Parallel Power Storage Block SOP Recalculation
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Solution Overview
Problem
Power storage systems connected in parallel often disconnect when an abnormality occurs in one rack, leading to unstable operation due to current deviations between remaining racks, causing power limits to be exceeded and resulting in system shutdown.
Innovation Solution
A power storage system with a power converter and management device that calculates the state of power for each block, adjusts the upper limit of power or current, and disconnects affected blocks to maintain stability by recalculating the system state based on current deviations between remaining blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an abnormal power storage rack is disconnected and the upper limit of electric power is decreased according to the number of remaining racks, then the system can continue operation, but large current deviations between remaining racks cause power limits to be exceeded and lead to system shutdown
Solution Approach 1:
The management device continuously monitors the current flowing through each power storage rack and uses this feedback to dynamically adjust the upper limit of electric power for each rack. When current deviation is detected, the system automatically recalculates and redistributes power limits to maintain balance, preventing any single rack from exceeding its power limit and causing system shutdown.
Solution Approach 2:
The upper limit of electric power for each power storage rack is not fixed but dynamically adjusted based on real-time operating conditions. The management device continuously recalculates the SOP of remaining racks and updates power limits accordingly, allowing the system to adapt to changing conditions after rack disconnection and maintain stable operation.
2Reliability
If the upper limit of electric power is decreased to accommodate fewer racks, then operation continues, but this reduction in power limit reduces the overall power output capability of the system
Solution Approach 1:
The system changes the parameter of power distribution by redistributing the total power capacity among remaining racks based on their individual capabilities and current operating conditions. Instead of uniformly decreasing power limits, the management device calculates optimized power limits for each rack that maximize overall system output while ensuring no single rack is overloaded, thus maintaining both reliability and power output.
3Power
If power limits are not adjusted after rack disconnection, then maximum power output is maintained, but individual racks may exceed their safe operating limits causing sequential disconnections and system shutdown
Solution Approach 1:
The management device performs preliminary calculation of the State of Power (SOP) for each remaining rack before allowing operation to continue. By pre-calculating safe power limits based on the number and condition of remaining racks, the system prevents future overloads and sequential disconnections, ensuring stable operation while maximizing power output within safe boundaries.
Data Source
AI summary
In a power storage system, a management device calculates a state of power (SOP) of a whole of a plurality of power storage blocks connected in parallel 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 a power converter. When at least one of a plurality of switches is turned off to disconnect at least one (30) 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.