High-capacity offshore converter station power utilization system and control method

Abstract

The invention provides a high-capacity offshore converter station power utilization system and a control method, and the system is provided with two paths of high-voltage working power supplies which are connected to a working section through an incoming line circuit breaker; two paths of 10kV high-voltage emergency power generation units are switched through ATS automatic change-over switch equipment and then are connected to a 10kV emergency section, and a 10kV working section is connected with the 10kV emergency section through a 10kV interconnecting circuit breaker to form single-bus three-section wiring. A plurality of 400V power centers are arranged, two paths of 10kV working power supplies of each power center are respectively led from two working sections, are reduced to 400V through a station transformer and are accessed to the working sections of the power center through incoming line breakers, and the working sections are connected through 400V interconnecting breakers to form single-bus sectional wiring. A single-bus three-section 10kV wiring mode is arranged, and a two-way high-voltage power supply is increased to a three-way high-voltage power supply, so that the reliability of a power utilization system of the whole station is improved; a plurality of 400V power centers are arranged, the number of the power centers can be expanded according to project requirements, limiting factors do not exist, and expansibility is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of offshore wind power generation, and particularly relates to a large-capacity offshore converter station station power system and a control method. BACKGROUND

[0002] Offshore wind power has the characteristics of advanced technology, rich resources, and high number of power generation hours, and is the direction of future energy development. With the development of offshore wind power to deep and far seas, the development scale of offshore wind power is increasing, from 10-50 million kilowatts to millions of kilowatts, such as 2 million kilowatts, 3 million kilowatts, or even higher capacity. The increase in the development scale has led to the update and iteration of the power transmission scheme. For large-scale and long-distance offshore wind power, flexible direct current transmission technology is currently a selectable scheme with both technical and economic advantages. The design and safe and stable operation of the station power system of the offshore converter station in the flexible power transmission technology are of great importance.

[0003] The existing offshore converter station station power system includes two 10kV station power supply incoming lines, two 10kV working sections, two 400V power centers, and one 400V standby power supply. The 10kV working section is connected with the 10kV station power supply incoming line, the two 400V power centers are connected with the 10kV working section through a station transformer, the two power centers are connected through a tie circuit breaker, and the 400V standby power supply is connected with the power center through 8 400V power cables.

[0004] The existing technology is based on a million kilowatt level offshore converter station, and the considered station power load is relatively small, the number of power centers is 2, the capacity of the diesel generator is small, and the voltage level is 400V. In the future, the scale of the offshore converter station will reach 2 million-3 million kilowatts or more, the station power load will reach or exceed 10MW, and the capacity of the diesel generator will reach or exceed 2MW. If the existing station power connection is used, the large-capacity diesel generator is only connected to a single power center, and is connected with other power centers through a 400V tie switch. With the increase in the power load and the number of power centers, the number of tie switches and the number of connection cables will greatly increase, causing an increase in investment, congestion of cable channels of the offshore converter station, and a serious heating problem, and the reliability is reduced. In addition, with the increase in the capacity of the diesel generator, if the 400V voltage level is still used, the number of parallel diesel generator outgoing cables will also greatly increase, and the same problems of increased investment and reduced reliability exist. Moreover, due to the existence of the 400V tie switch, the increase in the number of power centers is limited.

[0005] Therefore, for the future large-capacity offshore converter station station power load, it is an important problem to be solved to design a safe and reliable, economically feasible large-capacity offshore converter station station power connection mode. SUMMARY

[0006] The first object of the present application is to provide a large-capacity offshore converter station power system to solve the above-mentioned problems.

[0007] To achieve the above object, the present application adopts the following technical solutions:

[0008] A large-capacity offshore converter station power system, comprising a first high-voltage power supply and a second high-voltage power supply, wherein the first high-voltage power supply is provided with a first high-voltage step-down transformer and a first 10kV incoming line circuit breaker and is connected to a first 10kV working section, and the second high-voltage power supply is provided with a second high-voltage step-down transformer and a second 10kV incoming line circuit breaker and is connected to a second 10kV working section.

