CN218242573U - An electrical main wiring structure suitable for a single main transformer small offshore booster station - Google Patents

Abstract

The utility model provides an electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer, including a group of main transformer units, a group of 220kV power distribution device units, a first group of switch cabinet units, and a second group of switch cabinets unit and station power unit; the high-voltage side of the main transformer unit is connected to the 220kV power distribution unit; connection; the first incoming line and the second incoming line of the station power unit are respectively connected to the first group of switch cabinet units and the second group of switch cabinet units, and the third incoming line of the station power unit is connected to the diesel generator machine connection. The utility model simplifies the wiring mode of the offshore booster station without affecting the existing functions of the offshore booster station, reduces the number of required equipment, and helps to realize the compact arrangement of the offshore booster station and the overall size of the booster station And weight optimization, reduce the construction cost of offshore booster stations, and improve the investment benefits of offshore wind power projects.

Description

An electrical main wiring structure suitable for a single main transformer small offshore booster station

technical field

The utility model relates to the field of offshore wind power generation, in particular to an electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer.

Background technique

In recent years, with the continuous development of economy and society, my country's energy demand will continue to grow. Increasing energy supply, ensuring energy security, protecting the ecological environment, and promoting sustainable economic and social development are a major strategic task for my country's economic and social development.

With the advancement of offshore wind power technology and the reduction of cost, its global market scale is expanding rapidly. As of the end of 2020, my country's grid-connected offshore wind power capacity has reached approximately 8.99 million kW, ranking among the top three in the world, and its new offshore wind power installed capacity has ranked first in the world for two consecutive years.

At the same time, with the advent of the era of offshore wind power subsidy and parity after 2021, offshore wind power is also facing greater pressure in terms of investment and operation and maintenance costs. How to relieve cost pressure and tap the potential for cost reduction is the key to improving the future competitiveness of offshore wind power. determinant of power. As an important part of offshore wind power projects, offshore booster stations should also explore more competitive offshore booster station solutions to meet the needs of offshore wind power development in the new era.

The investment and construction cost of the offshore booster station mainly comes from the equipment cost and construction cost. At present, the traditional offshore booster station is equipped with two main transformers, correspondingly equipped with more complicated power distribution devices and auxiliary systems, resulting in the structure of the booster station Complexity, heavy weight, high construction difficulty, and high investment and construction costs. Under the requirements of cost reduction and efficiency increase in the era of offshore wind power parity, it is of great significance to explore a new type of electrical main wiring that meets the transmission needs of small offshore wind farms and simplifies offshore booster station equipment. This will help realize the compact arrangement of small offshore booster stations and optimize the overall size and weight of the booster station, further reduce the investment and construction costs of offshore booster stations, and improve the investment benefits of offshore wind power projects.

Utility model content

Aiming at the deficiencies in the prior art, the purpose of this utility model is to provide an electrical main wiring structure suitable for a single main transformer small-scale offshore step-up station. The utility model simplifies the wiring mode of the offshore booster station without affecting the existing functions of the offshore booster station, reduces the number of required equipment, and helps to realize the compact arrangement of the offshore booster station and the overall size of the booster station And weight optimization, reduce the construction cost of offshore booster stations, and improve the investment benefits of offshore wind power projects.

In order to solve the above technical problems, the utility model is realized through the following technical solutions:

An electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer, characterized in that it includes a group of main transformer units, a group of 220kV power distribution device units, a first group of switch cabinet units, and a second group of switch cabinet units And the station power unit; the high voltage side of the main transformer unit is connected to the 220kV power distribution device unit; the two incoming lines of the low voltage side of the main transformer unit are respectively connected to the first group of switch cabinet units and the second group of switch cabinet units ; The first incoming line and the second incoming line of the station power unit are respectively connected to the first group of switch cabinet units and the second group of switch cabinet units, and the third incoming line of the station power unit is connected to the diesel generator connect.

Further: the main transformation unit includes a main transformer, and the main transformer is a three-phase three-winding transformer connected in star-delta-delta connection.

Further: the 220kV power distribution device unit is a group of 220kV GIS, the incoming line side of the 220kV GIS is connected to the high voltage side of the main transformer, and the outgoing line side is connected to the 220kV submarine cable.

