Battery String Bypass Sequencing for Stable Charge-Discharge Power
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Solution Overview
Problem
In electric power storage systems with multiple storage battery strings connected in parallel and equipped with bypass circuits, maintaining target charging and discharging power or current becomes challenging when bypass control is executed, due to sudden changes in power or current.
Innovation Solution
A storage battery control device that allocates the instruction value of charging or discharging power or current from a storage battery string to be controlled by the bypass circuit to other storage battery strings not under bypass control, and stops the power converter of the storage battery string to be controlled by the bypass circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass control is executed for a storage battery string, then the storage battery can be protected from overcharging and overdischarging, but the charging and discharging power of the entire electric power storage system suddenly changes
Solution Approach 1:
The control device performs preliminary action by allocating the charging/discharging power instruction value to other storage battery strings before executing bypass control. This preemptive reallocation ensures that when the bypass circuit activates and the original string's power contribution changes suddenly, the other strings are already prepared to compensate, preventing system power instability
Solution Approach 2:
Before the bypass control is executed, the control device stops the power converter of the storage battery string that will undergo bypass control and reallocates its instruction value to other strings. This preliminary action sequence ensures that the reallocation is completed before the sudden power change occurs, maintaining system stability
2Stability of the object's composition
If the charging and discharging power instruction value is reallocated to other storage battery strings before bypass control, then the target charging and discharging power of the system is maintained, but the control complexity increases
Solution Approach 1:
The control device integrates multiple functions into a unified control mechanism: it monitors the states of all storage battery strings, manages power converter operations, executes bypass control, and reallocates power instruction values. This multi-functional approach consolidates what could be separate complex control systems into one coordinated device, managing complexity through integration rather than multiplication of independent control circuits
Data Source
AI summary
A storage battery control device allocates an instruction value of charging or discharging power or current of a plurality of storage battery strings, controls a bypass switch unit, and controls a power converter. The storage battery control device, before controlling the bypass switch unit, allocates the instruction value allocated to the storage battery string to be subjected to bypass control to one or more of the storage battery strings not to be subjected to bypass control, and stops the power converter of the storage battery string to be subjected to bypass control.