[0009] A 10kV emergency section is arranged between the first 10kV working section and the second 10kV working section, and the 10kV emergency section is provided with a first diesel generator and a second diesel generator, and an ATS automatic transfer switch is arranged between the 10kV emergency section and the first diesel generator and the second diesel generator, and the 10kV emergency section is connected to the first 10kV working section and the second 10kV working section through a first 10kV tie circuit breaker and a second 10kV tie circuit breaker.

[0010] A plurality of 400V power centers are arranged between the first 10kV working section and the second 10kV working section, and two 10kV working power supplies of each power center are respectively led from the first 10kV working section and the second 10kV working section, and each 10kV working power supply is stepped down to 400V through a first station transformer and a second station transformer, and is connected to a first 400V working section and a second 400V working section of the power center through a first 400V incoming line circuit breaker and a second 400V incoming line circuit breaker, and a 400V tie circuit breaker is arranged between the first 400V working section and the second 400V working section.

[0011] In addition to the above technical solutions, the present application can also adopt or combine the following technical solutions:

[0012] As a preferred technical solution of the present application, the high-voltage side voltage level of the first high-voltage step-down transformer is matched with the offshore converter station, including 35kV, 66kV, 110kV, and 220kV voltage levels.

[0013] As a preferred technical solution of the present application, the high-voltage side voltage level of the second high-voltage step-down transformer is matched with the offshore converter station, including 35kV, 66kV, 110kV, and 220kV voltage levels.

[0014] As a preferred technical solution of the present application, the output voltage level of the first diesel generator is 10kV.

[0015] As a preferred technical solution of the present application: the output voltage level of the second diesel generator is 10kV.

[0016] As a preferred technical solution of the present application: the 400V power center is provided with at least two.

[0017] The second object of the present application is to provide a large-capacity offshore converter station station power control method.

[0018] To this end, the above-mentioned object of the present application is achieved by the following technical solutions:

[0019] A large-capacity offshore converter station station power control method, the control method is based on the large-capacity offshore converter station station power system described above, including 10kV high-voltage station power system and power center two parts:

[0020] The control method of 10kV high-voltage station power system includes:

[0021] When the first high-voltage step-down transformer and the second high-voltage step-down transformer are normal, the first 10kV incoming line circuit breaker and the second 10kV incoming line circuit breaker are closed, the first 10kV contactor and the second 10kV contactor are opened, the first 10kV working section and the second 10kV working section are operated in parallel, the first high-voltage step-down transformer and the second high-voltage step-down transformer supply power to the first 10kV working section and the second 10kV working section respectively, and the first diesel generator and the second diesel generator are not started;

[0022] When the first high-voltage step-down transformer is faulty or under maintenance and the second high-voltage step-down transformer is normal, the first 10kV incoming line circuit breaker is opened, the second 10kV incoming line circuit breaker is closed, the first 10kV contactor and the second 10kV contactor are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, the second high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and the first diesel generator and the second diesel generator are not started;

[0023] When the first high-voltage step-down transformer is normal and the second high-voltage step-down transformer is faulty or under maintenance, the first 10kV incoming line circuit breaker is closed, the second 10kV incoming line circuit breaker is opened, the first 10kV contactor and the second 10kV contactor are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, the first high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and the first diesel generator and the second diesel generator are not started;

[0024] When the first high-voltage step-down transformer and the second high-voltage step-down transformer are both faulty or under maintenance or in the black start stage, any one of the first diesel generator and the second diesel generator is started, is connected to the 10kV emergency section through the ATS automatic transfer switch, the first 10kV incoming line circuit breaker and the second 10kV incoming line circuit breaker are opened, the first 10kV tie circuit breaker and the second 10kV tie circuit breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, and the first diesel generator or the second diesel generator supplies power to the first 10kV working section and the second 10kV working section;

[0025] The 400V power center control method comprises:

[0026] When the first station transformer and the second station transformer are normally operated, the first 400V incoming line circuit breaker and the second 400V incoming line circuit breaker are closed, the 400V tie circuit breaker is opened, the first 400V working section and the second 400V working section are operated in parallel, and the first station transformer and the second station transformer supply power to the first 400V working section and the second 400V working section respectively;