Further: the first group of switchgear units includes 8 SF6 insulated high-voltage switchgears; wherein,

The 6-side SF6 insulated high-voltage switchgear is the first fan incoming line cabinet, one SF6-insulated high-voltage switchgear is the grounding transformer and station transformer incoming line cabinet, and one SF6-insulated high-voltage switchgear is the main transformer outgoing line cabinet;

The inlet side of the fan inlet cabinet 1 is connected to the wind farm collector submarine cable, and the outlet side of the fan inlet cabinet 1 is connected to the first section of the 35kV busbar;

The incoming line side of the grounded substation and substation-use variable incoming line cabinet is connected to the first section of 35kV busbar, and the outgoing line side of the grounded substation and substation-used variable incoming line cabinet is connected to the station power unit;

The incoming line side of the main transformer outgoing line cabinet is connected to the first section of 35kV busbar, and the outgoing line side of the main transformer outgoing line cabinet is connected to the main transformer unit.

Further: the second group of switchgear units includes 8 SF6 insulated high-voltage switchgears; wherein,

The 6-side SF6 insulated high-voltage switchgear is the second fan incoming line cabinet, one SF6-insulated high-voltage switchgear is the grounding transformer and station transformer incoming line cabinet, and one SF6-insulated high-voltage switchgear is the main transformer outgoing line cabinet;

The inlet side of the fan inlet cabinet 2 is connected to the wind farm collector submarine cable, and the outlet side is connected to the second section of the 35kV busbar;

The incoming line side of the grounding substation and substation substation incoming cabinet is connected to the second section of 35kV busbar, and the outgoing line side is connected to the station power unit;

The incoming line side of the main transformer outlet cabinet is connected to the second 35kV busbar, and the outgoing line side is connected to the main transformer unit.

Further: the station power unit includes a first grounding transformer and station transformer, a second grounding transformer and station transformer, a diesel generator and a low-voltage power distribution bus, and the low-voltage power distribution bus includes the first section of low-voltage power distribution bus, The second section of low-voltage power distribution busbar and the third section of low-voltage power distribution busbar; among them,

The high-voltage side of the transformer for the first grounding substation and substation is respectively connected to the first group of switch cabinet units, and the second transformer for grounding substation and substation is connected to the second group of switch cabinet units;

The low-voltage side of the transformer for the first grounding substation and substation is connected to the first section of low-voltage power distribution bus, and the second transformer for grounding substation and substation is connected to the second section of low-voltage power distribution bus;

The third low-voltage power distribution bus is connected to the diesel generator.

Further: the low-voltage side of the transformer for the first grounding substation and substation is connected to the first section of low-voltage power distribution bus through the first circuit breaker; the neutral point of the high-voltage side of the transformer for the first grounding substation and substation is connected through the first grounding resistor Grounding; the low-voltage side of the transformer for the second grounding substation and substation is connected to the second section of low-voltage power distribution bus through the second circuit breaker, and the neutral point of the high-voltage side of the transformer for the second grounding substation and substation is grounded through the second grounding resistor .

Further: the diesel generator is connected to the third low-voltage distribution bus through the third circuit breaker; the first low-voltage distribution bus is connected to the second low-voltage distribution bus through the fifth circuit breaker; the first low-voltage distribution The electric bus is connected to the third low-voltage distribution bus through the fourth circuit breaker 554 and the eighth circuit breaker; the second low-voltage distribution bus is connected to the third low-voltage distribution bus through the sixth circuit breaker and the seventh circuit breaker.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. The utility model adopts the wiring of a 220kV line transformer group, which has the advantages of simple structure, less investment, less land occupation, and good economic benefits. The station power unit of the utility model adopts three sections of low-voltage power distribution buses, wherein, the low-voltage side of the first grounding substation and station transformer is connected to the first section of low-voltage power distribution bus, and the second grounding substation and station transformer is connected to the second The first section of low-voltage power distribution bus is connected; the third section of low-voltage power distribution bus is connected with diesel generators, which improves the reliability of power consumption of the station.

