall 200 can be arranged in a phase sequence of A+B+C+ABC- or A+B+C+CBA-. The A-phase AC busbar 202-1 and B-phase AC busbar 202-2 are suspended busbars, while the C-phase AC busbar 202-3 is a supported busbar. These are connected to the bridge arm converter valve 201 via flexible conductors and a current measuring device 203. A current measuring device 203, a surge arrester, and a grounding switch are installed below the AC busbars. The DC side outgoing lines of the six converter valves 201 are equipped with a current measuring device 203, a surge arrester 204, and a grounding switch 205, and are connected to the bridge arm reactor 301 and the starting area 300. Sufficient maintenance space is reserved within the converter valve 201 hall 200 to accommodate the operation of the maintenance trolley.

[0022] Furthermore, six bridge arm reactors 301 are installed in the bridge arm reactor 301 and the starting area 300. Three positive bridge arm reactors 301 are connected to the positive DC busbar 302, and three negative bridge arm reactors 301 are connected to the negative DC busbar 302. Their phase sequence is the same as that of the converter valve 201. The positive and negative power distribution devices are symmetrically arranged within the bridge arm reactors 301 and the starting area 300. Each positive and negative pole circuit is equipped with a DC starting resistor 303. One side is connected to the DC circuit breaker 401 and the energy dissipation valve 402 via a DC fast switch 304 and a DC through-wall bushing 400. The other side is connected to the DC busbar 302 via a DC measuring device. The DC starting resistor 303 is connected in parallel with a DC disconnect switch 307, which is used to short-circuit the DC starting resistor 303 after charging is complete. A surge arrester 308, a grounding switch 309, and a DC voltage measuring device 310 are installed below the DC busbar 302. Both the positive and negative energy-consuming circuits are equipped with an energy-consuming current-limiting reactor 311, one side connected to the DC busbar 302 via a DC disconnect switch 307, and the other side connected to the DC circuit breaker 401 and energy-consuming valve 402 via a DC through-wall bushing. Sufficient transport space is reserved within the bridge arm reactor 301 and the starting area 300 to accommodate reactor handling.

[0023] Furthermore, one DC circuit breaker 401 and one energy-consuming valve 402 are installed at both the positive and negative terminals of the hall 400, arranged symmetrically within the same room. The grounding switches and DC current measuring devices 404 on both sides of the DC circuit breaker 401 are connected to the DC field 500. The energy-consuming valve 402 has a grounding switch and a DC current measuring device 404 on the side near the energy-consuming current-limiting reactor 501, and is connected to the DC field 500. The energy-consuming valve 402 has a grounding switch and a DC current measuring device 203 on the side near the energy-consuming current-limiting reactor 501, and is connected to the DC field 500 via an energy-consuming DC through-wall bushing on the side near the DC field 500. Sufficient maintenance space is reserved within the halls of the DC circuit breaker 401 and the energy-consuming valve 402 to accommodate the operation of the maintenance trolley.

[0024] Furthermore, a current-limiting reactor 501 is installed at both the positive and negative poles of the DC field 500, located on both sides of the DC field 500 area. It is connected to the DC transmission line via a DC disconnect switch 502, a DC current measuring device 504, a DC voltage measuring device, and a DC surge arrester. The DC energy-consuming resistor 503 is connected to the energy-consuming valve 402 via an energy-consuming DC through-wall bushing, and is connected between the positive and negative energy-consuming valves 402. It is installed outdoors.

[0025] Furthermore, the DC transmission line can be an overhead line or a DC cable, connecting to the power system converter station on the other side.

[0026] Furthermore, it also includes a production auxiliary area 600, which comprises a main control building 301 and a cooling tower 302. The production auxiliary area is located on one side of the overall power distribution area.

[0027] Furthermore, the main control building 601 includes a station power supply room, valve control room, communication and relay protection room, central control room, valve cooling control room, valve cooling equipment room, and DC circuit breaker UPS room, serving as an auxiliary facility for system control, system protection, equipment cooling, and equipment power supply for the offshore wind power DC grid-connected converter station. The cooling tower is located adjacent to the main control building and is connected to the valve cooling equipment room within the main control building via pipes, using water cooling to cool the converter valve 201 and the DC circuit breaker 401.

[0028] This invention connects the AC field 100, converter valve 201 (hall 200), bridge arm reactor 301 and start-up zone 300, DC circuit breaker 401 and energy dissipation valve 402 (hall 400), and DC field 500 in sequence so that the submarine cable is connected from the AC field 100 to the DC transmission line of the DC field 500 for transmission. There is no need to set up an offshore converter station. After the offshore wind power AC collection line lands directly, it is converted into DC power by the converter station and connected to the DC grid through the DC line, realizing the transmission of large-capacity offshore wind power. Through compact layout, the land area used is reduced and the construction cost is lowered.

