Storage battery control device, power storage system, and storage battery control method

A power storage system comprising:

• a plurality of storage batteries connected in series;
• a bypass circuit configured to bypass each of the storage batteries;
• and
• a storage battery control device configured to control the bypass circuit,
• wherein the storage battery control device is configured to execute:
• a first process of causing each of the plurality of storage batteries to discharge while switching the storage batteries bypassed by the bypass circuit so as to reduce a difference between remaining discharge a mounts until discharge completion of the plurality of storage batteries, and
• a second process of completing the discharge of the plurality of storage batteries after the first process,
• the first process is executed until an open circuit voltage (OCV) or a state of charge (SOC) of each of the storage batteries decreases to be equal to or smaller than a threshold value of the OCV or the SOC set for each of the storage batteries,
• the first process is executed according to a predetermined discharge bypass schedule so that available output power of the storage battery caused to discharge does not fall below minimum necessary power of a power supply destination,
• the predetermined discharge bypass schedule is set in time series such that a combination of two or more of the plurality of storage batteries to be discharged and one or more of the storage batteries to be bypassed is set so as to reduce a difference between remaining discharge amounts until discharge completion of the plurality of storage batteries, and
• the predetermined discharged bypass schedule includes a plurality of successive periods along a timeline, and is set such that the combination subsequently switches in each of the plurality of periods.

A storage battery control method executed using a storage battery control device configured to control a power storage system including a plurality of storage batteries connected in series and a bypass circuit configured to bypass each of the storage batteries, the storage battery control method comprising

• executing, by the storage battery control device,
• a first procedure of causing each of the plurality of storage batteries to discharge while switching the storage batteries caused to be bypassed by the bypass circuit so as to reduce a difference between remaining discharge amounts until discharge completion of the plurality of storage batteries;
• and
• a second procedure of completing the discharge of the plurality of storage batteries after the first procedure,
• wherein the first procedure is executed by the storage battery control device until an open circuit voltage (OCV) or a state of charge (OCV) of each of the storage batteries decreases to be equal to or smaller than a threshold value of the open circuit voltage or the SOC set for each of the storage batteries,
• the first procedure is executed by the storage battery control device according to a predetermined discharge bypass schedule so that available output power of the storage battery caused to discharge does not fall below minimum necessary power of a power supply destination,
• the predetermined discharge bypass schedule is set in time series such that a combination of two or more of the plurality of storage batteries to be discharged and one or more of the storage batteries to be bypassed is set so as to reduce a difference between remaining discharge amounts until discharge completion of the plurality of storage batteries, and
• the predetermined discharged bypass schedule includes a plurality of successive periods along a timeline, and is set such that the combination subsequently switches in each of the plurality of periods.