[0027] When the first station transformer is faulty or under maintenance and the second station transformer is normally operated, the first 400V incoming line circuit breaker is opened, the second 400V incoming line circuit breaker is closed, the 400V tie circuit breaker is closed, the first 400V working section and the second 400V working section are operated in parallel, and the second station transformer supplies power to the first 400V working section and the second 400V working section;

[0028] When the second station transformer is faulty or under maintenance and the first station transformer is normally operated, the first 400V incoming line circuit breaker is closed, the second 400V incoming line circuit breaker is opened, the 400V tie circuit breaker is closed, the first 400V working section and the second 400V working section are operated in parallel, and the first station transformer supplies power to the first 400V working section and the second 400V working section.

[0029] The application provides a large-capacity offshore converter station power system and a control method, which has the following beneficial effects: two high-voltage working power supplies are arranged, two 10kV high-voltage emergency power generation units are arranged, two 10kV working sections and one 10kV emergency section are arranged, a single-bus three-section 10kV wiring mode is formed, the number of high-voltage power supplies is increased from two to three, and the reliability of the entire station power system is improved; according to the station power load demand of the offshore converter station, a plurality of 400V power centers are arranged, and each power center adopts single-bus sectional wiring; meanwhile, the high-voltage emergency power generation unit reduces the number of outgoing cables, and the outgoing cable of a single diesel generator is reduced from eight 400V power cables in parallel to one 10kV power cable, which is reduced to 12.5% of the original, and no tie switches and tie cables are required between the power centers, which greatly reduces the construction pressure of the cable channel of the offshore converter station, reduces the cost of the cable, and is economical. In addition, the number of power centers can be expanded according to the project requirements, and there is no limiting factor, and the expansibility is good. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The arrangement schematic diagram of the large-capacity offshore converter station power system provided by the application.

[0031] In the figure: 1-first high-voltage step-down transformer; 2-second high-voltage step-down transformer; 3-first 10kV incoming line breaker; 4-second 10kV incoming line breaker; 5-first 10kV working section; 6-second 10kV working section; 7-first diesel generator; 8-second diesel generator; 9-ATS automatic transfer switch; 10-10kV emergency section; 11-first 10kV tie breaker; 12-second 10kV tie breaker; 13-first station transformer; 14-second station transformer; 15-third station transformer; 16-fourth station transformer; 17-fifth station transformer; 18-sixth station transformer; 19-first 400V incoming line breaker; 20-second 400V incoming line breaker; 21-third 400V incoming line breaker; 22-fourth 400V incoming line breaker; 23-fifth 400V incoming line breaker; 24-sixth 400V incoming line breaker; 25-first power center; 26-second power center; 27-third power center; 251-first 400V working section; 252-second 400V working section; 253-first 400V tie breaker; 261-third 400V working section; 262-fourth 400V working section; 263-second 400V tie breaker; 271-fifth 400V working section; 272-sixth 400V working section; 273-third 400V tie breaker. DETAILED DESCRIPTION

[0032] The application will be further described in detail with reference to the drawings and specific examples.

[0033] As Figure 1As shown, a large-capacity offshore converter station power system includes a first high-voltage power supply, a second high-voltage power supply, a first high-voltage step-down transformer 1, a first 10kV incoming line circuit breaker 3, and a first 10kV working section 5 connected to the first high-voltage power supply; a second high-voltage step-down transformer 2, a second 10kV incoming line circuit breaker 4, and a second 10kV working section 6 connected to the second high-voltage power supply;

[0034] A 10kV emergency section 10 is provided between the first 10kV working section 5 and the second 10kV working section 6, and a first diesel generator 7 and a second diesel generator 8 are provided on the 10kV emergency section 10. An ATS automatic transfer switch 9 is provided between the 10kV emergency section 10 and the first diesel generator 7 and the second diesel generator 8. The 10kV emergency section 10 is connected to the first 10kV working section 5 and the second 10kV working section 6 through a first 10kV tie circuit breaker 11 and a second 10kV tie circuit breaker 12.

