CN209233559U - A kind of station station-service direct current system based on MMC - Google Patents

Abstract

The utility model discloses an MMC-based DC system for stations and factories, which includes a rectification part and an inverter part, wherein the rectification part includes a storage battery, an MMC type rectifier, a fuse, and a disconnector, and the inverter part includes an MMC type inverter, breaker. MMC type rectifier provides AC power from two sections of AC bus. MMC type rectifier is used to convert AC power into DC power, support DC bus voltage, and supply power for station/factory DC loads. The battery is connected to the DC bus through fuses and isolating switches. ; The MMC inverter is connected to the DC bus. The utility model can ensure the power quality of the direct current power supply under the condition that no filter link is needed, and can provide a three-phase alternating current power supply that guarantees the power quality.

Description

A DC system for station and plant based on MMC

technical field

The utility model relates to a direct current system, in particular to an MMC-based direct current system for stations and plants, and belongs to the technical field of power transmission and transformation applications.

Background technique

Station/factory DC system is a power supply system used in substations, converter stations, and power plants to provide DC power for protection, automatic devices, emergency lighting, emergency power supplies, and circuit breaker opening and closing operations. It is used in stations/factories When the AC system fails, the backup power supply—the battery continues to provide DC power, and at the same time provides DC power for the uninterruptible power supply UPS. Therefore, the station/factory DC system plays a vital role in the safe and stable operation of substations, converter stations, and power plants.

At present, DC systems for stations/factories mainly use traditional three-phase three-leg rectifiers as chargers, and UPS composed of single-phase inverters. The power quality of input AC power affects the quality of output DC power, and UPS can only provide single-phase Therefore, to solve the above problems, a MMC-based DC system for stations and factories is proposed.

Utility model content

The purpose of this utility model is to provide a DC system based on MMC to solve the above problems, which can ensure the power quality of DC power supply without the need for filtering links, and provide a three-phase AC power supply to ensure power quality.

The utility model achieves the above object through the following technical solutions, a DC system for station and plant based on MMC, including a rectification part and an inverter part, wherein the rectification part includes a battery, an MMC type rectifier, a fuse and an isolating switch, The output terminal of the battery is connected in series with the input terminal of the fuse, and the output terminal of the fuse is connected in series with the input terminal of the isolating switch;

The inverter part includes an MMC type inverter and a circuit breaker, and the MMC type rectifier is connected through two sections of AC busbars, the AC busbars are the first section of AC and the second section of AC; the output end of the isolating switch and the output end of the circuit breaker It is connected to a section of DC bus, and the section of DC bus is connected to the second section of DC bus through an MMC rectifier.

Preferably, the first AC stage and the second AC stage are connected in series to the MMC rectifier.

Preferably, the section of DC bus is connected to the controller, the protector and the power distribution screens of each level through circuit breakers respectively.

Preferably, the power distribution screens of each level include one of a feed screen, a main charging screen, a backup charging screen, and a battery screen.

The beneficial effects of the utility model are: the MMC type rectifier of the utility model is provided with AC power by two sections of AC busbars, and the MMC type rectifier is used to convert the AC power supply into a DC power supply, support the DC busbar voltage, and supply power for the DC load of the station/factory , the storage battery is connected to the DC bus through fuses and isolating switches; the MMC inverter is connected to the DC bus. The utility model can ensure the power quality of DC power supply without filtering link, and provide a three-phase AC power supply with guaranteed power quality, has good economic and social benefits, and is suitable for popularization and use.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the utility model.

In the figure: 1, storage battery, 2, AC section 1, 3, AC section 2, 4, fuse, 5, isolating switch, 6, DC bus section 7, MMC type rectifier, 8, circuit breaker, 9, MMC type inverter Transformer, 10, two-stage DC bus, 11, controller, 12, protector, 13, electric screens for each grade.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to Fig. 1, a DC system for station and plant based on MMC includes a rectification part and an inverter part, wherein the rectification part includes a storage battery 1, an MMC type rectifier 7, a fuse 4 and an isolating switch 5. The output end of the storage battery 1 is connected in series with the input end of the fuse 4, and the output end of the fuse 4 is connected in series with the input end of the isolating switch 5; the inverter part includes an MMC type inverter 9 and a circuit breaker 8. The MMC type rectifier 7 is connected through two sections of AC busbars, the AC busbars are the first section of AC 2 and the second section of AC 3; the output end of the isolating switch 5 and the output end of the circuit breaker 8 are connected to a section of the DC busbar 6, And the first section of DC bus 6 is connected to the second section of DC bus 10 through MMC rectifier 7 .