[0029] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A DC grid-connected converter station for offshore wind power, characterized in that: The system includes an AC field (100), a converter valve hall (200), a bridge arm reactor and starting area (300), a DC circuit breaker and energy dissipation valve hall (400), and a DC field (500). The AC field (100), the converter valve hall (200), the bridge arm reactor and starting area (300), the DC circuit breaker and energy dissipation valve hall (400), and the DC field (500) are sequentially connected so that the submarine cable is connected from the AC field (100) to the DC transmission line of the DC field (500). The AC field (100) includes a GIS room (101), a connecting transformer (110), and a neutral point device. The converter valve hall (200) includes a converter valve (201), an AC bus (202), and an electrical... The system includes a current measuring device (203), a surge arrester (204), and a grounding switch (205). The bridge arm reactor and starting area (300) include a bridge arm reactor (301), a DC busbar (302), a DC starting resistor (303), and a DC fast switch (304). The DC circuit breaker and energy dissipation valve hall (400) includes a DC circuit breaker (401), an energy dissipation valve (402), a grounding switch (403), and a DC current measuring device (404). The DC field (500) includes a current limiting reactor (501), a DC disconnecting switch (502), a DC energy dissipation resistor (503), a DC current measuring device (504), a DC voltage measuring device (505), and a DC surge arrester (506).

2. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The indoor GIS room (101) is equipped with a 66kV AC power distribution device (102) and a 220kV AC power distribution device (103). The 66kV AC power distribution device (102) is equipped with a submarine cable inlet bay, a connecting transformer outlet bay and a bus bay. The submarine cable inlet bay is connected to the submarine cable of the 66kV offshore wind power collection line. The connecting transformer outlet bay is connected to the low-voltage side of the connecting transformer (110) via a branch bus and an air bushing. The 220kV AC power distribution device (103) is equipped with a connecting transformer inlet bay and a converter valve (201) outlet bay. The connecting transformer inlet bay is connected to the high-voltage side of the connecting transformer (110) via a branch bus and an air bushing. The converter valve (201) outlet bay is connected to the AC bus (202) of the converter valve hall (200) via a branch bus.

3. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The connecting transformer (110) is a double-winding transformer, which is installed outdoors. The low-voltage side and the high-voltage side of the connecting transformer (110) are equipped with a neutral point assembly. The neutral point assembly is connected to the connecting transformer (110) by a flexible wire.

4. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The six converter valves (201) bridge arms in the converter valve hall (200) can be arranged in a phase sequence of A+B+C+ABC- or A+B+C+CBA-. The A-phase AC busbar (202-1) and the B-phase AC busbar (202-2) are suspended busbars, and the C-phase AC busbar (202-3) is a supported busbar. They are connected to the bridge arm converter valves (201) through flexible wires and current measuring devices (204). A current measuring device (203), a surge arrester (204), and a grounding switch (205) are installed below the AC busbars. The DC side outputs of the six converter valves (201) are equipped with a current measuring device (203), a surge arrester (204), and a grounding switch (205) and are connected to the bridge arm reactor (301) and the starting area (300).

5. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The bridge arm reactor (301) and the starting area (300) are equipped with six bridge arm reactors (301). Three of the positive bridge arm reactors (301) are connected to the positive DC busbar (302), and three of the negative bridge arm reactors (301) are connected to the negative DC busbar (302). Their phase sequence is the same as that of the converter valve (201). Both the positive and negative pole circuits are equipped with a DC starting resistor (303), one side of which is connected to the DC circuit breaker (401) and the energy-consuming valve hall (400) via a DC fast switch (304). One side is connected to the DC busbar (302) via the DC measuring device. The DC starting resistor (303) is connected in parallel with the DC disconnect switch (307). A surge arrester (308), a grounding switch (309), and a DC voltage measuring device (310) are installed below the DC busbar (302). A current-limiting reactor (311) is installed in both the positive and negative energy-consuming circuits. One side is connected to the DC busbar (302) via the DC disconnect switch (307), and the other side is connected to the DC circuit breaker and energy-consuming valve hall (400) via the DC through-wall bushing (305).

6. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The DC circuit breaker (401) and the energy-consuming valve hall (400) are each equipped with one DC circuit breaker (401) and one energy-consuming valve (402) at the positive and negative poles, respectively, and are arranged symmetrically in the same room. The grounding switch (403) and DC current measuring device (404) on both sides of the DC circuit breaker (401) are connected to the DC field (500). The energy-consuming valve (402) is equipped with a grounding switch (403) and a DC current measuring device (404) on the side near the energy-consuming current-limiting reactor (501) and is connected to the DC field (500).

7. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: One current-limiting reactor (501) is installed at each of the positive and negative poles of the DC field (500), arranged on both sides of the DC field (500) area, and connected to the DC transmission line after passing through the DC disconnect switch (502), the DC current measuring device (504), the DC voltage measuring device (505) and the DC surge arrester (506); the DC energy-consuming resistor (503) is connected to the energy-consuming valve (402) and is connected between the positive and negative energy-consuming valves (402), and is arranged outdoors.

8. The offshore wind power DC grid-connected converter station according to claim 1, characterized in that: The DC transmission line can be an overhead line or a DC cable, connecting to the power system converter station on the other side.

9. A DC grid-connected converter station for offshore wind power according to claim 1, characterized in that: It also includes a production support area (600), which includes a main control building (601) and a cooling tower (602).

10. A DC grid-connected converter station for offshore wind power according to claim 1, characterized in that: The main control building includes a station power supply room, valve control room, communication and relay protection room, central control room, valve cooling control room, valve cooling equipment room, and DC circuit breaker UPS room, serving as an auxiliary facility for system control, system protection, equipment cooling, and equipment power supply of the offshore wind power DC grid-connected converter station.

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