[0035] A plurality of 400V power centers are provided between the first 10kV working section 5 and the second 10kV working section 6. Two 10kV working power supplies of each power center are respectively led from the first 10kV working section 5 and the second 10kV working section 6. Each 10kV working power supply is stepped down to 400V through a first station transformer and a second station transformer. A first 400V incoming line circuit breaker and a second 400V incoming line circuit breaker are respectively connected to a first 400V working section and a second 400V working section of the power center. A 400V tie circuit breaker is provided between the first 400V working section and the second 400V working section.

[0036] The high-voltage side voltage level of the first high-voltage step-down transformer 1 and the second high-voltage step-down transformer 2 is matched with the offshore converter station, including 35kV, 66kV, 110kV, 220kV and other voltage levels, which are stepped down to 10kV through step-down transformers and connected to 10kV working sections. The capacity of any one high-voltage step-down transformer needs to meet the total station power load under the normal operating condition of the offshore converter station.

[0037] The output voltage level of the first diesel generator 7 and the second diesel generator 8 is 10kV. The two diesel generators have the same capacity and adopt a one active and one standby mode. Any one diesel generator needs to meet the total station power load under the black start, maintenance and emergency conditions of the offshore converter station. Only one diesel generator is connected to the 10kV emergency section at the same time. The two diesel generators can be alternately connected to improve the utilization rate of equipment.

[0038] The 400V power center has at least two.

[0039] A large-capacity offshore converter station power control method includes a 10kV high-voltage station power system and a power center:

[0040] 10kV high-voltage station power system control method comprises:

[0041] When the first high-voltage step-down transformer and the second high-voltage step-down transformer are normally operated, the first 10kV incoming line circuit breaker and the second 10kV incoming line circuit breaker are closed, the first 10kV contact breaker and the second 10kV contact breaker are opened, the first 10kV working section and the second 10kV working section are operated in parallel, the first high-voltage step-down transformer and the second high-voltage step-down transformer supply power to the first 10kV working section and the second 10kV working section respectively, and the first diesel generator and the second diesel generator are not started;

[0042] When the first high-voltage step-down transformer is faulty or under maintenance and the second high-voltage step-down transformer is normally operated, the first 10kV incoming line circuit breaker is opened, the second 10kV incoming line circuit breaker is closed, the first 10kV contact breaker and the second 10kV contact breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, the second high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and the first diesel generator and the second diesel generator are not started;

[0043] When the first high-voltage step-down transformer is normally operated and the second high-voltage step-down transformer is faulty or under maintenance, the first 10kV incoming line circuit breaker is closed, the second 10kV incoming line circuit breaker is opened, the first 10kV contact breaker and the second 10kV contact breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, the first high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and the first diesel generator and the second diesel generator are not started;

[0044] When the first high-voltage step-down transformer and the second high-voltage step-down transformer are both faulty or under maintenance or in the black start stage, any one of the first diesel generator and the second diesel generator is started, connected to the 10kV emergency section through the ATS automatic transfer switch, the first 10kV incoming line circuit breaker and the second 10kV incoming line circuit breaker are opened, the first 10kV contact breaker and the second 10kV contact breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section are operated in parallel, and the first diesel generator or the second diesel generator supplies power to the first 10kV working section and the second 10kV working section;

[0045] 400V power center control method comprises:

[0046] When the first station transformer and the second station transformer are in normal operation, the first 400V incoming line circuit breaker and the second 400V incoming line circuit breaker are closed, the 400V tie circuit breaker is opened, the first 400V working section and the second 400V working section are in parallel operation, and the first station transformer and the second station transformer supply power to the first 400V working section and the second 400V working section respectively.

[0047] When the first station transformer is in fault or maintenance and the second station transformer is in normal operation, the first 400V incoming line circuit breaker is opened, the second 400V incoming line circuit breaker is closed, the 400V tie circuit breaker is closed, the first 400V working section and the second 400V working section are in parallel operation, and the second station transformer supplies power to the first 400V working section and the second 400V working section.

[0048] When the second station transformer is in fault or maintenance and the first station transformer is in normal operation, the first 400V incoming line circuit breaker is closed, the second 400V incoming line circuit breaker is opened, the 400V tie circuit breaker is closed, the first 400V working section and the second 400V working section are in parallel operation, and the first station transformer supplies power to the first 400V working section and the second 400V working section.