2. The electrical main wiring described in the utility model is helpful to realize the compact layout of offshore small offshore booster stations and the optimization of the overall size and weight of the booster stations, further reduce the investment and construction costs of offshore booster stations, and improve the efficiency of offshore wind power projects. investment benefits.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the structural representation of main transformer unit of the present utility model;

Fig. 3 is a structural schematic diagram of a 220kV power distribution device unit of the present invention;

Fig. 4 is a schematic structural view of the first group of switch cabinet units of the utility model;

Fig. 5 is a schematic structural view of the second group of switch cabinet units of the present invention;

Fig. 6 is a schematic structural view of the station power unit of the present invention.

detailed description

In order to enable those skilled in the art to better understand the technical solutions of the present utility model, the preferred embodiments of the present utility model are described below in conjunction with specific examples, but it should be understood that the accompanying drawings are only for illustrative purposes and cannot be interpreted as a description of the present invention. Limitation of utility models; in order to better illustrate this embodiment, some parts in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, some known structures and It is understandable that its description may be omitted. The positional relationship described in the drawings is for illustrative purposes only, and should not be construed as a limitation of the present utility model.

The utility model will be further described below in conjunction with the accompanying drawings and embodiments, but it is not used as a basis for limiting the utility model.

As shown in Figures 1 to 6, an electrical main wiring structure suitable for a small offshore booster station with a single main transformer includes a set of main transformer units 100, a set of 220kV power distribution device units 200, and a first set of switch cabinet units 300 , the second group of switchgear units 400 and the station power unit 500; the high voltage side of the main transformer unit 100 is connected to the 220kV power distribution device unit 200; the two incoming lines of the low voltage side of the main transformer unit 100 are connected to the first The group switch cabinet unit 300 is connected to the second group switch cabinet unit 400; the first return incoming line and the second return incoming line of the station power unit 500 are respectively connected to the first group switch cabinet unit 300 and the second group switch cabinet unit 400 The third incoming line of the station power unit 500 is connected to the diesel generator 531 .

The main transformation unit 100 includes a main transformer 111, which is a three-phase three-winding transformer connected in star-delta-delta connection.

The main transformer 111 is provided with a first main transformer current transformer 112 on the high voltage side; the main transformer 111 is provided with a second main transformer current transformer 113 on the high voltage neutral point side.

The 220kV power distribution device unit 200 is a group of 220kV GIS, 220kV is the voltage level, and the GIS is a sulfur hexafluoride gas-insulated fully enclosed power distribution device. The incoming line side of the 220kV GIS is connected to the high voltage side of the main transformer 111, and the outgoing line side is connected to 220kV submarine cable connection. The electrical equipment in the 220kV GIS is from the high-voltage side of the main transformer 111 to the 220kV submarine cable, in order the first arrester 271, the first grounding switch 231, the first isolation switch 221, the second grounding switch 232, the first current transformer 261, and the 220kV distribution The circuit breaker 211, the second current transformer 262, the third earthing switch 233, the second isolating switch 222, the fast earthing switch 241, the voltage transformer 251 and the second lightning arrester 272 of the electrical device unit; wherein, the first isolating switch 221 and The second isolating switch 222, the first current transformer 261 and the second current transformer 262, and the circuit breaker 211 of the 220kV power distribution unit are connected in series to the line, and the rest of the electrical equipment are connected in parallel to the line.

The first group of switch cabinet units 300 includes 8 SF6 insulated high voltage switch cabinets; wherein,

The 6-sided SF6 insulated high-voltage switchgear is the fan inlet cabinet 1 310/320/330/350/360/370, and the 1-sided SF6 insulated high-voltage switchgear is the first unit’s grounding transformer and station transformer inlet cabinet 340, 1 side The SF6 insulated high-voltage switchgear is the main transformer outlet cabinet 380 of the first unit;

The inlet side of the fan inlet cabinet-310/320/330/350/360/370 is connected to the wind farm collector submarine cable, and the outlet side of the fan inlet cabinet-310/320/330/350/360/370 Connect with the first 35kV busbar 390;

The incoming line side of the grounding substation and substation-use variable incoming line cabinet 340 of the first unit is connected to the first section of 35kV busbar 390, and the outgoing line side of the first unit’s grounded substation and substation-use variable incoming line cabinet 340 is connected to the station power Unit 500 connection;

The incoming line side of the main transformer outgoing line cabinet 380 of the first unit is connected to the first section of 35kV busbar 390 , and the outgoing line side of the main transformer outgoing line cabinet 380 of the first unit is connected to the main transformer unit 100 .

