TECHNICAL FIELD

The present invention relates to a power storage system including plurality of power storage modules, and a management device.

BACKGROUND ART

Recently, a power storage system has been, widespread, and is used for a peak shift, backup, a frequency regulation (FR), and the like. A huge power storage system is constructed by, for example, connecting in parallel a plurality of power storage racks each including by connecting in series a plurality of power storage modules.

When a temperature difference exists among the power storage racks connected in parallel, a variation occurs in internal resistances of the power storage modules due to the temperature difference, causing a resistance difference among the plurality of power storage racks. For example, when the power storage system is installed indoors, a temperature difference occurs between a power storage rack near an air conditioner and a power storage rack away from the air conditioner. The internal resistance of the power storage module becomes larger as its temperature becomes lower.

CITATION LIST

Patent Literature

PTL 1: Unexamined Japanese Patent Publication No. 2014-203536

SUMMARY OF THE INVENTION

When a resistance difference occurs among the plurality of, power storage racks, a occurs in charge and discharge current among the plurality of power storage racks. When a variation in current occurs, it becomes difficult to secure the maximum power supply of the power storage system. Specifically, current flowing in a power storage rack whose temperature is low and whose resistance is large becomes small. In contrast, although a power storage rack whose temperature is high and whose resistance is small tries to increase current, a breakdown voltage or an allowable current is set in each element composing the power storage rack, making it impossible to flow current exceeding the allowable current. Therefore, when a resistance difference occurs among the plurality of power storage racks connected in parallel, current flowing in the whole plurality of power storage racks connected in parallel is reduced, resulting in lowering of power supply capacity.

The present invention has been conceived in light of such circumstances, and an object thereof is to provide a technique for reducing a variation of currents among a plurality of power storage module groups connected in parallel.

In order to solve the above problem, a power storage system, of an aspect of the present invention includes:

a power storage unit in which a plurality of power storage module groups are connected in parallel, each of the plurality of power storage module groups including a plurality of power storage modules connected in series or in series and parallel;

a plurality of temperature adjustment units installed each of the power storage module groups constituting the power storage unit and configured to cool or heat the power storage module groups; and

a management unit configured to control each of the plurality of temperature adjustment units corresponding to each of the power storage module groups to make resistances of the plurality of power storage module groups come close.

Any desired combinations of the above-described components and converted expressions of the present invention in methods, devices, systems, and other similar entities are still effective as aspects of the present invention.

Advantageous Effect of Invention

The present invention makes it possible to reduce a variation of currents in the respective plurality of power storage modules connected in parallel.