[0049] Specifically, the above-mentioned large-capacity offshore converter station power system is implemented by the following manner:

[0050] In the embodiment, considering the high power load of the 2000MW-scale offshore converter station, three 400V power centers are arranged to realize power supply for the whole station power load.

[0051] The two 10kV working power sources of the first power center 25 are respectively introduced from the first 10kV working section 5 and the second 10kV working section 6, are stepped down to 400V by the first station transformer 13 of the first power center and the fourth station transformer 16 of the second power center, are respectively connected to the first 400V working section 251 and the second 400V working section 252 of the first power center 25 by the first 400V incoming line circuit breaker 19 of the first power center and the fourth 400V incoming line circuit breaker 22 of the first power center, and the first 400V working section 251 and the second 400V working section 252 are connected by the first 400V tie circuit breaker to form a single-bus sectional wiring.

[0052] The two 10kV working power sources of the second power center 26 are respectively introduced from the first 10kV working section 5 and the second 10kV working section 6, are stepped down to 400V through the second station transformer 14 of the second power center 26 and the fifth station transformer 17 of the second power center 26, are respectively connected to the third 400V working section 261 and the fourth 400V working section 262 of the second power center 26 through the second 400V incoming line circuit breaker 20 of the second power center 26 and the fifth 400V incoming line circuit breaker 23 of the second power center 26, and the third 400V working section 261 and the fourth 400V working section 262 are connected through the second 400V tie circuit breaker 263 to form a single-bus sectional wiring.

[0053] The two 10kV working power sources of the third power center 27 are respectively introduced from the first 10kV working section 5 and the second 10kV working section 6, are stepped down to 400V through the third station transformer 15 of the third power center and the sixth station transformer 18 of the third power center, are respectively connected to the fifth 400V working section 271 and the sixth 400V working section 272 of the third power center 27 through the third 400V incoming line circuit breaker 21 of the third power center and the sixth 400V incoming line circuit breaker 24 of the third power center, and the fifth 400V working section 271 and the sixth 400V working section 272 are connected through the third 400V tie circuit breaker 273 to form a single-bus sectional wiring.

[0054] The three power centers can be arranged at the place where the power load of the offshore converter station is concentrated, so as to supply power nearby, reduce the length of 400V cable, reduce the voltage drop, reduce the loss, and improve the economy of the project.

[0055] In the embodiment, the 10kV high-voltage station power system includes the following operation modes:

[0056] a) The first high-voltage step-down transformer 1 and the second high-voltage step-down transformer 2 are normally operated. The first 10kV incoming line circuit breaker 3 and the second 10kV incoming line circuit breaker 4 are closed, and the first 10kV tie circuit breaker 11 and the second 10kV tie circuit breaker 12 are opened. The first 10kV working section 5 and the second 10kV working section 6 are operated in parallel, the first high-voltage step-down transformer 1 and the second high-voltage step-down transformer 2 supply power to the first 10kV working section 5 and the second 10kV working section 6 respectively, and the first diesel generator 7 and the second diesel generator 8 are not started.

[0057] b) The first high-voltage step-down transformer 1 fails or is under maintenance, and the second high-voltage step-down transformer 2 is in normal operation. The first 10kV incoming line circuit breaker 3 is tripped, the second 10kV incoming line circuit breaker 4 is closed, and the first 10kV tie circuit breaker 11 and the second 10kV tie circuit breaker 12 are closed. The first 10kV working section 5, the second 10kV working section 6, and the 10kV emergency section 10 are in parallel operation, the second high-voltage step-down transformer 2 supplies power to the first 10kV working section 5 and the second 10kV working section 6, and the first diesel generator 7 and the second diesel generator 8 are not started.

[0058] c) The first high-voltage step-down transformer 1 is in normal operation, and the second high-voltage step-down transformer 2 fails or is under maintenance. The first 10kV incoming line circuit breaker 3 is closed, the second 10kV incoming line circuit breaker 4 is tripped, and the first 10kV tie circuit breaker 11 and the second 10kV tie circuit breaker 12 are closed. The first 10kV working section 5, the second 10kV working section 6, and the 10kV emergency section 10 are in parallel operation, the first high-voltage step-down transformer 1 supplies power to the first 10kV working section 5 and the second 10kV working section 6, and the first diesel generator 7 and the second diesel generator 8 are not started.