The fan inlet cabinet includes the first fan inlet cabinet 310 of the first unit, the second fan inlet cabinet 320 of the first unit, the third fan inlet cabinet 330 of the first unit, and the fifth fan inlet cabinet of the first unit. The fan inlet cabinet 350, the sixth fan inlet cabinet 360 of the first unit, and the seventh fan inlet cabinet 370 of the first unit.

Take the first fan inlet cabinet 310 of the first unit as an example to describe the implementation: the electrical equipment in the switch cabinet of the first fan inlet cabinet 310 of the first unit is from the wind farm power collection submarine cable to the 35kV bus bar 390 in sequence. The zero-sequence current transformer 316 of the first fan inlet cabinet, the lightning arrester 313 of the first fan inlet cabinet, the current transformer 315 of the first fan inlet cabinet, the live display 314 of the first fan inlet cabinet, the first fan inlet The circuit breaker 311 of the line cabinet and the three-position isolating switch 312 of the first fan inlet cabinet. Among the remaining fan inlet cabinets, the electrical equipment arrangement of the second fan inlet cabinet 320 of the first unit, the third fan inlet cabinet 330 of the first unit, and the fifth fan inlet cabinet 350 of the first unit are similar to those of the first unit. The first fan inlet cabinet 310 of the first unit is exactly the same; the sixth fan inlet cabinet 360 of the first unit is compared with the electrical equipment in the first fan inlet cabinet 310 of the first unit, and a 35kV bus arrester 367 is added; The seventh fan inlet cabinet 370 of one unit is compared with the electrical equipment in the first fan inlet cabinet 310 of the first unit, and the two-position isolating switch 377 of the seventh fan inlet cabinet and the seventh fan inlet cabinet are added The bus arrester 378 of the first unit; the arrangement of the electrical equipment in the grounding substation and substation input cabinet 340 of the first unit is exactly the same as that of the electrical equipment in the first fan input cabinet 310 of the first unit; the main transformer outlet cabinet of the first unit The electrical equipment in 380 connects cables from the 35kV bus 390 to the main transformer in sequence: the three-position isolating switch 382 of the main transformer outlet cabinet, the circuit breaker 381 of the main transformer outlet cabinet, the live display 384 of the main transformer outlet cabinet, and the main transformer outlet The current transformer 385 of the cabinet, the lightning arrester 383 of the main transformer outlet cabinet and the zero-sequence current transformer 386 of the main transformer outlet cabinet.

The second group of switch cabinet units 400 includes 8 SF6 insulated high voltage switch cabinets; wherein,

The 6-sided SF6 insulated high-voltage switchgear is the fan inlet cabinet 2 410/420/430/440/450/460, and the 1-sided SF6-insulated high-voltage switchgear is the second unit’s grounding transformer and station-use transformer inlet cabinet 470, 1 side The SF6 insulated high-voltage switchgear is the main transformer outlet cabinet 480 of the second unit;

The inlet side of the fan inlet cabinet 2 410/420/430/440/450/460 is connected to the wind farm collector submarine cable, and the outlet side is connected to the second section of 35kV busbar 490;

The incoming side of the grounding substation and substation substation incoming line cabinet 470 of the second unit is connected to the second section of 35kV busbar 490, and the outgoing side is connected to the station power unit 500;

The incoming line side of the main transformer outlet cabinet 480 of the second unit is connected to the second section of 35kV bus 490 , and the outgoing line side is connected to the main transformer unit 100 .

The fan inlet cabinet includes the first fan inlet cabinet 410 of the second unit, the second fan inlet cabinet 420 of the second unit, the third fan inlet cabinet 430 of the second unit, and the fourth fan inlet cabinet 440 of the second unit , the fifth fan inlet cabinet 450 of the second unit, and the sixth fan inlet cabinet 460 of the second unit.

