Power conversion system

Patent metadata

Field	Value
Publication number	US-12322969-B2
Application number	US-202018040062-A
Country	US
Kind code	B2
Filing date	Aug 21, 2020
Priority date	Aug 21, 2020
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

A power conversion system includes a plurality of power conversion devices connected to a plurality of AC systems, respectively. The power conversion devices are further connected to a common DC circuit. The power conversion system further includes a start-up device to start up each power conversion device. The start-up device selects an AC system that satisfies a defined condition relating to power supply capability from among the plurality of AC systems based on system information of the plurality of AC systems and starts up a power conversion device connected to the selected AC system.

First claim

The invention claimed is:

1. A power conversion system comprising:
a plurality of power conversion devices connected to a plurality of AC systems, respectively, the power conversion devices being further connected to a common DC circuit; and
a start-up device to start up each of the power conversion devices, wherein
the start-up device
selects an AC system that satisfies a defined condition relating to power supply capability from among the plurality of AC systems based on system information of the plurality of AC systems, and
starts up a power conversion device connected to the selected AC system,

the system information of the AC system includes an RMS voltage of the AC system, a voltage difference between the RMS voltage of the AC system and a reference RMS voltage, and a short-circuit capacity of the AC system, and
the start-up device
sets the defined condition to a first condition relating to the RMS voltage when the short-circuit capacity of each of the plurality of AC systems is equal to or higher than a defined capacity, and
sets the defined condition to a second condition relating to the voltage difference when at least one of a plurality of short-circuit capacities of the plurality of AC systems is lower than the defined capacity.

2. The power conversion system according to claim 1 , wherein
when the defined condition is set to the first condition, the start-up device selects, as the AC system that satisfies the first condition, an AC system having a maximum RMS voltage among the plurality of AC systems or an AC system having the RMS voltage equal to or higher than a first threshold value among the plurality of AC systems.

3. The power conversion system according to claim 2 , wherein
when the defined condition is set to the second condition, the start-up device selects, as the AC system that satisfies the second condition, an AC system having a minimum voltage difference among the plurality of AC systems or an AC system having the voltage difference smaller than a second threshold value among the plurality of AC systems.

4. The power conversion system according to claim 2 , wherein
the power conversion device includes a modular multilevel conversion power converter.

5. The power conversion system according to claim 2 , wherein
the power conversion device includes a modular multilevel conversion power converter.

6. The power conversion system according to claim 1 , wherein
when the defined condition is set to the second condition, the start-up device selects, as the AC system that satisfies the second condition, an AC system having a minimum voltage difference among the plurality of AC systems or an AC system having the voltage difference smaller than a second threshold value among the plurality of AC systems.

7. The power conversion system according to claim 1 , wherein
when the defined condition is set to the first condition,
the start-up device
calculates, for each of the plurality of AC systems, a first ratio of the RMS voltage of the AC system to the reference RMS voltage of the AC system, and
selects, as the AC system that satisfies the first condition, an AC system having a maximum first ratio among the plurality of AC systems or an AC system having the first ratio equal to or higher than a third threshold value among the plurality of AC systems.

8. The power conversion system according to claim 7 , wherein
when the defined condition is set to the second condition,
the start-up device
calculates, for each of the plurality of AC systems, a second ratio of the voltage difference in the AC system to the reference RMS voltage of the AC system, and
selects, as the AC system that satisfies the second condition, an AC system having a minimum second ratio among the plurality of AC systems or an AC system having the second ratio lower than a fourth threshold value among the plurality of AC systems.

9. The power conversion system according to claim 7 , wherein
the power conversion device includes a modular multilevel conversion power converter.

10. The power conversion system according to claim 1 , wherein
when the defined condition is set to the second condition,
the start-up device
calculates, for each of the plurality of AC systems, a second ratio of the voltage difference in the AC system to the reference RMS voltage of the AC system, and
selects, as the AC system that satisfies the second condition, an AC system having a minimum second ratio among the plurality of AC systems or an AC system having the second ratio lower than a fourth threshold value among the plurality of AC systems.

11. The power conversion system according to claim 8 , wherein
the power conversion device includes a modular multilevel conversion power converter.

12. The power conversion system according to claim 1 , wherein
the power conversion device includes a modular multilevel conversion power converter.

13. A power conversion system comprising:
a plurality of power conversion devices connected to a plurality of AC systems, respectively, the power conversion devices being further connected to a common DC circuit; and
a start-up device to start up each of the power conversion devices, wherein
the start-up device
selects an AC system that satisfies a defined condition relating to power supply capability from among the plurality of AC systems based on system information of the plurality of AC systems, and
starts up a power conversion device connected to the selected AC system,

each of pieces of the system information is a short-circuit capacity of each of the AC systems, and
the start-up device selects, as the AC system that satisfies the defined condition, an AC system having a maximum short-circuit capacity among the plurality of AC systems or an AC system having the short-circuit capacity equal to or higher than a threshold value among the plurality of AC systems.

14. The power conversion system according to claim 13 , wherein
the power conversion device includes a modular multilevel conversion power converter.

15. A power conversion system comprising:
a plurality of power conversion devices connected to a plurality of AC systems, respectively, the power conversion devices being further connected to a common DC circuit; and
a start-up device to start up each of the power conversion devices, wherein
the start-up device
selects an AC system that satisfies a defined condition relating to power supply capability from among the plurality of AC systems based on system information of the plurality of AC systems, and
starts up a power conversion device connected to the selected AC system,

each of pieces of the system information is a system capacity of each of the AC systems,
the system capacity of the AC system is a summed capacity of one or more generators connected to the AC system, and
the start-up device selects, as the AC system that satisfies the defined condition, an AC system having a maximum system capacity among the plurality of AC systems or an AC system having the system capacity equal to or higher than a threshold value among the plurality of AC systems.

16. The power conversion system according to claim 15 , wherein
the power conversion device includes a modular multilevel conversion power converter.

Assignees

• Mitsubishi Electric Corp

Inventors

• Fujiwara Shuhei
• Kono Yoshiyuki
• Uda Ryosuke
• KAJIYAMA Takuya
• Fujii Toshiyuki

Classifications

• H02M7/4835

  comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage · CPC title

• Y02E60/60

  Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] · CPC title

• H02J3/36

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title

• H02M1/36

  Means for starting or stopping converters · CPC title

• H02J3/06 Primary

  Controlling the transfer of power between connected networks; Controlling load sharing between connected networks · CPC title