Battery Pack Grouping for ESS Charging and Discharging Control
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Solution Overview
Problem
The frequent switching between charging and discharging operations in battery packs within energy storage systems reduces the service life and causes damage, necessitating a control method to minimize these transitions.
Innovation Solution
Designating battery packs into charging and discharging groups managed by separate battery management systems and controlling them to perform charging or discharging operations only when necessary, with switching occurring when state of charge thresholds are exceeded or reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all battery packs are charged during charging mode and discharged during discharging mode to maintain balanced SoC, then the BMS can maintain uniform state of charge across battery packs, but the frequency of switching between charging and discharging operations increases, reducing battery pack service life
Solution Approach 1:
The patent divides battery packs into two distinct groups: a charging group and a discharging group. This segmentation allows different operational modes to be applied to different subsets of battery packs simultaneously, resolving the contradiction by enabling SoC balance maintenance without requiring all packs to undergo frequent charging/discharging cycles. The BMS manages these groups independently, with the charging group being charged during charging mode and the discharging group being discharged during discharging mode.
Solution Approach 2:
The patent implements dynamic group switching based on real-time SoC monitoring. When battery packs reach predetermined SoC thresholds, they are dynamically transferred between charging and discharging groups. This dynamic adjustment allows the system to maintain optimal SoC balance while minimizing the frequency of charging/discharging operations for individual battery packs, thereby extending their service life.
2Productivity
If frequent switching between charging and discharging operations is performed, then the BMS can respond quickly to load changes and renewable energy availability, but the service life of battery packs is reduced and damage occurs
Solution Approach 1:
By segmenting battery packs into charging and discharging groups, the system can respond to load changes and renewable energy availability through group-level operations rather than requiring individual pack switching. This maintains high productivity at the system level while reducing operational stress on individual battery packs.
Solution Approach 2:
The system performs preliminary charging of the charging group and preliminary discharging of the discharging group in advance, so when load changes or renewable energy availability changes occur, the system can respond quickly using the pre-prepared groups without needing to switch individual battery packs frequently.
Data Source
AI summary
A method of controlling charging/discharging of battery packs in an energy storage system (ESS) includes designating first battery packs, managed by a first battery management system (BMS), as a charging group and designating second battery packs, managed by a second BMS, as a discharging group. The method further includes controlling the first BMS to permit only the first battery packs designated as the charging group to undergo a charging operation when the ESS is operated in a charging mode, and controlling the second BMS to permit only the second battery packs designated as the discharging group to undergo a discharging operation when the ESS is operated in a discharging mode.