[0059] d) Both the first high-voltage step-down transformer 1 and the second high-voltage step-down transformer 2 fail or are under maintenance or in the black start phase. Start any one of the first diesel generator 7 and the second diesel generator 8, and connect it to the 10kV emergency section 10 through the ATS automatic transfer switch 9. The first 10kV incoming line circuit breaker 3 and the second 10kV incoming line circuit breaker 4 are tripped, the first 10kV tie circuit breaker 11 and the second 10kV tie circuit breaker 12 are closed. The first 10kV working section 5, the second 10kV working section 6, and the 10kV emergency section 10 are in parallel operation, and the first diesel generator 7 or the second diesel generator 8 supplies power to the first 10kV working section 5 and the second 10kV working section 6.

[0060] In this embodiment, the first 400V power center includes the following operation modes (the second 400V power center and the third 400V power center have the same operation modes):

[0061] a) The first station transformer 13 and the fourth station transformer 16 are in normal operation. The first 400V incoming line circuit breaker 19 and the fourth 400V incoming line circuit breaker 22 are closed, and the first 400V tie circuit breaker 253 is tripped. The first 400V working section and the second 400V working section 252 are in separate operation, and the first station transformer 13 and the fourth station transformer 16 supply power to the first 400V working section and the second 400V working section 252, respectively.

[0062] b) The first station transformer 13 is faulty or under repair, and the fourth station transformer 16 is in normal operation. The first 400V incoming line circuit breaker 19 is open, the fourth 400V incoming line circuit breaker 22 is closed, and the first 400V tie circuit breaker 25 is closed. The first 400V operating section and the second 400V operating section 252 are in parallel operation, and the fourth station transformer 16 supplies power to the first 400V operating section and the second 400V operating section 252.

[0063] c) The fourth station transformer 16 is faulty or under repair, and the first station transformer 13 is in normal operation. The first 400V incoming line circuit breaker 19 is closed, the fourth 400V incoming line circuit breaker 22 is open, and the first 400V tie circuit breaker 25 is closed. The first 400V operating section and the second 400V operating section 252 are in parallel operation, and the first station transformer 13 supplies power to the first 400V operating section and the second 400V operating section 252.

[0064] The above detailed description is used to explain and illustrate the present application, and is only a preferred embodiment of the present application, but not a limitation on the present application. Any modification, equivalent replacement, improvement, etc. made to the present application within the spirit of the present application and the protection scope of the claims, falls into the protection scope of the present application.

Claims

1. A high-capacity offshore converter station power supply system, comprising a first high-voltage working power supply and a second high-voltage working power supply, characterized in that: The first high-voltage working power supply is equipped with a first high-voltage step-down transformer (1), a first 10kV incoming circuit breaker (3) and connected to the first 10kV working section (5). The second high-voltage working power supply is equipped with a second high-voltage step-down transformer (2), a second 10kV incoming circuit breaker (4) and connected to the second 10kV working section (6). A 10kV emergency section (10) is provided between the first 10kV working section (5) and the second 10kV working section (6). A first diesel generator (7) and a second diesel generator (8) are provided on the 10kV emergency section (10). An ATS automatic transfer switch (9) is provided between the 10kV emergency section (10) and the first diesel generator (7) and the second diesel generator (8). The 10kV emergency section (10) is connected to the first 10kV working section (5) and the second 10kV working section (6) through a first 10kV tie circuit breaker (11) and a second 10kV tie circuit breaker (12), respectively. Multiple 400V power centers are provided between the first 10kV working section (5) and the second 10kV working section (6). The two 10kV working power supplies of each power center are respectively drawn from the first 10kV working section (5) and the second 10kV working section (6). Each 10kV working power supply is stepped down to 400V through the first station transformer and the second station transformer, and connected to the first 400V working section and the second 400V working section of the power center through the first 400V incoming line circuit breaker and the second 400V incoming line circuit breaker, respectively. A 400V tie circuit breaker is provided between the first 400V working section and the second 400V working section.

