US 12,155,216 B2
DC grid system, control device, and control method
Ryo Wakabayashi, Tokyo (JP); Toru Kouno, Tokyo (JP); Satoru Akiyama, Tokyo (JP); Emha Bayu Miftahullatif, Tokyo (JP); and Katsutoshi Kondo, Tokyo (JP)
Assigned to HITACHI, LTD., Tokyo (JP)
Appl. No. 18/031,361
Filed by HITACHI, LTD., Tokyo (JP)
PCT Filed Oct. 6, 2021, PCT No. PCT/JP2021/037043
§ 371(c)(1), (2) Date Apr. 12, 2023,
PCT Pub. No. WO2022/097413, PCT Pub. Date May 12, 2022.
Claims priority of application No. 2020-185236 (JP), filed on Nov. 5, 2020.
Prior Publication US 2023/0378759 A1, Nov. 23, 2023
Int. Cl. H02J 3/38 (2006.01); H02J 3/32 (2006.01)
CPC H02J 3/381 (2013.01) [H02J 3/32 (2013.01); H02J 2300/24 (2020.01)] 9 Claims
OG exemplary drawing
 
1. A DC grid system in which a storage battery is connected to a DC bus, the DC grid system comprising:
a first converter configured to convert an alternating current voltage input from an alternating current power system into a first direct current voltage;
a second converter configured to convert a second direct current voltage input from the storage battery into a third direct current voltage;
a DC bus that connects the first converter and the second converter; and
a control unit configured to provide a command value to the first converter and to the second converter, wherein
the control unit calculates a first voltage command value of the DC bus in the first converter and a second voltage command value of the DC bus in the second converter based on the second direct current voltage, a target voltage of the storage battery, and a voltage of the DC bus, and a voltage ratio between a voltage of the storage battery and the voltage of the DC bus, and
the control unit controls the voltage of the DC bus in conjunction with the target voltage by providing the first voltage command value as the command value for the first converter and providing the second voltage command value as the command value for the second converter.