The electrical equipment arrangement of the first fan inlet cabinet 410 of the second unit, the second fan inlet cabinet 420 of the second unit, the third fan inlet cabinet 430 of the second unit, and the fourth fan inlet cabinet 440 of the second unit are similar to the first The first fan inlet cabinet 310 of the unit is completely consistent; the arrangement of electrical equipment in the fifth fan inlet cabinet 450 of the second unit is consistent with that of the sixth fan inlet cabinet 360 of the first unit; the sixth fan inlet cabinet of the second unit 460 is consistent with the layout of the electrical equipment in the seventh fan inlet cabinet 370 of the first unit; The layout of the electrical equipment is the same; the layout of the electrical equipment in the main transformer outlet cabinet 480 of the second unit is the same as that in the main transformer outlet cabinet 380 of the first unit.

The station power unit 500 includes a first grounding transformer and station transformer 511, a second grounding transformer and station transformer 512, a diesel generator 531, and a low-voltage power distribution bus, and the low-voltage power distribution bus includes the first low-voltage power distribution bus 541. The second low-voltage power distribution bus 542 and the third low-voltage power distribution bus 543; among them,

The high-voltage side of the first grounding transformer and substation transformer 511 is respectively connected to the first group of switch cabinet units 300, and the second grounding substation and substation transformer 512 is connected to the second group of switch cabinet units 400;

The low-voltage side of the transformer 511 for the first grounding substation and substation is connected to the first low-voltage power distribution bus 541, and the second grounding substation and substation transformer 512 is connected to the second low-voltage power distribution bus 542;

The third low-voltage power distribution bus 543 is connected to the diesel generator 531 .

The low-voltage side of the transformer 511 for the first grounding substation and substation is connected to the first section of low-voltage power distribution bus 541 through the first circuit breaker 551; The resistor 521 is grounded; the low-voltage side of the second grounding substation and substation transformer 512 is connected to the second low-voltage power distribution bus 542 through the second circuit breaker 552, and the neutral point of the high-voltage side of the second grounding substation and substation transformer 512 is It is grounded through the second grounding resistor 522 .

The diesel generator 531 is connected to the third low-voltage distribution bus 543 through the third circuit breaker 553; the first low-voltage distribution bus 541 is connected to the second low-voltage distribution bus 542 through the fifth circuit breaker 555; The low-voltage distribution bus 541 of the second section and the low-voltage distribution bus 543 of the third section are connected through the fourth circuit breaker 554 and the eighth circuit breaker 558; 556 and the seventh circuit breaker 557 are connected.

According to the description and accompanying drawings of the utility model, those skilled in the art can easily manufacture or use a kind of electric main wiring structure of the utility model suitable for a single main transformer small-scale offshore step-up station, and can produce the structure described in the utility model. positive effect.

The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any simple modification or equivalent change made to the above embodiments according to the technical essence of the utility model falls within the scope of the present utility model. Within the protection scope of the present utility model.

Claims (8)