As a technical optimization scheme of the present invention, the first AC section 2 and the second AC section 3 are connected in series to the MMC rectifier 7 .

As a technical optimization scheme of the utility model, the section of DC bus 6 is connected to the controller 11 , the protector 12 and the distribution screens 13 of each level through the circuit breaker 8 respectively.

As a technical optimization scheme of the present invention, the power distribution screens 13 of each level include one of a feed screen, a main charging screen, a backup charging screen, and a battery screen.

When the utility model is in use, the MMC type rectifier 7 is used to convert the AC power supply into a DC power supply, support the DC bus voltage, and supply power for the station/factory DC load. The battery 1 is connected to the DC bus through the fuse 4 and the isolation switch 5. When the AC power fails, the battery 1 supports the voltage of the DC bus; the MMC inverter 9 is connected to the DC bus, when the AC power fails, the battery 1 provides DC power, and the MMC inverter 9 converts the DC power into AC The power supply provides uninterrupted power supply to the key station/factory AC load, and the circuit breaker 8 is used to isolate the faulty area according to the protection action command when the station/factory DC system fails. The 400V AC power supply of the station/factory is provided by two sections of AC busbars, and the two sections of AC busbars supply power to the MMC rectifier 7 at the same time, and the MMC type rectifier 7 converts the AC power supply into a DC power supply, supports the DC busbar voltage, and supplies power for the DC load of the station/factory . The storage battery 1 is connected to the DC bus through the fuse 4 and the isolation switch 5. When the 400V AC power supply of the station/factory is normal, the MMC rectifier 7 will float charge the battery 1 through the DC bus; when the 400V AC power supply of the station/factory fails, the battery 1 Support the voltage of the DC bus. The MMC inverter 9 is connected to the DC bus. When the 400V AC power supply of the station/factory is normal, the MMC inverter 9 is used as the backup power supply for the key station/factory AC load; when the 400V AC power supply of the station/factory fails, the battery 1 To provide DC power, the MMC type inverter 9 converts the DC power into AC power, and provides uninterrupted power supply to the AC loads used in key stations/plants. The fuse 4 is used to quickly isolate the battery 1 from the DC bus when an internal short circuit fault occurs in the battery 1 . The isolating switch 5 acts as a visual disconnection node. Electric screens 13 of each level (such as feed screen, main charging screen, backup charging screen, battery screen), protection circuit and control circuit are connected to the DC bus through the circuit breaker 8, and the circuit breaker 8 is used for the DC system in the station/factory When a fault occurs, isolate the faulty area according to the protection action instruction.

It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from all points of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, so it is intended to fall within the scope of the claims All changes within the meaning and range of equivalents of the required elements are included in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (4)

1. A DC system based on MMC for stations and factories, characterized in that: it comprises a rectification part and an inverter part, wherein the rectification part comprises a storage battery (1), an MMC type rectifier (7), a fuse (4) and An isolating switch (5), the output end of the storage battery (1) is connected in series with the input end of the fuse (4), and the output end of the fuse (4) is connected in series with the input end of the isolating switch (5); The inverter part includes an MMC type inverter (9) and a circuit breaker (8), and the MMC type rectifier (7) is connected through two sections of AC busbars, the AC busbars are the first section of AC (2) and the second section of AC (3 ); the output end of the isolating switch (5) and the output end of the circuit breaker (8) are connected to one section of the DC bus (6), and the section of the DC bus (6) is connected to the second section through the MMC type rectifier (7) on the DC bus (10). 2. The MMC-based DC system for station factory according to claim 1, characterized in that: the first AC stage (2) and the second AC stage (3) are connected in series to the MMC type rectifier (7). 3. A kind of MMC-based station plant DC system according to claim 1, characterized in that: said section of DC busbar (6) is connected to controller (11), protector (12) through circuit breaker (8) respectively ) and telescreens (13) for each grade. 4. A kind of DC system based on MMC according to claim 3, characterized in that: said electric screens (13) of each grade include feed screens, main charging screens, backup charging screens, and battery screens. one of the