Battery Rack DC/DC Control for Adding New ESS Capacity
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Solution Overview
Problem
Existing energy storage systems face inefficiencies when new battery racks are added due to performance differences with existing racks, leading to unnecessary balancing and suboptimal utilization of new racks, affecting charge/discharge efficiency and overall Round Trip Efficiency (RTE).
Innovation Solution
A control apparatus is implemented to manage a system with central and parallel DC/DC converters, monitoring and controlling the output of both existing and new battery racks, ensuring simultaneous power delivery and calculating optimal power command values based on rack-specific information such as SOH, SOC, and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If new battery racks are added to existing battery racks to supplement performance, then the overall capacity and performance of the energy storage system is improved, but performance differences between new and existing racks cause unnecessary repeated rack balancing operations
Solution Approach 1:
The patent segments the battery system into distinct groups: existing battery racks and newly added battery racks. Each group is managed by separate DC/DC converters that can operate independently. This segmentation allows the new racks to be controlled separately from existing racks, preventing the performance differences between them from causing unnecessary balancing operations while still contributing to overall system capacity.
2Reliability
If new battery racks are added to existing battery racks, then performance compensation is achieved, but the new battery racks cannot fully utilize their maximum performance due to following the performance of existing racks
Solution Approach 1:
The patent implements dynamic control where the DC/DC converter for newly added battery racks can adjust its operation mode based on system conditions. The converter can operate in different modes (e.g., constant current, constant voltage, power control) and can independently manage the charge/discharge operations of new racks, allowing them to fully utilize their performance capabilities rather than being constrained by the performance characteristics of existing racks.
3Adaptability or versatility
If various types of connection structures are used for adding new battery racks, then system flexibility is improved, but charge/discharge efficiency and overall RTE are reduced
Solution Approach 1:
The patent introduces a DC/DC converter as an intermediary device between the newly added battery racks and the rest of the energy storage system. This intermediary enables flexible connection structures (series, parallel, or hybrid configurations) while maintaining optimal charge/discharge efficiency. The DC/DC converter acts as a buffer that isolates the new racks from the existing system, allowing connection flexibility without energy losses that would otherwise result from direct connections.
Data Source
AI summary
Discussed is an energy storage system that may include a plurality of first battery racks; a central DC/DC converter connected to the plurality of first battery racks and configured to perform power conversion; a plurality of second battery racks; and a plurality of DC/DC converters connected to the plurality of second battery racks respectively and configured to perform power conversion. Here, the central DC/DC converter and the plurality of DC/DC converters are connected in parallel to a DC bus connected to at least one of a power conversion device (PCS) and a power generation device.