Battery String Parameter Control for Higher Allowable System Current
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Solution Overview
Problem
Energy storage systems face limitations in allowable system current due to variations in internal resistance among battery strings, leading to reduced power production capacity and potential inability to meet energy demands, as controllers derate the system current to prevent individual battery strings from exceeding their ratings.
Innovation Solution
A method and system where a controller determines the limiting energy storage device and adjusts operational parameters such as resistance, temperature, and state-of-charge to increase the allowable system current, allowing for higher power production while maintaining safety constraints, by disconnecting, cooling, or repositioning the limiting device within the energy storage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller derates the allowable system current to prevent individual battery strings from exceeding their current ratings, then the reliability of individual battery strings is improved, but the power production capacity of the energy storage system deteriorates
Solution Approach 1:
The controller dynamically adjusts operational parameters (temperature, state-of-charge) of individual battery strings to modify their resistance characteristics. By changing these parameters, the system can redistribute current flow among parallel battery strings, allowing the system to operate at higher total current levels while keeping individual string currents within safe limits.
Solution Approach 2:
The system transitions from a static derated current limit to a dynamic current distribution strategy. The controller continuously monitors and adjusts the operational state of each battery string in real-time, enabling the system to adaptively maximize power output while maintaining reliability through active parameter management rather than fixed current reduction.
2Reliability
If the controller reduces the allowable system current to account for current discrepancies among parallel-connected energy storage devices, then the safety of individual energy storage devices is improved, but the total power delivery capability of the system deteriorates
Solution Approach 1:
The controller modifies operational parameters such as temperature and state-of-charge of individual battery strings to alter their electrical resistance. This enables current redistribution across parallel strings, allowing the system to deliver higher total power while maintaining individual device safety through dynamic parameter adjustment rather than uniform current reduction.
Solution Approach 2:
The system applies different operational conditions to different battery strings based on their individual characteristics and current states. Each battery string can operate at different temperatures and states-of-charge, creating localized optimal conditions that maximize overall system power delivery while maintaining safety margins for each individual device.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the allowable system current and usable capacity of energy storage systems, optimizing power output while ensuring operational safety and extending the system's operational lifetime.
Implementation Method 1
determining a second allowable system current based at least in part on disconnecting the limiting energy storage device from the energy storage system, determining a third allowable system current based at least in part on decreasing a temperature of the limiting energy storage device
Data Source
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AI summary
The present disclosure is directed to a system and method for controlling an energy storage system. The energy storage system includes a plurality of parallel-connected energy storage devices. The method includes determining, by one or more controllers, a limiting energy storage device based at least in part on a current rating for the limiting energy storage device. The method includes determining, by the one or more controllers, an adjusted allowable system current based at least in part on modifying one or more operational parameters of the limiting energy storage device. The method includes determining, by the one or more controllers, a modified operational parameter of the limiting energy storage device to increase the allowable system current of the energy storage system. The method includes controlling the limiting energy storage device based at least in part on the modified operational parameter.