SOC Range Switching for Battery Storage Life Retention
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Solution Overview
Problem
In power storage systems, repeated charging and discharging within a narrow SOC range accelerates the deterioration of power storage facilities and batteries, particularly when using lithium iron phosphate as the positive electrode active material.
Innovation Solution
The method involves grouping power storage facilities into multiple groups and setting multiple SOC ranges shifted from each other as operational options. Each group is operated within a selected SOC range, and the SOC range is sequentially switched among the options to prevent continuous operation within a single range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power storage facilities are charged and discharged repeatedly in a narrow SOC range (50% or less width), then the power storage system can maintain charge and discharge reserves at any timing, but the deterioration of power storage facilities and batteries is accelerated
Solution Approach 1:
The power storage facilities are divided into multiple groups, and the SOC range is segmented into multiple sub-ranges (first SOC range and second SOC range). Each group operates in different sub-ranges, which distributes the stress from repeated charging/discharging across different SOC intervals, thereby reducing deterioration while maintaining system reserves.
Solution Approach 2:
The operation SOC range is switched between the first SOC range and the second SOC range in a periodic manner. This periodic switching allows the power storage facilities to alternate between different SOC intervals, preventing continuous operation in a single narrow range and reducing cumulative deterioration effects while ensuring charge and discharge reserves are maintained.
2Reliability
If the operation SOC range is fixed in a narrow range, then the power storage system can secure charge and discharge reserves at any timing, but the capacity retention ratio decreases over time due to accelerated deterioration
Solution Approach 1:
The operation SOC range is made dynamic by switching between the first SOC range and the second SOC range. This dynamic adjustment allows the system to adaptively change operating intervals, preventing the fixed narrow range operation that leads to capacity degradation while maintaining the necessary charge and discharge reserves.
Solution Approach 2:
The SOC range parameters (lower limit and upper limit values) are changed by switching between different predefined ranges. This parameter change strategy allows the system to operate in different SOC intervals periodically, reducing the cumulative effect of narrow-range operation on capacity retention while ensuring system reserves are secured.
Data Source
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AI summary
In an approach, in an operation method of a power storage system (1), a plurality of SOC ranges (X) shifted from each other are set, and one of the SOC ranges (X) to be an option is selected as an operation SOC range for each of a plurality of groups (Y) so as to be in a state where the SOC ranges (X) selected are different between the groups (Y). In the operation method, a power storage facility (3) belonging to each of the groups (Y) is operated in the SOC range (X) selected as the operation SOC range, and the SOC range (X) to be selected as the operation SOC range is sequentially switched between the plurality of SOC ranges (X) for each of the groups (Y) so as to be in a state in where the SOC ranges (X) selected are different between the groups (Y).