2. The power supply system for a large-capacity offshore converter station according to claim 1, characterized in that: The high voltage side voltage level of the first high voltage step-down transformer (1) is matched with the offshore converter station, including multiple voltage levels of 35kV, 66kV, 110kV and 220kV.

3. The power supply system for a large-capacity offshore converter station according to claim 1, characterized in that: The high-voltage side voltage level of the second high-voltage step-down transformer (2) is matched with the offshore converter station, including multiple voltage levels of 35kV, 66kV, 110kV and 220kV.

4. The power supply system for a large-capacity offshore converter station according to claim 1, characterized in that: The first diesel generator (7) has an output voltage rating of 10kV.

5. The power supply system for a large-capacity offshore converter station according to claim 1, characterized in that: The output voltage level of the second diesel generator (8) is 10kV.

6. The power supply system for a large-capacity offshore converter station according to claim 1, characterized in that: At least two 400V power centers are provided.

7. A power control method for a large-capacity offshore converter station, characterized in that: The control method is based on the high-capacity offshore converter station power supply system as described in any one of claims 1-6, comprising two parts: a 10kV high-voltage station power supply system and a power center. The control methods for the power supply system of a 10kV high-voltage substation include: When the first high-voltage step-down transformer and the second high-voltage step-down transformer are operating normally, the first 10kV incoming line circuit breaker and the second 10kV incoming line circuit breaker are closed, the first 10kV tie circuit breaker and the second 10kV tie circuit breaker are open, the first 10kV working section and the second 10kV working section are operating separately, the first high-voltage step-down transformer and the second high-voltage step-down transformer supply power to the first 10kV working section and the second 10kV working section respectively, and neither the first diesel generator nor the second diesel generator is started. When the first high-voltage step-down transformer fails or is under maintenance, and the second high-voltage step-down transformer is operating normally, the first 10kV incoming circuit breaker is open, the second 10kV incoming circuit breaker is closed, the first 10kV tie circuit breaker and the second 10kV tie circuit breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section operate in parallel, the second high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and neither the first diesel generator nor the second diesel generator starts; When the first high-voltage step-down transformer is operating normally, and the second high-voltage step-down transformer is faulty or under maintenance, the first 10kV incoming circuit breaker is closed, the second 10kV incoming circuit breaker is open, the first 10kV tie circuit breaker and the second 10kV tie circuit breaker are closed, the first 10kV working section, the second 10kV working section and the 10kV emergency section operate in parallel, the first high-voltage step-down transformer supplies power to the first 10kV working section and the second 10kV working section, and neither the first diesel generator nor the second diesel generator starts; When both the first and second high-voltage step-down transformers are faulty, under maintenance, or in the black start phase, either the first or second diesel generator starts and connects to the 10kV emergency section via the ATS automatic transfer switch. The first and second 10kV incoming circuit breakers open, and the first and second 10kV tie circuit breakers close. The first 10kV working section, the second 10kV working section, and the 10kV emergency section operate in parallel, and either the first or second diesel generator supplies power to the first and second 10kV working sections. The control methods for a 400V power center include: When the first and second substations are operating normally, the first 400V incoming circuit breaker and the second 400V incoming circuit breaker are closed, the 400V tie circuit breaker is open, the first 400V working section and the second 400V working section are operated separately, and the first and second substations supply power to the first 400V working section and the second 400V working section respectively. When the first substation transformer fails or is under maintenance, and the second substation transformer is operating normally, the first 400V incoming line circuit breaker opens, the second 400V incoming line circuit breaker closes, the 400V tie circuit breaker closes, the first 400V working section and the second 400V working section operate in parallel, and the second substation transformer supplies power to the first 400V working section and the second 400V working section. When the second substation transformer fails or is under maintenance, and the first substation transformer is operating normally, the first 400V incoming line circuit breaker closes, the second 400V incoming line circuit breaker opens, the 400V tie circuit breaker closes, the first 400V working section and the second 400V working section operate in parallel, and the first substation transformer supplies power to the first 400V working section and the second 400V working section.

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