Power storage system having a plurality of power storage blocks interconnected in parallel and control device

1. A power storage system comprising:

a plurality of power storage blocks connected in parallel;

a power converter converting direct current (DC) power discharged from the plurality of the power storage blocks into alternating current (AC) power to output the AC power to a power system or a load and converting AC power sent from the power system into DC power to charge the plurality of the power storage blocks;

a plurality of switches interposed between the plurality of respective power storage blocks and the power converter; and

a management device calculating a state of power (SOP) of a whole of the plurality of power storage blocks based on an SOP of each of the plurality of the power storage blocks to specify the calculated SOP of the whole for an upper limit level of power or current for at least one of charging and discharging controlled by the power converter,

wherein when at least one of the plurality of the switches is turned off to disconnect at least one of the plurality of power storage blocks, the management device calculates an SOP of a whole of the remaining power storage blocks based on a deviation in current between each of the remaining power storage blocks to determine an upper limit level of power or current flowing into the power converter.

2. The power storage system according to claim 1 , wherein the management device calculates the SOP of the whole of the remaining power storage blocks by dividing a total of values of currents flowing through the respective remaining power storage blocks by a largest value of the values of the currents to determine a quotient and multiplying a minimum value of values of the SOP of each of the remaining power storage blocks by the quotient.

3. The power storage system according to claim 1 , wherein the management device decreases the upper limit level of power or current flowing into the power converter to a predetermined power value or a current value and subsequently turns off at least one of the switches connected to the at least one of the power storage blocks to disconnect at least one of the plurality of power storage blocks.

4. The power storage system according to claim 3 , wherein

the predetermined power value is a variable value, and

the management device determines the predetermined power value by reference to at least one of an operation mode in which the power storage system is put, a record of a number of actions of the switch, and a setting value set manually.

5. The power storage system according to claim 1 , wherein the management device calculates, without one of the power storage blocks with a largest current among currents flowing through the plurality of respective power storage blocks, an SOP of a whole of the remaining power storage blocks, and turns off the switch connected to the power storage block with the largest current on condition that the calculated SOP is greater than the SOP of the whole of the plurality of power storage blocks at present.

6. A power storage system comprising:

a plurality of power storage blocks connected in parallel;

a power converter converting direct current (DC) power discharged from the plurality of power storage blocks into alternating current (AC) power to output the AC power to a power system or a load and converting AC power sent from the power system into DC power to charge the plurality of power storage blocks;

a plurality of switches interposed between the plurality of respective power storage blocks and the power converter; and

a management device configured to decrease an upper limit level of power or current for at least one of charging and discharging controlled by the power converter to a predetermined power value or a current value and subsequently turn off at least one of the switches connected to at least one of the power storage blocks in response to occurrence of an event that requires the at least one of the power storage blocks to be disconnected.

7. A management device connected to a power storage system that includes:

a plurality of power storage blocks connected in parallel;

a power converter converting direct current (DC) power discharged from the plurality of the power storage blocks into alternating current (AC) power to output the AC power to a power system or a load and converting AC power sent from the power system into DC power to charge the plurality of the power storage blocks; and

a plurality of switches interposed between the plurality of respective power storage blocks and the power converter,

wherein the management device calculates a state of power (SOP) of a whole of the plurality of power storage blocks based on an SOP of each of the plurality of power storage blocks to specify the calculated SOP of the whole for an upper limit level of power or current for at least one of charging and discharging controlled by the power converter, and

when at least one of the plurality of switches is turned off to disconnect at least one of the plurality of power storage blocks, the management device calculates an SOP of a whole of the remaining power storage blocks based on a deviation in current between each of the remaining power storage blocks to determine an upper limit level of power or current flowing into the power converter.