1. An electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer, characterized in that it includes a group of main transformer units (100), a group of 220kV power distribution device units (200), a first group of switch cabinets unit (300), the second group of switchgear units (400) and station power unit (500); the high voltage side of the main transformer unit (100) is connected to the 220kV power distribution device unit (200); the main transformer unit (100) the low-voltage side two incoming lines are respectively connected with the first group of switch cabinet units (300) and the second group of switch cabinet units (400); the first incoming line of the station power unit (500) and the second The return incoming line is respectively connected to the first group of switch cabinet units (300) and the second group of switch cabinet units (400), and the third return incoming line of the station power unit (500) is connected to the diesel generator (531). 2. The electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer according to claim 1, characterized in that: the main transformer unit (100) includes a main transformer (111), and the main transformer (111) is a star-delta-delta connection three-phase three-winding transformer. 3. A kind of electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer according to claim 2, characterized in that: the 220kV power distribution device unit (200) is a group of 220kV GIS, 220kV GIS The incoming line side is connected to the high voltage side of the main transformer (111), and the outgoing line side is connected to the 220kV submarine cable. 4. The electrical main wiring structure suitable for a small offshore step-up station with a single main transformer according to claim 1, characterized in that: the first group of switch cabinet units (300) includes 8 SF6 insulated high-voltage switch cabinets ;in, The 6-side SF6 insulated high-voltage switchgear is the fan inlet cabinet (310/320/330/350/360/370), and the 1-side SF6 insulated high-voltage switchgear is the first unit’s grounding transformer and station transformer inlet cabinet (340 ), one SF6 insulated high-voltage switchgear is the main transformer outgoing line cabinet (380) of the first unit; The inlet side of the fan inlet cabinet one (310/320/330/350/360/370) is connected to the wind farm collector submarine cable, and the fan inlet cabinet one (310/320/330/350/360/370 ) is connected to the first 35kV busbar (390); The incoming line side of the grounding transformer and substation of the first unit is connected to the first section of the 35kV busbar (390), and the grounding and substation of the first unit is connected to the incoming line cabinet (340). The outlet side is connected to the station power unit (500); The incoming line side of the main transformer outgoing line cabinet (380) of the first unit is connected to the first section of 35kV busbar (390), and the outgoing line side of the main transformer outgoing line cabinet (380) of the first unit is connected to the main transformer unit (100) . 5. The electrical main wiring structure suitable for a small-scale offshore step-up station with a single main transformer according to claim 1, characterized in that: the second group of switch cabinet units (400) includes 8 SF6 insulated high-voltage switch cabinets ;in, The 6-side SF6 insulated high-voltage switchgear is the second fan inlet cabinet (410/420/430/440/450/460), and the 1-side SF6 insulated high-voltage switchgear is the second unit’s grounding transformer and station transformer inlet cabinet (470 ), one SF6 insulated high-voltage switchgear is the main transformer outlet cabinet of the second unit (480); The inlet side of the fan inlet cabinet 2 (410/420/430/440/450/460) is connected to the wind farm collector submarine cable, and the outlet side is connected to the second section of the 35kV busbar (490); The incoming line side of the grounding transformer and substation transformer inlet cabinet (470) of the second unit is connected to the second section of the 35kV busbar (490), and the outgoing line side is connected to the station power unit (500); The incoming line side of the main transformer outlet cabinet (480) of the second unit is connected to the second section of 35kV busbar (490), and the outgoing line side is connected to the main transformer unit (100). 6. An electrical main wiring structure suitable for a small offshore step-up station with a single main transformer according to claim 1, characterized in that: the station power unit (500) includes a first grounding substation and station transformer ( 511), the second grounding transformer and substation transformer (512), diesel generator (531) and low-voltage power distribution busbar, the low-voltage power distribution busbar includes the first low-voltage power distribution busbar (541), the second low-voltage power distribution busbar (542) and the third low-voltage power distribution busbar (543); wherein, The high-voltage side of the first grounding substation-cum-station transformer (511) is respectively connected to the first group of switch cabinet units (300), and the second grounding substation-cum-station transformer (512) is connected to the second group of switch cabinet units (400) connect; The low-voltage side of the first grounding substation-cum-station transformer (511) is connected to the first low-voltage power distribution busbar (541), and the second grounding substation-cum-station transformer (512) is connected to the second low-voltage power distribution busbar (542). )connect; The third low-voltage power distribution busbar (543) is connected to the diesel generator (531). 7. The electrical main wiring structure suitable for a small offshore step-up substation with a single main transformer according to claim 6, characterized in that: the low-voltage side of the first grounded substation and substation transformer (511) passes through the first The circuit breaker (551) is connected to the first low-voltage power distribution bus (541); the neutral point of the high-voltage side of the first grounding substation and substation transformer (511) is grounded through the first grounding resistor (521); the second grounding The low-voltage side of the transformer (512) for substation and substation is connected to the second section of low-voltage power distribution busbar (542) through the second circuit breaker (552), and the neutral point of the high-voltage side of the transformer (512) for the second grounding substation and substation is connected through the second circuit breaker (552). The second grounding resistor (522) is grounded. 8. The electrical main wiring structure suitable for a small offshore booster station with a single main transformer according to claim 6, characterized in that: the diesel generator (531) is connected to the third circuit breaker (553) via the third circuit breaker (553) The first low-voltage distribution bus (541) is connected to the second low-voltage distribution bus (542) through the fifth circuit breaker (555); the first low-voltage distribution bus (541 ) is connected to the third low-voltage power distribution bus (543) through the fourth circuit breaker 554 and the eighth circuit breaker (558); the second low-voltage power distribution bus (542) is connected to the third low-voltage power distribution bus (543) through The sixth circuit breaker (556) and the seventh circuit breaker (557) are connected.

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