Battery String Bypass Control for Redundant Fault Isolation
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Solution Overview
Problem
Energy storage systems with series-connected units face reliability issues due to the risk of whole-string failure when a fault occurs in both an energy storage unit and its corresponding controller or communication unit, leading to potential de-energization and failure.
Innovation Solution
The implementation of a series connection of energy storage units with multiple bypass circuits and control modules, where each control module can control its corresponding bypass circuit and at least one other, allowing for selective bypassing of faulty units even if one control module fails, thereby maintaining system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a series connection of energy storage units is used to achieve high voltage and power ratings, then the energy storage system can provide relatively high voltage and power, but the operational reliability decreases because failure in a single unit or its controller may result in failure of the whole string
Solution Approach 1:
The system divides the control function into multiple independent control modules, where each control module can control its own bypass circuit and at least one other bypass circuit. This segmentation ensures that a failure in one control module does not prevent bypassing of faulty energy storage units, as other control modules can take over the bypass function.
Solution Approach 2:
The patent implements redundant control capabilities beforehand by configuring each control module to control multiple bypass circuits. This preliminary arrangement ensures that if one control module fails, the system already has backup control paths in place, preventing whole-string failure and maintaining operational reliability.
2Ease of repair
If each energy storage unit has its own controller and bypass circuit for selective isolation, then faulty units can be isolated to keep remaining units operational, but if the controller or communication unit of a faulty unit also fails, the whole string may still fail
Solution Approach 1:
Each control module is designed with multi-functionality to control its corresponding bypass circuit and at least one other bypass circuit. This universal control capability ensures that bypass functions are not dependent on a single control module, and failure of one controller does not prevent fault isolation, as other control modules can perform the bypass operation.
3Ease of operation
If the protection circuit operation is controlled by the corresponding controller of each energy storage unit, then selective bypassing can be achieved, but the risk of whole-string failure increases when both the energy storage unit and its controller experience simultaneous faults
Solution Approach 1:
The patent implements local quality by distributing control functions across multiple control modules with overlapping capabilities. Each control module has the quality to control multiple bypass circuits, creating local redundancy that prevents single-point failures from propagating to the entire string, thus reducing the harmful effect of simultaneous faults.
Data Source
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AI summary
An arrangement (10) is disclosed, comprising a series connection of a plurality of energy storage units (1), a plurality of bypass circuits (2), each bypass circuit (2) being configured to bypass a respective one of the energy storage units (1) in the series connection, and a plurality of control modules (6, 7), wherein each control module (6, 7) corresponds to a respective one of the bypass circuits (2). Each control module (6, 7) is configured to control operation of the corresponding bypass circuit (2) and at least one other bypass circuit (2) of the plurality of bypass circuits (2) to selectively bypass the corresponding energy storage units (1) in the series connection in such a way that operation of each bypass circuit (2) of the plurality of bypass circuits (2) to selectively bypass the corresponding energy storage unit (1) in the series connection is controllable by means of at least two of the control modules (6, 7). A related method is also disclosed.